reed berinato jaharis center

Reed Berinato Mechanical Option

Jaharis Center Boston, MA

Mechanical Systems Existing Conditions

November 12, 2004

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Mechanical Systems Existing Conditions November 12, 2004

Contents

Executive Summary................................................................................. 2 Existing Conditions Evaluation............................................................ 3 Design Objectives and Requirements................................................... 3 Site Factors Influencing Design Decisions........................................... 4 Outdoor and Indoor Design Conditions................................................ 4 Design Heating and Cooling Loads....................................................... 5 Energy Sources and Rates...................................................................... 6 Conceptual Description of System Operation....................................... 6 Chilled Water......................................................................................... 7 Steam..................................................................................................... 8

Hot Water.............................................................................................. 8

Critique of System................................................................................... 9 Appendices................................................................................................ 10 Appendix A – Mechanical Equipment Schedules.................................. 11 ● Supply Air Handling Unit Schedule 12 ● Exhaust Air Handling Unit Schedule 13

● Double Effect Steam Absorption Chiller Schedule 17

● Finned Tube Radiation Schedule 13 ● Air Distribution Device Schedule 14

● Centrifugal Chiller Schedule (High Efficiency) 17

● General Fan Schedule 14 ● Cooling Tower Schedule 17 ● Variable & Constant Volume box Schedule 16 ● Water Pump Schedule 18

Appendix B – Mechanical System Flow Diagrams…......................... 19 ● HVAC Legend (Symbols) 20 ● Chilled Water Flow Diagram 21 ● Condenser Water Flow Diagram 22 ● Steam Flow Diagram 1 of 4 23 ● Hot Water Flow Diagram - Radiation Loop 24 ● Hot Water Flow Diagram – Reheat Loop 25

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Executive Summary

The Scope of this assignment is an analysis of the existing mechanical systems in

The Jaharis Center for Biomedical and Nutritional Research at Tufts University in

Boston, Massachusetts. Schedules of existing equipment along with schematic drawings

of system components were constructed using mechanical system design drawings and

specifications provided by BR+A Consulting Engineers, Inc. For this report, emphasis

was placed on the system as a whole, instead of individual components of the system due

to the integration among the air handlers in this design. No information regarding cost

was provided by my sponsor. Also, an operating history could not be acquired for this

project because it is not currently 100% complete. The schematic drawings are

incorporated into the LOGIC discussions. Space requirements, design loads, site factors,

and system operation are discusses as well as a critique of the system. Data and findings

from previous assignments are incorporated in these discussions. Finally, an overall state

of design and function discussion concludes this technical report.

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Design Objectives and Requirements

Design objectives for the Jaharis Center vary from level to level. However this

building can be divided into three main use categories which consist of classroom, office

and laboratory spaces. The basement level through level three are dominated by office

and classroom space with only a small percentage of level three having laboratories,

while levels four through nine are intended to be mostly laboratory space, but are not yet

fit out due to the lack of space design requirements. A design objective for this

configuration was having separate air handling systems for these two main divisions.

The laboratory space HVAC design is based heavily on human occupancy due to all

heavy equipment having its own dedicated space and/or stand alone exhaust. Also, the

laboratory space is required to have a 100% outdoor air supply. The design of the lower

levels is weighted entirely on human occupancy, so design is prescribed by ventilation

requirements, and individual space loads. A large mechanical penthouse is required for

this project due to the structure’s relatively small footprint and lack of available room in

the basement level.

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Site Factors Influencing Design Decisions The site for the Jaharis Center had a great deal of influence on the fundamental

elements of the mechanical system design. Since its location is in the heart of downtown

Boston, intake and exhaust louvers had to be located at a level far enough above the street

as to not influence the street level air quality and noise intensity or compromise the

security of the building’s ventilation system. Due to the Jaharis Center being located on a

university campus, a stem supply is readily available, adding to the convenience of a

steam absorption chiller. The location of this building is in the northeast of the United

States which makes heating a focus of the mechanical system, although cooling will be

required throughout the year.

Indoor and Outdoor Design Conditions Outdoor design conditions were taken from the ASHRAE Handbook:

Fundamentals 2001. Specific location climatic design data was taken from chapter

27.12-27.13 Tables B1 and B2. The winter design dry bulb temperature is 7ºF (99.6%.)

