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- 1-Reciprocating Compressors for industrial refrigeration / Series Grasso 6PI2010/v007

Reciprocating Compressors for industrial refrigeration

Series Grasso 6

Product Information (PI)

pador9050

- 2- Reciprocating Compressors for industrial refrigeration / Series Grasso 6 PI2010/v007

Copyright

All Rights reserved. No part of this publication may be copied or published by means of printing, photocopying, microfilm or otherwise without prior written consent of Grasso.This restriction also applies to the corresponding drawings and diagrams.

Legal Notice

This publication has been written in good faith. However, Grasso cannot be held responsible, neither for any errors occurring in this publication nor for their consequences.


Table of Contents

Section Title Page

1 DESCRIPTION AND SELECTION OF COMPRESSOR 9

1.1 INTRODUCTION AND SCOPE 9

1.1.1 OUTLINE 9

1.1.2 TYPE DESIGNATION 9

1.1.3 APPLICATION 9

1.1.4 DRIVE SYSTEM 9

1.1.5 SELECTION COMPRESSOR AND ACCESSORIES 9

1.1.6 PRESSURE TESTS 9

1.1.7 ACCEPTANCE TEST 9

1.1.8 STANDARD SCOPE OF SUPPLY 9

1.1.9 OPTIONS 9

1.2 GENERAL DATA 11

1.2.1 TECHNICAL DATA 11

1.2.2 MAIN DIMENSIONS AND SPACE REQUIREMENTS 12

1.2.3 SHAFT END COMPRESSOR 13

1.2.4 SOUND RATING GENERAL 13

1.2.4.1 SOUND DATA 6 13

1.2.5 STARTING TORQUE 14

1.2.5.1 STARTING TORQUE NUMBERS GRASSO 6 15

1.2.6 FREE FORCES AND MOMENTS 15

1.2.6.1 DETAILS 15

1.2.7 POSITION OF CENTRE OF GRAVITY 16

1.2.7.1 COORDINATES POSITION OF CENTRE GRAVITY 16

1.2.8 TORSIONAL ELASTIC SUBSITUTE SYSTEMS OF CRANKSHAFTS 16

1.3 LIMITS OF OPERATION AND FIELDS OF APPLICATION 19

1.3.1 GENERAL LIMITS AND FIELDS OF OPERATION GRASSO 6 19

1.3.2 PRECISE FIELD OF APPLICATION 19

1.3.3 FIELDS OF APPLICATION 20

1.3.4 LIMITATIONS OF PART-LOAD OPERATION 21

1.4 LUBRICATING OILS (choice and recommendations) 23

1.4.1 OIL SELECTION TABLE 23

1.4.1.1 REMARKS 23

1.4.2 STRONGLY RECOMMENDED OIL TYPES 23

1.4.3 ACCEPTED NH3 AND HCFC OIL TYPES 24

1.4.4 ACCEPTED HFC OIL TYPES 24

1.5 DESIGN DETAILS OF COMPRESSOR 25

1.5.1 COMPRESSOR HOUSING 25

1.5.1.1 DIAGRAMS Grasso 6(W) 26

1.5.2 CYLINDERS AND MOVING PARTS 27

1.5.3 ROTARY SHAFT SEAL 27

1.5.3.1 DETAILS ROTARY SHAFT SEAL 27


1.5.4 SUCTION AND DISCHARGE VALVES 27

1.5.4.1 DETAILS SUCTION AND DISCHARGE VALVE ASSEMBLY 27

1.5.5 CAPACITY CONTROL SYSTEMS 28

1.5.5.1 GENERAL 28

1.5.5.2 DESCRIPTION OF CAPACITY CONTROL 28

1.5.5.3 OPERATION OF CAPACITY CONTROL 28

1.5.5.4 PARTIALLY UNLOADED STARTING 28

1.5.5.5 ALTERNATIVES OF CAPACITY CONTROL 29

1.5.5.6 DIAGRAM CAPACITY CONTROL 30

1.5.6 CYLINDER HEAD COVERS 30

1.5.7 WATER COOLED OIL COOLER 31

1.5.8 OVERFLOW SAFETY VALVE AND PRESSURE EQUALISING 31

1.5.8.1 DETAILS PRESSURE RELIEF VALVE 31

1.5.9 DIRECT DRIVE OIL PUMP 31

1.5.9.1 OIL LUBRICATION SYSTEM 33

1.5.9.2 OIL CHANNEL 33

1.5.10 MAIN CONNECTIONS AND SUCTION GAS STRAINER 33

1.5.10.1 DETAILS SUCTION GAS STRAINER 33

2 DESCRIPTION AND SELECTION OF ACCESSORIES 35

2.1 PART-LOAD POWER CONSUMPTION AND ALLOWED PART LOAD STEPS COMSEL 35

2.2 CYLINDER NUMBERING 35

2.3 CAPACITY CONTROL 36

2.4 CONTROLS, SAFETIES, GAUGES AND SWITCHES 37

2.4.1 CONTROLS SINGLE STAGE 37

2.4.2 “GSC OP” AND “GSC TP” CONTROL DEVICE 37

2.4.3 MECHANICAL SAFETY SWITCHES IN ADDITION TO MICRO-PROCESSOR-BASED CONTROL SYSTEMS 38

2.4.4 PRESSURE GAUGE AND SAFETY SWITCH PANEL 38

2.5 DIRECT AND V-BELT DRIVE 41

2.5.1 SELECTION OF DIRECT DRIVE 41

2.5.2 SELECTION OF V-BELT DRIVE 41

2.5.2.1 DETAILS V-BELT DRIVE 42

2.6 PACKAGED BASE FRAME 43

2.6.1 PACKAGED BASE FRAME 45

2.7 OIL SEPARATOR; OIL RETURN PROTECTION; OIL LEVEL FLOAT SWITCH; OIL EQUALISING AND OIL RETURN 47

2.7.1 (COMMON) OIL RETURN SYSTEMS 47

2.7.1.1 EXPLANATION OIL RETURN SCHEMATICS (Section 2.7.1.2 and Section 2.7.1.3) 47

2.7.1.2 SCHEMATIC OIL RETURN SYSTEM I 47

2.7.1.3 SCHEMATIC OIL RETURN SYSTEM II 48

2.7.2 OIL SEPARATORS 48

2.7.3 OIL RETURN PROTECTION 51

2.7.4 CRANKCASE OIL LEVEL SWITCH 52

2.7.4.1 DETAILS CRANKCASE OIL LEVEL FLOAT SWITCH 52

2.8 WATER COOLED CYLINDER HEADS AND COOLING WATER REQUIREMENTS 55

Section Title Page


2.9 CRANKCASE HEATER 55

2.9.1 DETAILS CRANKCASE HEATER 56

2.10 STOP VALVES, CHECK VALVES AND FLANGES SUCTION AND DISCHARGE CONNECTIONS 56

2.11 HAND-OPERATED OIL PUMP 56

Section Title Page


Preface documentations

Typographic signs:

Indicates a WARNING. READ IT CAREFULLY!

Indicates an IMPORTANT note or procedure to which you should pay special attention.

Indicates a HINT.

General

1 All documentation can be downloaded via grasso-global.com.

2 Grasso’s technical manuals includes “generic paragraphs”; this means that it can occur that not all data as described is relevant for the current compressor series as mentioned in this manual. (For instance, not all compressor series are suitable for all mentioned refrigerants or not all compressor series includes two-stage compressors)

1) Product Information (PI)

Contents

All product information (engineering data) for this series compressor and the corresponding accessories. It is meant to be a guide to the selection of these components.

User group

Project engineers, application engineers, sales managers, product managers for both sales representatives, contractors and end-users.

2) Installation and maintenance manual (IMM)

(Supplied together with the compressor)

Contents

This manual will provide information on how to transport, install, start-up and maintain the compressor (package). It also contains a number of "Product Information Sheets" and the current "Parts List"

User group

To be used in the field by qualified personnel for both sales representatives, contractors and end-users.

3) Service Instruction Manual (SIM)

Contents

Description of (re)assembling, inspection, repair and part or total overhaul of the bare shaft compressor. This manual should be used together with the 'Installation and Maintenance Manual'.

User group

To be used in the field by qualified personnel of contractors.

4) Parts list (PL-xxx) *)

*) per compressor series (xxx)

Contents

All current parts of the compressor together with the design changes (if applicable) to previous supplied components ("History").

User group

Service and parts departments for both sales representatives, contractors and end-users.

5) Parts list (PL-Acc)

Contents

All current parts of the accessories together with the design changes (if applicable) to previous supplied components ("History").

User group

Service and parts departments for both sales representatives, contractors and end-users.

6) Service & Maintenance Schedules

Contents

Service and maintenance schedules up to the date of required overhaul of the bare compressor.

User group

Service and parts departments and in the field by qualified personnel for both sales representatives, contractors and end-users.

7) Instructions for accessories

(Supplied together with the compressor)

Contents

All the relevant mounting and installation instructions and spare parts information for those accessories supplied with the compressor.

User group

To be used in the field by qualified personnel for both sales representatives, contractors and end-users.

8) Directives

Equipment supplied according to Pressure Equipment Directive (PED 97/23/EG) regulations and Machine Directive (MD 2006/42/EG) regulations.

The applied standards are:NEN-EN-IEC 60204, NEN-EN-ISO 12100, NEN-EN-ISO 13857, NEN-EN 378

- 9-Reciprocating Compressors for industrial refrigeration / Series Grasso 6

1. DESCRIPTION AND SELECTION OF

COMPRESSOR

PI2010/v007

1. DESCRIPTION AND SELECTION OF COMPRESSOR

1.1 INTRODUCTION AND SCOPE

1.1.1 OUTLINE

Grasso 6 is the the designation of a series of open, single- acting, reciprocating refrigeration compressors with trunk-type pistons and with 4, 6 and 8 cylinders in resp. V-, W- and VV-arrangement.

1.1.2 TYPE DESIGNATION

The following examples will explain the type designation:

8 cylinder single-stage compressor type

Grasso 86W:8, Number of cylinders6, Series indicationW, Water cooled

1.1.3 APPLICATION

• Industrial operation.• Evaporating temp. between -68 and +22 °C.• Refrigerants: amongst others NH3, R134a, R22,

R404A, R507.• For particular applications (cascade systems, chemical

processes, etc.) consult Grasso.

1.1.4 DRIVE SYSTEM

• Electric motor; direct or V-belt.• Max. speed 1500 min-1.• Rotation normally counter-clockwise when facing

shaft end of compressor. (clockwise is permitted)

1.1.5 SELECTION COMPRESSOR AND ACCESSORIES

Consult Grasso's software program COMSEL (COMpressor SELection) which can be downloaded from Grasso’s internet site.

1.1.6 PRESSURE TESTS

• Test pressure 34.5 bar(e).• Design pressure 24.0 bar(a).• Test run with air.

1.1.7 ACCEPTANCE TEST

• Acceptance test under design conditions, acc. to ISO 917, witnessed by the customer possible on request.

1.1.8 STANDARD SCOPE OF SUPPLY

• Standard bare compressor:� painting pigeon blue� oil and suction filters� Filled with nitrogen� Mating flanges suction and discharge connections� Purge valve on discharge line

Supplied loose:

• Installation and Maintenance Manual(IMM).

Not included:

• oil charge.

1.1.9 OPTIONS

• Lloyds approval (other approvals on request)

REMARK: When the compressor is delivered with a survey certificate it should be taken into account that the fields of application are reduced to a certain extent (viz., somewhat lower discharge pressure = condensing pressure).

• Accessories as mentioned in next chapter.

- 10- Reciprocating Compressors for industrial refrigeration / Series Grasso 6


COMPRESSOR

PI2010/v007



COMPRESSOR

PI2010/v007

1.2 GENERAL DATA

1.2.1 TECHNICAL DATA

Table 1.2-1 Technical Data of Grasso 6 compressors

COMPRESSOR TYPE 46 66 86

Number of cylinders z 4 6 8

Cylinder arrangement 2 x V 2 x W 2 x VV

Cylinder bore D mm 85

Piston stroke S mm 66

Swept volume at full-load: n = 1450/min Vs m3/h 130.3 195.5 260.7

Standard direction of rotationcounter-clockwise when facing shaft end (both

directions permitted)

Standard compressor speeds (with V-belt drive) at motor speed:

1450 min-1

(50 Hz)n min-1 810- 855- 905- 1015- 1140- 1215- 1285- 1450

1750 min-1

(60 Hz)n min-1 800- 875- 980- 1030- 1095- 1225- 1380- 1465

Standard steps of capacity control (expressed in percentage of full load swept volume)

% 100-50 100-67-33 100-75-50-25

Mass of bare compressor (without flywheel and other accessories)

kg 280 345 400

Oil charge in crankcase and oil circuit (centre line of sight glass)a

dm3 9.2 (8.5) 10.0 (9.3) 10.8 (10.1)

Friction power at an 55° C oil temperature n= 1450/min Pw kW 1.10 1.58 2.22

Mass moment of inertia of crank mechanism (without flywheel)b

Id kg.m2 0.0361 0.0421 0.0478

a. The figures between brackets indicate the smaller oil charge for the Grasso 6W compressors due to the presence of an oil cooler.b. The mass moment of inertia Id expressed in SI units, is required to determine the so-called coefficient of speed fluctuation.



COMPRESSOR

PI2010/v007

1.2.2 MAIN DIMENSIONS AND SPACE

REQUIREMENTS

Table 1.2-2

COMPRESSORTYPE

46 46W 66 66W 86 86W

Length A 696 696 721 721 746 746

Width B 840 893 929

C 316 316 379 379 395 395

D 316 316 352 352 363 363

E 189.5 189.5 202 202 202.5 202.5

F 300 300 248 248 228 228

Height G 544 544 644 644 619 619

H 394 394 432 432 444 444

J 60 60 65 65 62 62

K 444 444 482 482 494 494

L 69 69 69

M 155 173 180

N 388 430 446

O 435 328 247

Q 680 660 696

MINIMUM REQUIRED FREE SPACE for removal of:

crankshaft U 661 661 673 673 711 711

piston and cylinder liner

V 260 260 325 325 360 360

W 626 700 748 748 725 725

LOCATION OF CENTRE OF GRAVITY

length Y 225 225 250 250 270 270

width Z 72 72 77 77 67 67

MAIN CONNECTIONS DN (mm)a

suction 1 40 40 50 50 50 50

discharge 2 32 32 40 40 50 50

COMPRESSORTYPE

46 46W 66 66W 86 86W



COMPRESSOR

PI2010/v007

1.2.3 SHAFT END COMPRESSOR

Fig. 1.2-1 Shaft end compressor

1.2.4 SOUND RATING GENERAL

General

The sound characteristics of the compressor series are stated in Lw. Lw is the average measured "sound power level" of the bare shaft compressor block without electrical motor. These values are applicable for the following conditions of operation:• All cylinders in operation (full-load)• All refrigerants• All suction pressures

Sound power-frequency characteristics (Lw)

The sound level table shows the sound power level (Lw, expressed in dB, re 10-12 W) as a function of the octave band centre frequency for all compressor types at

different speeds. The data represent the sound power emitted by the compressor (body) only so excluding the influence of the electric motor and V-belt drive. Each dB-value is the direct or derived result of laboratory measurements according to ISO 9614-1 (Measurement accuracy +/- 3 dB) and carried out by means of latest sound intensity analyzing system Model: Difa, type DSA 220C, software version D-TAC200 3.30 with a Microtech intensity probe SIS90 and Microtech microphones MK290.

Sound pressure level (Lp)

The sound pressure level, at a certain required distance (> 3 mtr.) from the center of the package, can in theory be calculated with the formula: Lp= Lw - 8 -20log R.

Refer to following paragraph.(R = distance form the centre of the package to the required distance in m. (minimum value > 3 m.)

Measured sound pressure level (Lp)

The real measured sound pressure level lies between Lw and calculated Lp level due to the following influence factors: 1) Additional components like oil separators, pipe lines,

type of drive motor etc. can increase the calculated sound pressure level Lp.

2) The acoustic data of the engine room. (These must be known before any calculation can be performed).

3) The stated Lw levels are average levels. It could be that at a certain position (motor, oil separator etc.) higher values can be can be measured

1.2.4.1 SOUND DATA 6

Fig. 1.2-2 Fictional frame

AUXILIARY CONNECTIONS

suction pressure

3

1/4” BSP (plugged off)discharge pressure

4

Oil pressure 5 1/8” BSP (plugged off)

Crankcase pressure

6

1/4” BSP (plugged off)Return from oil separator or

rectifier7

Oil charge and drain valve

8

1/4” BSP (plugged off)Oil

temperature9

Crankcase heater

101/2” BSP female to suit thread of heating

element

Oil leakage drain of rotary

shaft seal11

clanp coupling provided with dia. 6x1 mm steel precision pipe

Water inlet/outlet

(W-types) only12 dia. 19 mm hose connector

a. Provided with a purging and evacuation stop valve type TAH8 (standard on discharge connection and optional on suction connection.

COMPRESSORTYPE

46 46W 66 66W 86 86W



COMPRESSOR

PI2010/v007

Table 1.2-3 Sound power levels Grasso 6 at 12.5 bar and 25.0 bar

1.2.5 STARTING TORQUE

The electric motor driving the compressor should be checked for proper starting.For that purpose the "torque - speed characteristic" of the compressor is needed. This torque Ma, the trend of which is shown in the figure overleaf, is built up of the following components:

Ml = pull-out torque (or break-away torque), required to initiate the movement of the crankshaft after a period of compressor standstill. This torque, only occurring at compressor speed zero, is a constant for each compressor type.

Mw = friction torque, resulting from the purely mechanial losses in the crank mechanism. This torque, acting during the entire starting period at a constant value, only depends on the compressor type and the oil temperature according to the formula:

Mp = pumping torque, pumping torque, due to the flow resistance in the closed loop between the suction chamber and the discharge chambers via the suction valves, discharge valves and the fully opened by-pass valves. This torque is zero at zero speed and increases continuously with speed during the starting period, its magnitude being dependent on the refrigerant, the number of cylinders and the suction pressure according to the formulas:

Mp = (C . po+ D) zd . n2 . 10-8(N.m)where:— C and D are refrigerant constants.— po = suction pressure in bar abs. during starting.— zd = standard number of unloaded cylinders,

determinded by thecompressor type.— n =variable compressor speed in min-1, increasing

from zero to the final nominal speed = design speed.

Mc = Compression torque, required to compress the vapour in the cylinders, which remain loaded during starting. This torque, which can be considered as a

constant during the entire starting period, is determined by the compressor type, the percentage of loaded cylinders, the kind of refrigerant and both the suction and discharge pressure according to the formula:Mc = [(9549 pe / no) - E] zv / z (N.m)

where:— E = compression torque constant.— z = total number of cylinders, determined by the

compressor type.— zv = standard number of loaded cylinders,determined

by the compressor type.no = final nominal (design) compressor speed in min-1.

— pe = full-load shaft power consumption in kW at design speed no and at evaporating temperature to and condensing temperature tc, which both occur during starting. Pe can be found by consulting the software program COMSEL.

The total Ma-curve as a function of the speed n is derived from the components in table below. That means:

— For n = 0:Ma = Mc + Mi — For 0 < n < synchronous design speed no (min-1) : Ma

= Mc + Mw + Mp— The value of Ma for n = 0 drops very quickly with a

smooth transition to the Ma-curve for n > 0.

The Ma-curve, thus obtained, has to be compared with the corresponding torque - speed characteristic of the selected electric motor, as supplied by the motor manufacturer. Keep in mind however, that in case V-belt drive is used, the motor characteristic has to be converted to the compressor shaft by multiplying the torque curve with the transmission ratio D/d, where D and d are the nominal diameters of the flywheel and motor pulley. In the normal case of a squirrel cage motor with star- delta starter, two torque - speed characteristics Mm (Y) and Mm (D) have to be considered as shown in Fig. 1.2-3. The difference between Mm and Ma at any speed (shaded area) represents the torque available for accelerating the combination motor - coupling or

Speed Qty cyl.

Sound power level (Lw), Octave frequencies in Hz

Dischareg presssure 12.5 bar Discharge pressure 25.0 bar

63 125 250 500 1000 2000 4000 8000Overall

level63 125 250 500 1000 2000 4000 8000

Overall level

min-1 - dB dB dB dB dB dB dB dB dB(A) dB dB dB dB dB dB dB dB dB(A)

800

4 86 77 78 56 64 55 - - 72 75 68 76 67 70 45 - - 75

6 75 78 80 65 68 60 - - 75 77 70 77 72 75 50 - - 78

8 70 76 83 74 74 65 - - 78 78 70 78 78 78 60 - - 81

950

4 75 77 78 73 72 62 58 50 76 67 73 78 77 72 64 60 47 78

6 73 73 78 77 75 65 60 - 79 70 75 81 81 77 69 65 - 82

8 73 70 78 81 79 72 62 - 82 72 76 83 85 81 75 69 - 86

1450

4 65 77 78 80 75 69 64 - 80 82 78 82 75 77 71 61 - 82

6 72 78 79 82 78 73 67 - 83 84 80 86 81 81 75 66 - 85

8 77 75 80 84 82 78 60 66 86 86 83 91 84 84 80 71 - 88



COMPRESSOR

PI2010/v007

flywheel - compressor, the intersection points I and II indicating respectively the theoretical switch-over speed from star to delta and the final (partially) unloaded compressor speed.