The summer design temperatures are 87ºF dry bulb and 71ºF wet bulb. (1%.) The indoor

design conditions are typically 75F dry bulb at 50% relative humidity. However, there

are cold and warm rooms inside the laboratory served by the central hot water and cold

air systems that have special design requirements.

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Design Heating and Cooling Loads

Design cooling loads are given for each air handler. Load calculations were not

provided by the designers, but individual coil capacities are given. Independent load

calculations were performed using the Carrier program: HAP v4.1 with a resulting

cooling load of 618 tons. A chart of cooling load distribution can be found below.

Terminal reheat and perimeter heating are the primary means of heating. The AHU’s

only heating coils are a heat recovery loop and a steam preheat coil. The table below lists

the Pre-heat coil capacity in the air handlers. All air handlers are identical.

Unit Designation Cooling Capacity (MBH) Heating Capacity (Min MBH)

AHU - 1 5408 4158 AHU - 2 5408 4158 AHU - 3 5408 4158 AHU - 4 5408 4158

Computer Based Modeling Load Distribution

Occupant Latent4.1% Equipment

5%

Occupant Sensible

4.1%

Envelope3.3%

Lighting7.9%

OASensible

14.9%

OALatent37.4% Supply Fan

18.8%

Duct Heat Gain 1%

Zone Conditioning

3.5%

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Total cooling capacity for the Jaharis Center is 1400 tons. This load is divided

between two chillers. The electric centrifugal chiller performs 600 tons of cooling, and

the steam absorption chiller performs 800 tons of cooling. Total heating load is not

available at this time. Heating is accomplished by direct steam heating and hot water

heating, both energy sources originate from the main steam line.

Energy Sources and Rates

The following information on electrical energy rates was provided by my sponsor.

Exact steam cost is not available; however, the average cost for high pressure steam

(125psig) in New England is $5.05 per 1000 lbs. No special rebates or discounts used as

design incentives are known.

Customer Charge $15.23/month Distribution Demand Charge $5.92/kW Distribution Energy Charge 0.084¢/kWh Transmission Charge 0.611¢/kWh Transition Demand Charge $0.67/kW Transition Energy Charge 0.472¢/kWh Demand Side Management Charge 0.250¢/kWh Renewables Charge 0.050 ¢/kWh Total Energy Charge .01467 $/kWh Total Demand Charge $6.59/kW

Conceptual Sequence of Operation

The sequence of operation is described in this section of the report. This is the

operating sequence’s general concept. More detail is involved in the actual operation, but

for the purposes of this report, only the major component function is examined. The

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major building systems described in the following sections include: chilled water, steam,

and hot water. System schematic drawings which are referenced in the sequence

descriptions are located in the appendices of this report.

O Chilled Water The chilled water system is served by two chillers configured to share the load

equally. There is one double effect steam absorption chiller (600 tons) and one high

efficiency electric centrifugal chiller (800 tons.) The water distribution system is

arranged in a primary/secondary configuration. The primary and secondary loops can be

individually balanced and operate independently of each other. The primary water loop

is served by one constant flow, centrifugal chilled water pump (CHP-1) and one standby

centrifugal chilled water pump on a Variable Speed Drive (CHP-3.) Control is provided

by temperature sensors located on the primary chilled water supply and return lines as

well as the secondary chilled water supply and return lines and the common pipe.

Control is provided by the DDC for the primary loop. The secondary loop has a

differential pressure sensor controlling the variable speed drives of the secondary chilled

water pumps. The differential pressure sensor is located at the terminal cooling

equipment in AHU’s 1-4. There is also a differential pressure control valve located on

the secondary loop.

Condenser water for the chillers is provided by two cooling towers located on the

roof. One is a single cell (CT-2) and the other is a double (CT-1.) Condenser water at

95°F is supplied to each of the towers by one constant flow, centrifugal condenser water

pump (CH-1) and a second shared standby centrifugal pump on a variable speed drive

(CH-2.) Make-up water is provided by a make up control valve controlled by the DDC.

Water level sensors located in the basins of the cooling towers initiate the make-up

process.