Fig. 1.2-3 Compressor torque and electric motor torque - speed characteristics

1.2.5.1 STARTING TORQUE NUMBERS GRASSO 6

Table 1.2-4

1.2.6 FREE FORCES AND MOMENTS

Free forces and moments are inertia forces and their resulting moments, generated by not fully balanced masses of the compressor main moving parts (crankshaft, connecting rods, pistons).As indicated in the adjacent figure there can be distinguished horizontal and vertical free forces, called H and V respectively, both acting in a vertical plane I, which is perpendicular to the crankshaft centre line at a distance L from the vertical centre plane of the compressor foot on drive end.Likewise, there are horizontal and vertical free moments, called Mh and Mv and respectively acting in a horizontal plane II and a vertical plane III, which both pass through the crankshaft centre line.Each free force and moment consists of a "primary" component (see table below for the different compressor types) with a frequency equal to the compressor speed and a "secondary" component with a frequency of double the compressor speed.

Fig. 1.2-4 Planes

1.2.6.1 DETAILS

COMPRESSOR TYPE 46a

a. Min. capacity control step 50%

46b

b. Min. capacity control step 25%

66 86

Number of cylinders

Total Z 4 6 8

Du

rin

g s

tart

ing

load

ed

Zv 2 1 2 2

un

load

ed

Zd 2 3 4 6

Pull-out torque Mi 13 17 21

Friction torque at 40 oC oil temperature

Mw 11 15 19

Refrigerant constants of pumping torque

R134a C 93.11

D 9.55

R22 C 80.08

D 9.76

R404A C 97.40

D 5.73

NH

3 C 14.55

D 2.95

Compression torque constant

E 7.24 10.05 14.61

Legend

VPI vertical plane I

VPIII vertical plane III

HPII horizontal plane II

F flywheel end of compressor

CF centre line of compressor foot

CL centre line crankshaft

L distance VPI and centre line compressor foot



COMPRESSOR

PI2010/v007

1.2.7 POSITION OF CENTRE OF GRAVITY

General

For the proper design of a concrete compressor foundation or of the vibration-free mounting of a complete compressor-unit on a steel base frame, the following data, among other things, are required:

• Exact position of the centre of gravity of the combination bare compressor-flywheel.

• Free forces and moments, generated by the compressor.

Position of centre of gravity

In figure Fig. 1.2-5 point Zc represents the centre of gravity of the bare compressor. It’s spatial position within the vertical plane through the crankshaft centre line is determined by the two indicated distances a and b, the magnitude of which, in dependance of the compressor type. Zv is the centre of gravity of just the flywheel, mounted on the compressor shaft end. This point is positioned on the crankshaft centre line at a fixed distance of c from the vertical centre-plane of the nearest compressor foot.The resulting centre of gravity Z of the compressor- flywheel assembly lies on the line that connects Zc and Zv, whereby its position is determined by the distances x and y, as indicated in the figure, which can be calculated as follows:x = (aMc - cMv) / (Mc + Mv)and y = bMc / (Mc + Mv)

where: Mc (kg) = mass (weight) of bare compressorand,Mv (kg) = mass (weight) of loose flywheel

Fig. 1.2-5 Position of centre of gravity

1.2.7.1 COORDINATES POSITION OF CENTRE

GRAVITY

Table 1.2-5 Coordinates and weights

1.2.8 TORSIONAL ELASTIC SUBSITUTE SYSTEMS

OF CRANKSHAFTS

Reciprocating compressors are being used more and more frequently in conjuction with internal combustion engines (diesel or natural gas) as prime mover, particularly for heat pump applications.:In such cases, and considering direct coupled units, it is very important to see to it that the combination engine - (flexible) coupling - compressor is checked for torsional vibration.:The calculations concerned are normally carried out by the engine supplier, the packaged unit manufacturer or any other body specialised in this field. For this purpose and as far as the compressor is concerned, the following data are required:

• So-called torsional elastic substitute system of the crankshaft as well as the arrangement and compression sequence of the cylinders. See Table 1.2-6, Fig. 1.2-6

• Harmonic analysis (Fourier analysis) of the shaft torque-crank angle characteristic over one complete revolution under design conditions, both for each individual cylinder and the entire compressor. The resulting harmonic components, determined by their frequency (order), amplitude and phase angle, can be provided immediately by Grasso on special request for each particular case, whereby the following information should be stated: compressor type, kind of refrigerant, rotational speed(s), suction

CO

MP

R.

TY

PE

Free force and moments

Distance plain I and centre line

compressor foot L (mm)

Forces H (horizontal) and V (vertical) in (N); Moments Mh (horizontal) and Mv

(vertical) in (N.m)a

a. 1 N = 0.102 kgf = 0.225 lbf; 1 N.m = 0.102 kgf.m = 0.738 lbf.ft.

PrimarySecundary

b

1475 min-1b

b. For different speed n (min-1), all forces and moments have to be multiplied by (n/1500)2

1475 min-1

46

ForcesH 0 321.3

202.5V 0 0

MomentsMh 0 0

Mv 0 0

66

ForcesH 0 340.8

215.0V 0 113.6

MomentsMh 0 0

Mv 0 0

86

ForcesH 0 411.5

227.5V 0 169.5

MomentsMh +4.1 0

Mv -4.1 0

Compressor typea b c Mc Mv

mm kg

Grasso 46 225 72

136

280

54.7Grasso 66 250 77 345

Grasso 86 270 67 400



COMPRESSOR

PI2010/v007

pressure or evaporating temperature and discharge pressure or condensing temperature.

Table 1.2-6

REMARK: - J1 = mass moment of inertia of flywheel or coupling flange. - Diameter of all main journals and crankpins = 60 mm. - Smallest diameter of drive end (elastic part C1 = 50 mm. - Crankshaft material: Nodular cast iron GN60.

Compressor type

Mass moment of inertia (kg.m2)

Torsional stiffness between masses

(N.m/rad)

J2 J2 C1 C2

46 0.0165 0.0165 235,593 1,564.876

66 0.0196 0.0196 229,556 1,111.515

86 0.0224 0.0224 223,819 811,352



COMPRESSOR

PI2010/v007

Fig. 1.2-6 Torsional elastic substitute system

1

90o

60o 60 o

60o

60o

60o

60o

60o

60o

46o

46o

46o

46o

46o

46 o

46o

46o

46o

42o

42o

Ι

Ι

ΙΙ

ΙΙ

ΙΙ

ΙΙ

Ι

Ι

1

1

C1 C2

J1 J2 J3

1

1

1

1

1

1

2

3

4

4

4

4

4

4

4

4

6

8

8

8

3

4

5

5

5

5

5

2

6

6

6

6

6

2

2

2

2

2

2

2

5

3

3

3

3

3

3

3

7 7

7

***



COMPRESSOR

PI2010/v007

1.3 LIMITS OF OPERATION AND FIELDS OF APPLICATION

1.3.1 GENERAL LIMITS AND FIELDS OF OPERATION

GRASSO 6

When operating the compressor, none of the limits of operation as stated in the table below must be exceeded.1

The diagrams overleaf represent the overall fields of application in which the individual operation limits are taken into account.

Table 1.3-1 General limits and fields of operation

1.3.2 PRECISE FIELD OF APPLICATION

The field of application diagrams as shown in this manual can vary slightly from the actual field of application for each particular selection.

The actual field of application is dependent on

refrigerant, type of compressor, speed, suction superheat and partload steps.

Always consult Grasso's software program, COMSEL, to determine the precise field of application for an actual compressor selection.

1. In practice, it is not so much the individual operation limits as combinations of them that are decisive for the conditions under which a compressor may operate. To check the various possibilities in this respect, use should be made of the "fields of application" ).

REFRIGERANT NH3 R22 R134a R404A R507

Compressor speed n min-1min. - 800

max. - 1500

Suction pressure = evaporating pressure =crankcase pressure

a pobar(a)

b

min. - 0.3

max.>=1140 min-1

6.2 6.8 6.26.0 5.8

<1140 min-1 6.8

Evaporating temperature = saturation temperature at suction pressure

to °C

min. - -55.1 -63.8 -50 -68.1 -68.5

max.>=1140 min-1

+10.2 +10.0 +22.6-0.1 -2.0

<1140 min-1 +3.8 +3.0

Actual suction temperature c ta °C min. - -50

Suction superheat Δt °C min. - 0 15

Discharge pressure = condensing pressure d pc bar(a) max. - 24.0

Design pressuree bar(a) - 26.5

Condensing temperature = saturation temperature at discharge pressure

tc °C max. - +59.8 +63.2 +79.5 +55.6 +54.4

Discharge temperature f te °C max. - +155

Pressure ratio per stage (pc/po) g j -min. - 1.5

max. - 10 15

Pressure difference (pc-po) h Δp bar max. - 24

Oil temperature in crankcase i toil °Cmin. - >10oC and > Pcrankcase + 15 K

max. - depending on type of oil, refer Section 1.4

a. 1 bar = 105 N/m2 = 100 kPa = 1.02 kgf/cm2 = 14.5 psi.b. The minimum values of po and to are only of importance for booster applications. In that case the maximum value of to also applies to the saturation intermediate

temperature (tm).For halocarbon refrigerants the maximum values of po and to are based on a density of the suction gas of 30 kg/m3. During start-up and immediately thereafter, po,max. may be exceeded slightly [up to 11 bar(a) max.] and temporarily, but no longer than about 5 minutes. The maximum static crankcase pressure during compressor standstill is 21.5 bar(a).

c. Only of importance for booster application.d. This pressure is also the maximum allowable pre-set value of the HP safety switch.e. This pressure deviates from the so called max. discharge pressure=condensing pressure (allowed during operation) as stated in the table.f. This is the actual discharge temperature, measured directly in the gas flow just above the valves.g. Pressure ratio limits are not absolute but arbitrary values based on practical considerations.h. The standard built-in overflow safety valve(s) between suction and discharge side has been factory-set to 24.5 (+ 10%) bar to prevent advanced opening during normal

operation at Δp = (pc - po) ≤24.0 bar.i. Indicated minimum value is the lowest oil temperature at which compressors are allowed to be started.The maximum oil temperature depends on the operating

conditions of the compressor, the oil type used and (for halocarbon refrigerants only) the solubility of the refrigerant in the oil. A minimum actual oil viscosity of 15 cSt is always required. When using ammonia as refrigerant, the maximum oil temperature will be exceeded only when a combination occurs of high ambient temperature, high suction superheat and part-load operation. In that case an oil cooler is required. A water-cooled oil cooler always forms part of the standard delivery of a Grasso 6W-compressor.



COMPRESSOR

PI2010/v007

1.3.3 FIELDS OF APPLICATION

Fig. 1.3-1

Legend

AThis part of the general field of application is not covered by COMSEL. Consult Grasso to make a selection

for this applicaction



COMPRESSOR

PI2010/v007

1.3.4 LIMITATIONS OF PART-LOAD OPERATION

General

For continuous minimum part-load (without cylinder head water cooling) (i.e. more than 30minutes) consult Grasso.

In the case of an Grasso 6-compressor and NH3, operating continuously at part-load, the general field of application is reduced in the sense that for each step of capacity reduction the limit line for Te = 155 oC moves to the right as shown in Fig. 1.3-2, by four Vs-indications in percentage.

In case the of an Grasso 6-compressor and NH3 and cylinder head water cooling can be applied (optional), and there are no part-load restrictions. In other words, the general field of application as shown in Fig. 1.3-2, also remains valid for part-load operation down to and including the standard minimum capacity control step of Vs = 25%.

Fig. 1.3-2 Field of applications for compressor type Grasso 6 with NH3 (upper graphic) and Grasso 6 with NH3 and water cooled cylinder heads (lower graphic)



COMPRESSOR

PI2010/v007



COMPRESSOR

PI2010/v007

1.4 LUBRICATING OILS (CHOICE AND RECOMMENDATIONS)

The choice of oil for a refrigeration compressor should be

made by taking into account the entire refrigeration

system design and operation as well as the operating

conditions of the compressor.

For lubrication of refrigeration compressors, several brands and types of specially developed lubricating oils are on the market. The choice of oil depends not only on its good lubrication properties (viscosity) and chemical stability at the operating conditions of the compressor, but also on the operating conditions of the refrigerating plant (solidifying and floc point, solubility).

Grasso has tested and approved for use in its reciprocating-compressors the brands and types of oil as listed tables below.The choice of the lubricating oil depends on type of refrigerant and the operating conditions of the compressor.The oil viscosity should always be more than 10 cSt.A higher ISO-VG number should be chosen when refrigerant solubility in crankcase is expected to be high especially in case of HCFC’s and HFC’s.

OIL SELECTION PROCEDURE:Use the oil viscosity selection table to select oil viscosity required. The following page lists all oils approved by Grasso for reciprocating compressors.

1.4.1 OIL SELECTION TABLE

Table 1.4-1 Oil selection table

1.4.1.1 REMARKS

1. Using ISO VG100 oils to increase viscosity at high expected cranckcase-temperatures makes no sense as the friction-heat will increase that much, that the oil-temperature limit related to the minimum viscosity of 10 cSt will also be exceeded. Only in case of expected high refrigerant-concentrations in the cranckcase this viscosity-gradeoil is an alternative!

2. Using ISO VG46 oils to meet low pour point requirements is only acceptable if coupled to a high viscosity-index of at least 100, otherwise the working limits are so limited (again concerning the minimum required oil-viscosity of 10 cSt) that it can be used in medium evaporation-pressures, making no sense to use them als a low pourpoint alternative!

Some of the oil types listed in the tables may be marketed under other names and/or designations; these oils can also be used, provided their identity can be proved beyond any doubt. Application of other/alternavive oils is not permitted without the written consent of Grasso.

1.4.2 STRONGLY RECOMMENDED OIL TYPES

Table 1.4-2 Strongly recommended oil types for Grasso reciprocating

compressors

Refrigerant used

Max. allowable evaporating temperature to,max (°C)a

ISO VG-number, according to ISO 3448

46 68 100

NH3 - vb v vb

HCFC’s(R22)

-50 v

-30 v v

-20 v

-10 v v

0 v

+10 v

HFC’s(R134a, R507,

R404A)

-50 v v

-30 v v

-20 v v

-10 v v

0 v

+10 v

For all other refrigerants contact Grasso

Legend v Approved by Grasso

a. to,max is the saturated temperature, corresponding to maximum crankcase pressure where at the usual oil temperatures the oil/refrigerant mixture has a viscosity of > 10 cSt.

b. Refer to Section 1.4.1.1.

Refrigerant used

Brand Type designation

NH3

CPI CP-1009-68

PETRO CANADAReflo 68AReflo XL

Klüber Summit RHT-68

TEXACO Capella Premium 68

SHELLClavus S-68 /

Refrigeration Oil S2 FR-Aa

a. Old name resp. new name; old name will be phased-out during 2010.



COMPRESSOR

PI2010/v007

1.4.3 ACCEPTED NH3 AND HCFC OIL TYPES

Table 1.4-3 Accepted NH3 and HCFC (e.g. R22) oil types for Grasso

reciprocating compressors

1) These oils cannot be supplied anymore from approx. January 2011.

1.4.4 ACCEPTED HFC OIL TYPES

Table 1.4-4 Accepted HFC (e.g. R134a, R404A, R407c, R507) oil types

for Grasso reciprocating compressors

Brand Type designation ISO VG numbera

a. Viscosity grade number designation according to ISO Standard 3448.

AVIAFC 46 44

FC 68 65

BPEnergol LPT-F 46 54

Energol LPT 68b

b. Not miscible with R22 at low temperatures

68

CASTROL Icematic 299 56

CPI CP-1009-68 69

EXXON MOBIL

Zerice S46 48

Zerice S68 68

Arctic 300 68

FUCHSReniso KS 46 47

Renisso KC 68 68

KROON OIL Carsinus FC 46/68 46

PETRO CANADA Reflo 68Ac

Reflo XL

c. NH3 only

58

Kuwait Petroleum Q8 Stravinsky C 55

SHELL

1) Clavus 46 46

1) Clavus 68 68

1) Clavus G 46d

d. For NH3 only possible if water and air are not present!

46

1) Clavus G 68d 68

Clavus S-68 / Refrigeration Oil S2 FR-Ae

e. Old name resp. new name; old name will be phased-out during 2010.

68

1) Clavus G 100d 95

SUN-OIL

Suniso 3.5 GSc 43

Suniso 4 GSc 55

Suniso 5 Gc 94

Suniso 4 SAc 57

TEXACOCapella WF 68 65

Capella Premium 68 67

TOTAL Luneria FR 68 68

Klüber Summit RHT-68 68

Brand Type designationISO VG

numbera

a. Viscosity grade number designation according to ISO Standard 3448.

CASTROLIcematic SW 68 67

Icematic SW 100 100

CPISolest 68 64

Solest 120 131

TOTALACD 68 M 70

ACD 100 FY 98

FUCHSReniso E 68 68

Reniso E 100 100

ICIEmkarate RL 68H 68

Emkarate RL 100H 100

EXXON MOBIL EAL Arctic 68 63

SHELL

Clavus R68 /Refrigeration Oil S4 FR-F 68b 66

Clavus R100Refrigeration Oil S4 FR-F 100b

b. Old name resp. new name; old name will be phased-out from 2010.

94

TEXACO

Capella HFC 55 52.5

Capella HFC 80 80

Capella HFC 120 118



COMPRESSOR

PI2010/v007

1.5 DESIGN DETAILS OF COMPRESSOR

1.5.1 COMPRESSOR HOUSING

The figure below shows the basic construction of the compressors Grasso 6. The additional pos nrs. 29 through 34 shows the construction with water cooling (NH3 only). Water-cooled compressors only differ in an additional (water-cooled) oil cooler incorporated in the crankcase and different (water-cooled) cylinder head covers.

This oil cooler and these cylinder head covers are provided with water in- and outlet connections linked up with each other in series by means of rubber hoses.

The compressor housing of all compressor types are made of cast iron and comprise the crankcase, the cylinder head covers, the inspection side covers, the shaft seal housing on driving side and the bearing cover with built-on oil discharge filter housing on oil pump side. Where the cylinders are located the crankcase has a double wall; the intermediate space is devided by a vertical partition into a suction and a discharge chamber which communicate with the suction and discharge connection respectively, both situated on oil pump side. On this side of the crankcase also a sight glass and an oil charge and drain valve are situated.



COMPRESSOR

PI2010/v007

1.5.1.1 DIAGRAMS GRASSO 6(W)

Fig. 1.5-1 Design of bare compressor Grasso 6(W)

Fig. 1.5-2 Design of bare compressor Grasso 6(W)

Legend

1 Cylinder head cover 9 Oil return check valve

2 Lifting eye 10 Oil sight glass

3 Suction connection 11 Inspection side cover

4 Crankcase heater 30 Cooling water hose

5Suction and discharge

valve assembly31 Water inlet connection

6 Cylinder liner 32 Water outlet connection

7Piston and connecting

rod 33Cast-in channel for cooling

water8 Discharge connection

��

Legend

13 3-way solenoid valve 23 Discharge chamber

14 By-pass slide valve 24 Oil discharge filter

15 Suction chamber 25 Oil filter housing

16 Tube for pressure equalizing 26 Oil pump

17 Rotary shaft seal 27 Bearing cover

18 Crankshaft 28 Oil charge and drain valve

19 Shaft seal housing 29 Oil cooler (water cooled)

20 Oil leakage drain 34 Plug cooling water channel

21 Oil suction filter35

Connection for external oil return line with lubrication oil

pressure regulator22 Crankcase

Legend



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PI2010/v007

1.5.2 CYLINDERS AND MOVING PARTS

The cylinder liners are easily interchangeable and they are made of special cast iron accurately adapted to the running properties of the pistons. The upper collar forms the suction valve seat and is therefore provided with a ring of cast-in slots. To reduce oil carry-over, the cylinder liners are sealed with an O-ring in situ of the passage with the crankcase partition.Each cylinder liner, together with the suction and discharge valve assembly, is retained in the head plate by means of a pressure ring.The connecting rods are made of cast aluminium alloy (the same material as that of the main bearings) and without bearing bushes, thus running direct on both crankpin and gudgeon pin. The connecting rod shank has an oil bore.Specially designed alluminium alloy pistons are provided with two sealing rings and one oil scraper ring and all three are located above the hardened steel gudgeon pin.The two-throw crankshaft of nodular cast iron with cast-on counterweights is supported by two main bearings. The cylindrical driving end with key is intended for the use of clamping sleeve fastening of flywheel or coupling half.Both main bearings are (undivided) bushes, made of special aluminium alloy with outstanding running properties. The one on the driving end is bolted direct into the crankcase, the other one is mounted against the inside of the bearing cover and also serves to fix the crankshaft axially without play and to take up the axial load in both directions. For this purpose, this bearing is retained with both end faces between the crank web shoulder and a disc fitted to the head face of the shaft journal.

1.5.3 ROTARY SHAFT SEAL

For gastight mess between the crankshaft and the outside, the compressor is provided with a rotary shaft seal, the construction of which is shown in Section 1.5.3.1.

Sealing is effected on the lapped sliding surface between a carbon graphite slip ring rotating with the crankshaft and a stationary counter-slip ring, made of special cast iron, fitted in the shaft seal housing.

The counter-slip ring is secured against rotation and sealed against the housing by an O-ring fitted in a groove along its outer circumference.

The slip ring is held in a retainer shell by means of four notches, which on its turn is carried by a driving band with flexible elastomer (neoprene) bellows. The whole assembly can slide axially over the crankshaft and is pressed onto the counter-slip ring by means of a sturdy spring. The bellows also ensures the sealing between slip ring and crankshaft.

To remove the friction heat developed by the slip rings, the shaft seal housing is incorporated in the lubricating oil circuit. Furthermore, the shaft seal housing is provided with an oil leakage drain.

1.5.3.1 DETAILS ROTARY SHAFT SEAL

Fig. 1.5-3

1.5.4 SUCTION AND DISCHARGE VALVES

The suction and discharge valves of the compressor contain valve rings, kept in closed position under spring tension. The lift of the valve rings is limited by the stroke limitor.

The suction valve consists of one valve ring and one or more sinusoidal springs, mounted between the collar of the cylinder liner and the outer discharge valve seat. The collar integrates the suction seats and the valve guide. The discharge valve seat is used as stroke limiter of the suction valve.

The discharge valve consists of one ore more valve seats, valve rings and sinusoidal springs, and a stroke limiter. The valve seats are bolted to the stroke limiter with the central bolt. The whole discharge valve (the so called “discharge valve assembly“) is pressed down by one or more buffer springs, which prevents for serious damage in the case of the presence of liquid in the suction gas.

1.5.4.1 DETAILS SUCTION AND DISCHARGE VALVE

ASSEMBLY

Legend

1 shaft seal housing 8 driving band

2 O-ring 9 supporting ring

3 stationary counterslip ring 10 retainer shell

4 slip ring 11Oil leakage drain of rotary

shaft seal

5 flexible elastomer bellows 12 main bearing bush

6 Spring 13 crankcase

7 spring holder 14oil supply from internal

lubricating circuit in crankcase



COMPRESSOR

PI2010/v007

1.5.5 CAPACITY CONTROL SYSTEMS

1.5.5.1 GENERAL

The capacity control, i.e. the decrease in capacity at constant speed and under constant operating conditions, takes place stepwise by successively cutting out cylinders.This is effected by isolating the discharge space direct above the valves for each individual cylinder head from the common discharge chamber and by putting it into communication with the common suction chamber, located in the compressor housing.This socalled “internal recirculation control” is, (apart from the flow resistance in valves and channels,) free from losses because the cut out cylinders do not

compress gas but just circulate it under suction pressure.

1.5.5.2 DESCRIPTION OF CAPACITY CONTROL

Each controllable cylinder head cover is provided with a by-pass slide valve, which can move horizontally forward and backward in a guide bush and is connected via a push rod to a hot gas operated control piston in a horizontal control cylinder. Slide valve, push rod and control piston form one integral steel part.

Via a three-way solenoid valve , which is mounted outside on top of the cylinder head cover against the sealing cover of the control cylinder, the control piston can be communicated either to suction pressure (via lines c and b, the former connected to the control cylinder and the latter to the by-pass chamber) or to discharge pressure (via lines a and c, the former connected to the permanent discharge chamber in the cylinder head cover).

Actually, only line a, coming from the solenoid valve, is an external one; the two others b and c are internal bores provided in the sealing cover of the control cylinder and in the walls of the cylinder head cover.

1.5.5.3 OPERATION OF CAPACITY CONTROL

If the solenoid valve is not energized, line a is connected via line c to the control cylinder, so that hot gas from the permanent discharge chamber enters this cylinder and, as the diameter of the control piston is substantially larger than that of the slide valve, the combination piston-rod-valve will move to the leftmost position, causing the slide valve to shut off entirely the permanent discharge chamber from the space direct above the discharge valves and the latter to be communicated via a ring of circular openings in the guide bush with the space between control piston and slide valve (by-pass chamber), which is in permanent communication with the common suction chamber in the compressor housing. The cylinder(s) then operate unloaded as a result of the by-pass thus effected.

When the solenoid valve is energised, line b is connected via line c to the control cylinder, so that there is no pressure difference across the control piston and the combination piston-rod-valve is kept in its loaded position by the pressure prevailing in the permanent discharge chamber and exerted onto the righthand face of the slide valve. The space direct above the discharge valves then communicates, via the afore mentioned circular openings in the guide bush of the slide valve, with the permanent discharge chamber, so that the cylinder(s) operate normally.

For the standard capacity control part-load steps of the various compressor types and the corresponding energising sequence of the solenoid valves.

1.5.5.4 PARTIALLY UNLOADED STARTING

In order to be sure that all controllable cylinder always start fully unloaded when there is no pressure difference between discharge and suction, a spring is mounted between each sealing cover and control piston to ensure that all control pistons and slide valves are kept in their unloaded position, regardless of whether the corresponding solenoid valves are energised or not.

Legend

1 central bolt 8suction valve ring with one

sinusoidal spring

2discharge valve stroke

limitor9

discharge valve ring with one or two sinoidal springs accoridng to

high or low temprature operation

3 pressure ring 10 O-ring in crankcase partition

4 sinusoidal buffer spring 11 head plate

5discharge valve seat, also

suction stroke limitor12 crankcase partition

6cylinder liner, also suction

valve seat 13 Peek stroke limitor

7 O-ring



COMPRESSOR

PI2010/v007

On the other hand, to create sufficient discharge pressure to operate all available capacity control slide valves when starting the compressor at zero pressure difference between discharge and suction, at least one cylinder of each compressor type is non-controllable. Consequently, when the discharge pressure is higher than the suction pressure, only partially unloaded starting is possible.Therefore, it is recommended to always check the electric drive motor in this respect, depending on compressor design speed and starting conditions.

1.5.5.5 ALTERNATIVES OF CAPACITY CONTROL

Additional capacity control step for 4-cylinder

compressors;

The four-cylinder compressor can also be delivered with an alternative capacity control, including three part-load steps (25, 50 and 75%) instead of only one (50%) in the standard version.

These additional steps are obtained by replacing the non-controllable cylinder head cover by a partly controllable one of special design, which means that it has a partition in the middle of the space direct above the discharge valves to separate the two adjacent cylinders entirely from each other.So, only one cylinder is always in operation, which has the extra advantage of also reducing the starting load from 50 to 25%.

Compressors without capacity control

On special order, each standard compressor type can also be delivered without any capacity control. In that case not only one but all cylinder head covers are of the non-controllable type, i.e. not provided with built-in control piston and by-pass slide valve.However, the consequence of such a (cheaper) choice is that either fully loaded compressor starting has to be accepted, inevitably resulting in a more powerful electric motor to be installed, or special provisions are to be made by the installer in the field to overcome this inconvenience, for instance by applying an external line with solenoid valve (only open, so energised only during starting) between the suction and discharge line of the installation, combined with a non-return valve in the same discharge line.

Very important installation requirement; To prevent,

during prolonged compressor stand-still, a gradual

pressure equalisation between condenser and

evaporator due to slow leakage of refrigerant gas via the

slide valve, a non-return valve must be mounted in the

external discharge line.



COMPRESSOR

PI2010/v007

1.5.5.6 DIAGRAM CAPACITY CONTROL

Table 1.5-1 Diagram capacity control 1.5.6 CYLINDER HEAD COVERS

For each pair of cylinders viewed lengthwise to the compressor, a cylinder head cover is provided, which feeds the discharge gases to the common discharge chamber in the crankcase via openings in the casting; it further acts as a pulsation damper.

Moreover, and only if the compressor is equipped with standard capacity control, all cylinder head covers except one contain an internal bypass valve, controlled by discharge pressure via an electrically operated three-way solenoid valve.

In case of compressor type Grasso 6W each cylinder head cover is additionally provided with a cast-in cooling water channel, located inside the upper part of the cover over its entire length and consisting of two equal parallel branches, which are connected to each other in series.

Legend Figure on

1 common suction chamber 9 (by-pass) slide valve

2 by-pass chamber 10 guide bush

3 push rod 11 space above discharge valves

4 control cylinder 12permanent discharge

chamber

5 control piston 13 common discharge chamber

6 sealing cover UUnloaded: Cylinders out of

operation, solenoid valve not energised

7three-way solenoid valve

with LED indication(schematic indication) L

Loaded: Cylinders in operation, solenoid valve

energised8 three-way solenoid valve



COMPRESSOR

PI2010/v007

1.5.7 WATER COOLED OIL COOLER

In case of water cooled compressors, the oil cooling is effected by means of a water flow through a steel tube frame, which is fitted onto the inside of one of the inspection side covers and immersed into the crankcase oil sump.The cooling water inlet and outlet connections of the coil, both horizontal and on the same level, are located on the outside of the inspection side cover concerned.The water flows through this oil cooler first and then, in series, through all cylinder head covers.

1.5.8 OVERFLOW SAFETY VALVE AND PRESSURE

EQUALISING

In order to protect the compressor against too high a difference between discharge and suction pressure a spring-loaded overflow safety valve is located in the internal partition between the common discharge and suction chamber.

This safety valve is factory-set at between 24.5 and 27 bar and is accessible after having removed the discharge welding neck flange and thus the entire discharge stop valve, if any.In order to equalise the suction and crankcase pressure and to return the oil entrained with the suction gas, there are three small openings in the partition between suction chamber and crankcase.

Two of these openings are at the lowest level on either side of the suction chamber and are provided with a check valve. The third opening, which is located at the highest level in the middle of the suction chamber, has no check valve but is provided with a small open-ended tube, protruding straight downwards into the crankcase.

1.5.8.1 DETAILS PRESSURE RELIEF VALVE

1.5.9 DIRECT DRIVE OIL PUMP

Table 1.5-2

The direct-driven oil pump, suitable for both directions of rotation, is fitted in the bearing cover, which also comprises the oil suction and discharge chamber.

The oil suction strainer of metal wire mesh (max. opening 315 microns) is immersed in the crankcase oil sump and is only accessible after having removed the inspection side cover.

The oil discharge filter consists of a ring-shaped paper filter element with a filtration rating of 25 microns, retaining the fine (metal) particles suspended in the oil. The direction of the oil flow is from the inside to the outside through the filter element. The filter is fitted with a central stud to the oil pump housing and can be easily replaced from outside by only removing the oil filter housing.

The lubricating oil circuit, accommodated mainly inside the compressor housing. From the oil filter housing the oil flow is forced via a bore in the bearing cover direct into the crankshaft channel for lubricating the main bearings, connecting rods and pistons. Sufficient lubrication of the cylinder walls is ensured by the oil

Legend Figure on

1 crankcase

2 discharge welding neck flange

3 suction chamber

4 discharge chamber

5 pressure relief valve

Legend

1 Oil discharge filter 4 Crankshaft

2 Oil pump element 5 Oil suction filter

3 Oil suction line

Legend Figure on Page 31

��



COMPRESSOR

PI2010/v007

which is being splashed around in the crankcase. The connecting rods have an internal oil channel through which the oil is supplied to the small end bearings.



COMPRESSOR

PI2010/v007

1.5.9.1 OIL LUBRICATION SYSTEM

Fig. 1.5-4

1.5.9.2 OIL CHANNEL

The oil channel in the crankshaft ends in the shaft seal housing from where excess of oil is fed back to the crankcase via an external oil return line. In this oil return line an adjustable lubricating oil pressure regulator is fitted. This spring-loaded ball valve allows the return oil to pass at a certain pre-set pressure only, thus determining the pressure in the lubricating system.Besides the oil return connection on top of the shaft seal housing also an connection for the lubricating oil pressure safety switch is provided.

1.5.10 MAIN CONNECTIONS AND SUCTION GAS

STRAINER

The main connections (suction and discharge) consist of a welding neck flange and are fitted on the oil pump side of the compressor housing by means of bolts.The suction connection communicates with the ample suction chamber in the crankcase upper part via a built-in single, cylindrical suction gas strainer of woven mesh with a filtration rating of 140 microns.

This filter is accessible only after having removed the suction welding neck flange and thus the entire suction stop valve, if any. However, to avoid this operation, a special device (elbow adapter) is available as an accessory.

The discharge connection is located on the same level as the suction connection and is in direct communication

with the common discharge chamber in the crankcase.

1.5.10.1 DETAILS SUCTION GAS STRAINER

Legend

1 Oil suction filter

7Oil lubrication pressure

regulator2 Oil pump

3 Oil discharge filter

4 Thrust bearing 8 Oil sump

5 Crankshaft A Oil lubrication pressure

6 Oil return line B Crankcase pressure

Legend

1 Crankcase

2 suction welding neck flange

3 suction chamber

4 strainer element

��



COMPRESSOR

PI2010/v007



ACCESSORIES

PI2010/v007

2. DESCRIPTION AND SELECTION OF ACCESSORIES

2.1 PART-LOAD POWER CONSUMPTION AND ALLOWED PART LOAD STEPS COMSEL

To determine the allowed partload steps for the design conditons and the corresponding partload power consumption refer to software program Comsel.

2.2 CYLINDER NUMBERING

Fig. 2.2-1 Cylinder numbering Grasso 6

Legend/explanation Fig. 2.2-1

4W(25%) Grasso 46 Watercooled

incl. optional 25%, refer "Additional capacity control

step for 4-cylinder compressors;" on Page 29



ACCESSORIES

PI2010/v007

2.3 CAPACITY CONTROL

Table 2.3-1 Capacity control steps without water cooling

Table 2.3-2 Capacity control steps WATER COOLED

Qyt

Cylin

ders

Cap

aci

ty %

Cylin

ders

So

len

oid

s

450 1 + 3 -

100 1 + 2 + 3 + 4 A

4(25%)a

a. Optional (refer to Section 1.5.5.5)

25 3 -

50 1 + 3 B

75 2 + 3 + 4 A

100 1 + 2 + 3 + 4 A + B

6

33 1 + 4 -

66 1 + 2 + 4 + 5 B

100 1 + 2 + 3 + 4 + 5 + 6 A + B

8

25 1 + 5 -

50 1 + 3 + 5 + 7 B

75 1 + 2 + 3 + 5 + 6 + 7 B + C

100 1 +2 + 3 + 4 + 5 + 6 + 7 + 8 A + B + C

Qyt

Cylin

ders

Cap

aci

ty %

Cylin

ders

So

len

oid

s

450 2 + 4 -

100 1 + 2 + 3 + 4 A

4(25%)a

a. Optional (refer to Section 1.5.5.5)

25 4 -

50 2 + 4 B

75 1 + 3 + 4 A

100 1 + 2 + 3 + 4 A + B

6

33 3 + 6 -

66 2 + 3+ 5+ 6 B

100 1 + 2 + 3 + 4 + 5 + 6 A + B

8

25 4 + 8 -

50 2 + 4+ 6+ 8 B

75 2 + 3+ 4 + 6 + 7 + 8 B + C

100 1 +2 + 3 + 4 + 5 + 6 + 7 + 8 A + B + C



ACCESSORIES

PI2010/v007

2.4 CONTROLS, SAFETIES, GAUGES AND SWITCHES

2.4.1 CONTROLS SINGLE STAGE

In case the compressor will be controlled by a micorprocessor-based control device, the pressures, temperatures, switches and solenoid valves as mention in the picture below have to be controlled.

Fig. 2.4-1 Controls for single stage compressors

Table 2.4-1 Legend single stage control system

2.4.2 “GSC OP” AND “GSC TP” CONTROL DEVICE

Fig. 2.4-2 GSC OP (Left), GSC TP (Right)

General

The “GSC TP” includes a “Touch Panel” (recommended) while the “GSC OP” includes an “Operating Panel”

The GSC TP/OP consists of the control unit with operator keypad and display unit, indicator lights for "Running", "Warning" and "Alarm", emergency stop button, output relays as well as the housing.The standard version of the GSC TP/OP for Grasso packages with reciprocating compressors is installed separately next to the package.

The GSC TP/OP performs the following standard

functions

• Display of all important physical and technical parameters, e.g. pressure, temperature, motor current, capacity, number of hours run, operating mode and status signals

• Automatic start up and shut down of the compressor unit and capacity regulation dependent on the suction pressure or an external temperature

• Monitoring of all operating parameters • Compressor capacity limitation, in case the discharge

pressure, suction pressure, secondary refrigerant temperature or motor current limits are approached

• Alarm memory with date and time • Wire failure detection for all analogue input signals• Password protection for preventing unauthorised

access to important parameters

1 Compressor

3 Oil separator

4 Suction pressure header

7 Discharge pressure header

8 Oil pump

9 Oil pressure regulator

10 Solenoid valves for capacity control

11 Capacity control mechanism of the compressor

12 Crankcase oil level switch

13 Cylinderhead temperature sensor

14 Compressor drive motor

16 Solenoid valve oil return protection

19Dependant on type of oil separator:

oil level float switch (19a) or optical oil level switch (19b)

B To capacity control mechanism of the compressor



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• MPI or Modbus RTU communication with a master controller

• GSC TP (Touch panel)— 10 Minutes Trend values with display for all actual

values, existing directly before alarm shutoff— Remote access vai Ethernet connection (TCP/IP)

• GSC OP(Operating panel)— Freeze display with display of all current values

just before appearance of the last alarm that results in the compressor to shut down

Optional functions

• Control of the packege by a master controller, via potential free contacts

• Frequency-controlled compressor drive motor• Motor current sensor• Remote setpoint adjustment (analogue signal)• Profibus DP-communication• Sequence control (master/slave)

2.4.3 MECHANICAL SAFETY SWITCHES IN

ADDITION TO MICRO-PROCESSOR-BASED

CONTROL SYSTEMS

Table 2.4-2 Pressure safety switches NH3 , Halocarbons and R744

2.4.4 PRESSURE GAUGE AND SAFETY SWITCH

PANEL

General

For checking the correct operation and protecting the compressor and installation, Grasso can supply a pressure gauge and safety switch cabinet as a standard accessory, complete with gauges and safety switches to indicate and control the suction (LP), discharge (HP) and oil (differential) pressure.

Description of cabinet

The fully enclosed cabinet, made of thin steel sheet, contains three pressure gauges mounted in the bevelled upper part of the front panel and two or three (one additional) pressure switches located inside the cabinet

and easy accessible via the removable vertical part of the front panel.This cabinet is suitable for wall mounting by using two holes in the rear panel as well as for floor mounting by using the lower extension of the two side panels. Next to each gauge a text is applied indicating suction, discharge or oil pressure in five languages, viz. : English, German, French, Spanish and Dutch.All internal pressure lines, interconnecting the gauges and switches, are factory-fitted; mounting of the four external lines from the bottom plate of the cabinet to the appropriate pressure connections on the compressor (refer to dimensioned sketches in fig. Fig. 2.4-3and table Table 2.4-3), as well as all electric wiring, remain to be carried out by the installer (on site).

There are two cabinet versions available: one with two safety switches and one provided with three safety switches to meet German UVV-VBG20 regulations.

Description of pressure safety

switchesa

Application

Type

Range of pressure

setting (bar (e))b

Range of contact

differential pressure (bar)

Remarksc

StandardEN378-2

TÜV

Sin

gle

sta

ge

Bo

ost

er

Tw

o s

tag

e A

B

Tw

o s

tag

e C

D

Sin

gle

sta

ge

Bo

ost

er

Tw

o s

tag

e A

B

Tw

o s

tag

e C

D

Number of switches

1 1 1 2 2 2 2 4

Low stage discharge

[Max.]

x x x x RT 30AB 1 .. 10 0.4 fixedpressure limitor switch, locking device, external

reset, protection class IP54

x x RT 30AS 1 .. 10 0.4 fixedpressure safety switch ,

locking defice, internal reset, protection class IP66

High stage discharge

[Max.]

x x x x x xRT 6AB

orC4-P808H-S1B-B0-SEd

10 .. 28or

4 .. 170d1.5 fixed

pressure limitor switch, locking device external


x x x

RT 6ASor

C4-P808H-S1B-B0-SE-X2d

10 .. 28or

4 .. 170d1.5 fixed

pressure safety switch, locking device, internal


a. When mounted on a panel all pressure connections of the safety switches are provided with a clamp coupling for ø6 x 1 mm steel precision tube.b. 1 bar = 105 N/m2 = 100 kPa = 1.02 kgf/cm2 = 14.5 psi.c. Protection class of enclosure according to IEC 144 and DIN 40050. Some of the safety switches are provided with a locking device so that, when cut out, the

compressor does not become operative automatically on return of the original pressure. To unlock, an external or internal reset button is used but only after the reason for cut-out has been investigated.

d. For R744 only.



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REMARK: In case a pressure gauge and safety switch cabinet is not ordered as an accessory, the compressor delivered can optionally be equipped with an oil differential pressure safety switch, Danfoss MP55, mounted on to the crankcase and properly connected, but not adjusted.

Fig. 2.4-3 Pressure gauge and safety switch cabinet

Description and survey of pressure gauges (see also

table Table 2.4-3)

These so-called Bourdon-gauges are glycerine-filled to reduce the vibration of pointer and internal components due to pressure fluctuations and/or external mechanical vibrations. The stainless steel gauges are of a high quality, protected against overloading and intended especially for industrial use.All gauges indicate the pressure in bar(eff.) and all but the oil pressure gauge also indicate the corresponding saturation temperature in 0C.

Description and survey of pressure switches (see also

table Page 40)

• The combined suction and discharge pressure safety switch protects the compressor and plant against too low a suction pressure and excessive discharge pressure.In case the suction pressure drops to below the low pressure pre-set value minus the pre-set differential pressure (LP safety switch) or the discharge pressure exceeds the high pressure pre-set value (HP safety switch), the control current circuit is

interrupted and the compressor stops. Standard “Danfoss” type KP15(A).

• The oil differential pressure safety switch protects the compressor against too low a lubricating oil pressure and reacts to the difference between oil pressure and crankcase pressure (=suction pressure).The oil pressure switch incorporates an automatic time lag relay to bridge the main contacts during start-up. The delay of 60 seconds allows the compressor to built up a sufficient lubricating oil pressure. If during operation of the compressor, the differential pressure decreases, the control current circuit of the motor will be interrupted with a delay of 60 seconds. Standard “Danfoss” type MP55(A).

• Alternative suction pressure safety switch, “Danfoss” type KP1(A) and combined discharge pressure safety switch, “Danfoss” type KP 7(A)BS, suitable for e.g. German UVV-VBG20 regulations.1 One part of the combined discharge pressure safety switch has the function of pressure limitor and the other part acts as a real safety device. The pressure lines of this switch should be connected directly (= without stop valve) onto the compressor. Both alternative switches are available on special order only.

All safety switches mentioned before are provided with a locking device so that, when cut out, the compressor does not become operative automatically on return of the original pressure. To unlock, an internal or external reset button is used but only after the reason for cut-out has been investigated.A wiring diagram showing the internal electrical connections is glued to the inside of the front cover of each pressure safety switch, while a leaflet with further “Danfoss” instructions is placed behind the front cover.

Table 2.4-3 Survey of pressure gauges

1. Keep in mind that the setting of the switches should be so that the maximum pressure difference of 24 bar between the discharge pressure (= condensing pressure) and the suction pressure (= evaporating pressure = crankcase pressure) should not be exceeded.

DescriptionRange (bar

(e))a

a. 1 bar = 105 N/m2 = 100 kPa = 1.02 kgf/cm2 = 14.5 psi.

Temperature range ( OC)

R22 NH3

Suction pressure gaugeb

b. According to German UVV-VBG20 regulations the scale of the suction and discharge pressure gauge has to be provided by the contractor with a red line indicating the maximum operating pressure.

-1 to 12 -70 / +34 -60 / +34

Discharge pressure gauge -1 to 25 -70 / +63 -60 / +34

Oil pressure gauge -1 to 12 -



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Table 2.4-4 Survey of pressure safety switches

Description of pressure safety

switchesa

a. When mounted in a cabinet all pressure connections of the safety switches are provided with a flare coupling for Ø6 x 1 mm copper precision tube.

Typ

e

FunctionR

an

ge b

ar

(e)b

b. 1 bar = 105 N/m2 = 100 kPa = 1.02 kgf/cm2 = 14.5 psi. 7

Contact diff.

press. (bar)c

c. Protection class of enclosure IP 33 (according to IEC 529 and DIN 40050).

Remarks

STA

ND

AR

D

Combined suction and discharge pressure

safety switch KP15(A

d)

d. A is for NH3

suction

-0.9

to

7

0.7 (fixed)

separate locking device and external

reset for suction and discharge.discharge

6 t

o 3

2

4.0 (fixed)

Oil differential pressure

safety switch

MP55(A

d)

-

-0.3

to

4.5

0.2 (fixed)

locking device,

external reset, internal

time relay.

ALTER

NA

TIV

E

Suction pressure

safety switche

e. Both safety switches together are an alternative for KP15 or KP 15A (e.g. according to German UVV-VBG20 regulations).

KP1(A

d)

-

0.9

to

0.7

0.7 (fixed)

locking device,

external reset.

combined discharge pressure

limitor and safety switchf

f. In case a Monitron CR (optional) is applied, this combined pressure limitor and safety switch still remains needed in order to comply with German UVV-VBG20 regulations.

KP7(A

d)B

S

discharge press. limitor

switch 6 t

o 3

2-

4.0 (fixed)

locking device,

external reset.

discharge press. safety

switch

10 t

o 3

2

locking device,

internal reset



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2.5 DIRECT AND V-BELT DRIVE

2.5.1 SELECTION OF DIRECT DRIVE

General

Grasso can supply a complete standard direct drive, consisting of a specially adapted flexible coupling and accessories.

Procedure and data

• Selection: Consult COMSEL.

Standard scope of supply

• Flexible coupling including all parts necessary for mounting and securing.

Options

• Drive guard acc. to CE.• Tool for removing coupling from shaft.• Tool for alignment

Fig. 2.5-1 Flexible coupling

Fig. 2.5-2 Dimensioned sketch of direct drive

Table 2.5-1 Coupling data

2.5.2 SELECTION OF V-BELT DRIVE

General

Grasso can supply a complete V-belt drive system.

Procedure and data

• Selection: Consult COMSEL or graphs below

Legend Fig. 2.5-1

X Distance compressor foot - Motor shaft

Y Distance compressor foot - bolt drive guard

Z1Overall length drive guard, dependant from coupling type, motor frame size and lenght motor shaft end

Z2 Distance fitting bolts drive guard

G Guard

M Motor

C Compressor

Legend Fig. 2.5-2

M Motor

C Compressor

1/2 Coupling half

3 Coupling bolt

4 Coupling element

5 Spacer

6/7 Clamping bush

Type Dimensions in mm Mass moment of

inertia Ik (kg/m2)D1 DV D2 B C E F

42 234 -- 170 46 190 18 62 0.098

61 254 -- 186 76 250 15 68 0.142

91 281 -- 210 76 250 10 78 0.239

61V -- 320 186 76 250 15 68 0.325

91V -- 320 210 76 250 10 78 0.400



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Options

• Flywheel (supplied loose)• Motor pulley (supplied loose)• Set of V-belts (supplied loose)• Drive guard:

� one side protection� two sides protection acc. to CE (mounted for

packages, else supplied loose)

2.5.2.1 DETAILS V-BELT DRIVE

Fig. 2.5-3 Flywheel and drive guard

Table 2.5-2 Flywheel data

Number of grooves 5a

a. To determine the required number of V-belts, refer to the graphs.

Type of Groove SPB

Mass. approx. kg 54.7

Mass moment of inertiab

b. Mass moment of inertia is required to determine the so-called coefficient of speed fluctuation.

kg.m2 1.438

Dimensions (mm)

D (nom.) 400

a 136

b 12.5

c 76

e 77.5

z 71



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Fig. 2.5-4 Selection graph for V-belt drive applicable to 50 Hz motors

Fig. 2.5-5 Selection graph for V-belt drive applicable to 60 Hz motors

2.6 PACKAGED BASE FRAME

General

For mounting on a concrete foundation block, Grasso can supply a standard welded steel base frame to support compressor, motor and accessories.Especially for vibration free operation on floors and on roof tops, a base frame with vibration dampers can be delivered (concrete foundation block can be omitted).

A. BASE FRAME FOR MOUNTING ON CONCRETE BLOCK

(“TRANSPORT BASE FRAME“)

Design Data

• Base frame to be placed on concrete foundation block. For foundation block dimensions consult Grasso.

• There should never be a direct rigid connection whatsoever between the foundation block and the floor or any other main part of the building.

• The concrete block should be extended down to any subsoil.

Scope of supply

• Steel base frame, incl mounting of compressor, electric motor and accessories.

Legend

n Standard compressor speed (min-1)

PMaximum installed motor power (kW) to transmit

(installed motor power)

#V Number of SPB V-belts

S Centre distance flywheel - Motor pulley (mm)

L Pitch length of V-belts (mm)

d Diameter of motor pulley (mm)



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B. BASE FRAME FOR MOUNTING ON VIBRATION

DAMPERS (TORSIONAL STIFF)

Design Data

• Frame to be placed direct on elevated floors and on roof tops (structural floor should be designed to take the weight of the packaged unit).

• Concrete foundation block can be omitted.• The first two pipe supports must be secured to a solid

foundation.• Horizontal piping must be arranged parallel to the

crankshaft of the compressor.• Always consult Grasso for installation advice.

Scope of supply

• Steel closed box profile base frame, including mounting of compressor, electric motor and accessories.

• Set of vibration dampers.



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2.6.1 PACKAGED BASE FRAME

Fig. 2.6-1 Grasso 6 packaged base frame (DD=Direct driven, VD=V-belt driven)

Dimensions

Dimensions and weights, dependent on the package configuration, are available on request.

Frames on vibration dampers

Packaged base frame for mounting on vibration dampers can be determined by Grasso on request.



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2.7 OIL SEPARATOR; OIL RETURN PROTECTION; OIL LEVEL FLOAT SWITCH; OIL EQUALISING AND OIL RETURN

2.7.1 (COMMON) OIL RETURN SYSTEMS

General

Oil return from external sources via suction line of the

compressor is never allowed.

Be sure for a proper connection of the compressor suction line. (Refer Fig. 2.7-1.)

Fig. 2.7-1 Connections common suction line - suction line compressor

2.7.1.1 EXPLANATION OIL RETURN SCHEMATICS

(SECTION 2.7.1.2 AND SECTION 2.7.1.3)

In the case when one compressor and one oil separator is applied the arrangement should be in accordance with the Schematic Oil Return System I, Section 2.7.1.2.The oil from the External Oil Return System (EORS) must be free of refrigerant.If this is not the case then Schematic Oil Return System II, Section 2.7.1.3, must be applied and an Oil Collecting Vessel (OCV) is obligatory.When more than one compressor is installed with a common oil separator and in conjunction with an External Oil Return System the Oil Collecting Vessel is obligatory even when the returned oil is free of refrigerant.The Oil Collecting Vessel (OCV) must be fitted with Oil Temperature Control (TC) to ensure that refrigerant is evaporated thereby eliminating foaming of the oil returning to the crankcase.In case when an OCV is not applied Oil Temperature Control (TC) on the oil separator is recommended.

When an External Oil Return System (EORS) is applied, oil

may only be fed back when the refrigeration plant is

clean, normally after 12 months of operation; Before

returning oil via EORS, an oil analysys has to be done.

Summarized

1. TC (oil return protection)a) Is obligatory in case OCV is appliedb) Is recommended on the oil separator, in case OCV

is not applied and refrigerant is not R7442. LCH (oil level control crankcase compressor)

a) Is obligatory in case EORS is appliedb) Is obligatory in case of more than one

compressors on one common oil separator3. OCV (oil collecting vessel):

a) is obligatory for one or more compressors in combination with EORS and returned oil is not free of refrigerant

b) is obligatory for multiple compressors in combination with EORS, independant if the returned oil contains refrigerant

c) is not required for one compressor, without EORSd) is not required for one compressor, with EORS and

returned oil is free of refrigerant

2.7.1.2 SCHEMATIC OIL RETURN SYSTEM I

For explanation of the application of LC, TC and EORS refer Section 2.7.1.1.

Fig. 2.7-2 Oil return schematic I

Legend (Fig. 2.7-1)

1 Preferred connection

2 Allowed connection, but not preferred

3Connection NOT allowed

4

Legend oil return system I (refer also "Summarized" on )

EORSExternal Oil Return System;

Oil has to be refrigerant free (refer "Summarized" on Page 47)!

OS Oil separator

EVRA3

Solenoid valve

TAE7 Stop valve

TCOil temperature controller (oil return protection, option).

At low temperature solenoid valve is closed;Recommended if refrigerant is not R744.



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2.7.1.3 SCHEMATIC OIL RETURN SYSTEM II

For explanation of the application of LC, TC, EORS and OCV refer Section 2.7.1.1.

Fig. 2.7-3 Oil return schematic II

2.7.2 OIL SEPARATORS

General

Grasso can supply standard oil separators, designed for application in discharge lines (also LP discharge lines for interstage cooling system C and D).

Procedure and Data

• Selection:— Consult Grasso software program COMSEL.


• Oil separator according to CE/PED.• Set of flanges (DIN2635) for inlet connections.• Float valve assembly, for automatic return of oil to

crankcase of the compressor and stop valve (not mounted).

• Oil drain stop valve (not mounted).• Safety valve connection

Options

• Other approvals on request.• Set of flanges (DIN2635) for outlet connections.• Welding mating flanges.• Base support for mounting on concrete floor.• Oil return protection.• Single (1/2” BSP ) safety valve• Double (1” BSP) safety valve (refer Fig. 2.7-4)

Fig. 2.7-4 Double safety valve (optional)

Design data

Table 2.7-1 Oil separator design data

C Compressor

LCHGrasso oil level float switch (optional);

At high oil level, solenoid valve is closed;Obligatory in case EORS is applied.

VC Check valve

H2 Crankcase heater

F Filter (< 50 mu)

Legend oil return system II (refer also "Summarized" on Page 47)

EORS External Oil Return System

OCVOil Collecting Vessel

Obligatory; refer "Summarized" on Page 47.

OS Oil Separator

EVRA3 Solenoid valve

TAE7 Stop valve

TC

Oil temperature controller;At low temperature solenoid valve is closed;

In case OCV is applied, TC is obligatory, otherwise TC on oil separator (oil return protection, option) ;recommended if refrigerant is not R744.

C Compressor

LCH

Grasso oil level float switch (option); At high oil level, solenoid valve is closed;

Obligatory in case EORS is applied OR more than one compressor is connected to one OS.

VCVR

Check valveRegulating check valve

H1 Heater OCV

H2 Crankcase heater

F Filter (< 50 mu)

Legend oil return system I (refer also "Summarized" on Page 47)

OS3 OS4 OS5 OS6 OS8

Weight (kg) 114 190 278 466 600

Contents (dm3) 70 126 230 379 632

Oil charge (dm3) 6 13 16 22 16

Design pressure (bar(e)) 26.0

Test pressure (bar(e)) 42.9

Design temperature -10 ... +170 oC



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Legend (refer Fig. 2.7-5 and Fig. 2.7-6)

1 Inlet connection

2 Outlet connection

3Set of flanges (the inlet flange is standard included, the outlet

flange is optional)

4 Stop valve (type TAH8) for oil return to crankcase

5 Connection for temperature transmitter

6 Float valve

7 Stop valve (type TAH8) for oil drain

8 Base support (optional)

9 Dirt drain

10 Safety valve connection (1/2” BSP)



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Fig. 2.7-5 OS series, types OS3, OS4, OS5 and OS6



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Fig. 2.7-6 OS series, type OS8

2.7.3 OIL RETURN PROTECTION

General

Grasso can supply an oil return protection system, to prevent excessive foaming of oil in crankcase, which can occur when starting the compressor after a long period of standstill with relatively low oil temperature. (refer also to accessory 'crankcase heater')

Selection and Data

• The minimum oil return temperature of the thermostat has to be set at approx. > Tc + 5 K and > 40 oC.

• Solenoid valve is always closed during compressor standstill.

• Sensor to be connected to float valve connecton of oil separator.


• Solenoid valve.1

• Thermostat with sensor(ref. Fig. 2.7-8) or PT1000



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Options

For packages with built-on oil separator(s):• Mounting

Fig. 2.7-7 Oil return protection

Fig. 2.7-8 Thermostat with sensor

2.7.4 CRANKCASE OIL LEVEL SWITCH

General

In case two or more compressors operate in parallel on one common oil reservoir or oil separator, Grasso can supply an oil level switch.

Selection and Data

• To be fited on crankcase• Auxiliary relay required (not included)• Wiring: If 'Low oil level' and 'Compressor is running'

then 'solenoid valve open'


• Oil level switch

Options

• Mounting

Fig. 2.7-9 Float switch wiring diagram

Table 2.7-2 Legend

2.7.4.1 DETAILS CRANKCASE OIL LEVEL FLOAT

SWITCH

1. This solenoid valve can also be used in combination with an oil level float switch (refer Section 2.7.4)

Legend oil return protection

C Compressor

OR Oil return linea

a. Oil return via the suction line is not allowed!

V1 Solenoid valve

TC Thermostat

TT Temperature transmittor

OS Oil separator

Legend (dimensions in mm)

CL Cable length

1 Oil level float switch

2 Auxiliary relay (not included)

3 Solenoid valve (not included)

4 Oil return from oil separator or liquid rectifier

N Neutral

L Live



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Fig. 2.7-10 Crankcase oil level float switch

Legend

A Float switch housing

B Oil level float switch

C Oil sight glass



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2.8 WATER COOLED CYLINDER HEADS AND COOLING WATER REQUIREMENTS

General

Grasso can supply a cylinder head water cooling system(refer to Section 1.5.6) in combination with a water cooled oil cooler(refer to Section 1.5.7 and Fig. 1.5-2), in order to maintain the field of application in partload for NH3.(refer to Section 1.3.4)

Effect of water cooling

In order to avoid the part-load limitations as shown in the field of application in Fig. 1.3-2(upper), water cooling should be applied, in which case a much more favourable field of application is obtained, as shown in Fig. 1.3-2(lower).Water cooling means cylinder head cooling in combination with oil cooling.Even during full-load operation the overall compressor housing temperature will be favourably influenced by applying water cooling, however, without enlarging the original total field of application for compressors without water cooling.

Application requirements

The water cooling system, consisting of special cylinder head covers, a crankcase oil cooler and the interconnecting rubber hoses, as described in chapter 2, has been designed for a maximum water pressure of 6 bar.

Table 2.8-1Table 2.8-1 below gives an approximate indication of the amount of cooling water required at a water inlet temperature of 40 oC.The actual water flow for different values of twi and depending on the operating conditions to and tc (evaporating and condensing temp.) should be such, that the crankcase oil temperature does not exceed 80 oC and the discharge gas temperature, measured at the compressor discharge connection, is not higher than tc + 75oC.

Table 2.8-1

It is recommended to apply a closed water recirculation system via a separate heat exchanger in order to prevent deposits inside the cooling water channels which could restrict the free flow of water.The cooling water used should be non-aggressive (not causing corrosion, e.g. sea water or brackish water should not be used at all) and with an water inlet temperature not lower than 10 oC in order to prevent premature condensation of refrigerant

in the cylinder heads which may result in liquid hammer and possible damage to the compressor.Furthermore the max. water inlet temperature of 45 oC and water outlet temperature of 70 oC should not be exceeded.

Provision should be made to interrupt the waterflow when the compressor stops, preferably by means of a solenoid valve.During long periods of compressor standstill at low ambient temperatures the cooling water should be drained off from the cylinder heads and oil cooler or an anti-freeze agent should be added to the cooling water in order to prevent freezing of the cooling water.

2.9 CRANKCASE HEATER

Recommended for all compressors and all conditions of operation.

General

During standstill of the compressor, refrigerant may dissolve in the oil charge of the crankcase or it may even condense, both due to an increase of crankcase pressure, a decrease of crankcase temperature and/or possible temperature differences between crankcase and evaporator.

Excessive foaming of oil in crankcase, can occur when starting the compressor after a long period of standstill with relatively low oil temperature which may result in damaging the compressor by a lack of lubrication.

Low oil temperatures may also cause a high oil viscosity, which may result in troublesome starting.

Selection and Data standard heater

• Refer to table.• Engine room temperatures below 20 °C.• Wiring: If 'compressor NOT running' then 'element is

energised'.


• Heater element (mounted, not wired).

Fig. 2.9-1 Standard crankcase heater

Number of cylinders

Cooling water required in m3/h at tw = 40 0C (approx.)a

a. Depending on operating conditions To and Tc

min. max.

4 0.18 0.36

6 0.24 0.48

8 0.30 0.60

Legend

CE Cable entry

RC Removable cap to protect connections



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Mentioned power in Watt; Standard voltages are 110-120 V and 220-240 V.

2.9.1 DETAILS CRANKCASE HEATER

This standard crankcase heater is thermostatically controlled.

2.10 STOP VALVES, CHECK VALVES AND FLANGES SUCTION AND DISCHARGE CONNECTIONS

Refer to “Main Dimensions and Space Requirements” to determine DN connections

General

Grasso can deliver (straight through) stop valves to suit suction and discharge connections.It is strongly recommend to apply suction and discharge stop valves.


• Stop valves (not mounted)

Options

• Additional set of flanges (not mounted)• Check valves for discharge connections (not

mounted)• Welding stop valves, check valves and mating flanges

2.11 HAND-OPERATED OIL PUMP


• hand-operated oil pump• charging hose

Fig. 2.11-1 Hand-operated oil pump

Don’t use the oil drain valve of the compressor.

Installed power of heater element

Dimension L (mm)

400 400

Legend

a Oil charge valve, located on the oil pump of the compressor



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