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O Steam Steam is provided through a 10” line at 125 psig from Trigen Boston Energy

Corp. The sole purpose for the 125 psig steam (HPS) is to provide the double effect

steam absorption chiller (CH-2) with the steam it needs to operate, which is regulated

through a control valve provided and configured by the chiller manufacturer. The HPS is

then reduced in pressure by pressure reducing valves 1 and 2 (PRV-1 and -2) to 60 psig

(MPS.) This 60 psig steam is solely meant to supply laboratory autoclaves located on

levels three, four, eight and nine. The autoclaves are controlled by two-way pneumatic

automatic valves. The MPS is then reduced in pressure to 15 psig (LPS) by pressure

reducing valves 3 and 4 (PRV-3 and -4.) The LPS is now divided into three loops. One

loop serves the pre-heat coils and the humidifiers in AHU’s 1-4, both of which are

controlled by two way pneumatic automatic valves and the DDC. The second loop

serves the hot water heat exchangers for the hot water radiation and reheat loops (HE-1

through HE-3). The heat exchangers are regulated by electric motorized automatic

valves that are controlled by the DDC system which receives temperature data from the

water side of the heat exchangers. The third loop serves eight instantaneous domestic hot

water heaters, each with stand alone individual controls.

The high pressure return (HPR) and the medium pressure return (MPR)

congregate at a flash tank (FT-1) where they are converted into low pressure return

(LPR.) The LPR lines from all loops are fed into duplex condensate pump 1 (CP-1), and

then piped back to Trigen through a 6” pumped condensate line.

O Hot Water There are two hot water loops in this building. One serves all the terminal reheat

coils in the air distribution system, the other serves all the perimeter terminal heating

units in the building.

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The Reheat coils loop is served by heat exchanger 2 (HE-2) with heat exchanger 3

(HE-3) as a standby connected to the system with normally closed gate valves. HE-2

then feeds into a diaphragm expansion tank (T-2) and then into an air separator (AS-2.)

The reheat coils loop is circulated by a centrifugal variable speed drive hot water pump

(HWP-2.) with a second, identical hot water pump (HWP-3) on standby. Control for the

variable speed drive is provided by the air distribution devices through the DDC.

` The radiation loop configuration is identical to the reheat loop except that there is

no back up heat exchanger. The radiation loop is heated by heat exchanger 1 (HE-1) and

is circulated by a pump slightly smaller than that of the reheat loop, but of the same VSD

configuration. Control for the variable speed drive is provided by the perimeter heating

devices through the DDC.

Critique of System

Three main design considerations drove the design of the mechanical system in

the Jaharis Center at Tufts University in Boston, Massachusetts. The first of which plays

a part in the design of almost every HVAC system, and that is first cost. The second of

which is the availability of steam to the building location. With this availability, as most

city’s and college campuses have, the need for boilers is eliminated, and the use of steam

heating coils is made possible. The third design consideration, and possibly the one that

had the most influence is the requirement for 100% outdoor air for the laboratory spaces.

This design requirement resulted in a 100% outdoor air system for all spaces in the

building.

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Other influences in the overall design of the system include the small footprint of

the structure. This made the amount of mechanical equipment located on any one

particular level limited. Fortunately, the architects provided a two story mechanical

penthouse to place mechanical equipment in. This configuration resulted in a total lost

rentable space of approximately 12.8% (Tech. Report 2) of the total building square

footage due to mechanical equipment.

A final influence in the design of this system is the actual design schedule. This

project was started in 1997 where an initial mechanical design was conceived. After that,

the project was put on hold until 2000 when it was rushed through the re-design process.

At this point, not much attention could be paid to system efficiency, and the end result

was a 100% outdoor air design that has some room for improvement.

In summary, the design for this building is a practical, relatively low cost design

that works well for the design schedule. There is, however, room for improvement in

overall system efficiency.

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Appendix A: Mechanical Equipment Schedules

Supply Air Handling Unit Schedule

Unit Number AHU-1 to AHU-4 All Air Handlers are Identical

Unit Location Penthouse Areas served All

Unit Configuration Draw-Through CFM/Fan 35,000 Total S.P. (in. H2O) 9.0 Total Pressure (in. H20) 9.325 Electrical 480V 3-Phase

Supp

ly F

ans

2 pe

r AH

U

Motor – Max. BHP 100 CFM 70,000 Number of Coils 6 ∆P max. (in. H20) 0.8 EAT (°F) 0 LAT (°F) 31.7 A

ir Si

de

Total MBH 2448 Fluid Type 40% Propylene Glycol GPM 455 EWT (°F) 45.4 LWT (°F) 33.6

Hea

t Rec

over

y R

unar

ound

Coi

ls

Wat

er S

ide

∆P max. (ft. H20) 15 CFM 70,000 Number of Coils 2 ∆P max. (in. H20) 0.6 EAT (°F) 0 A

ir Si

de

LAT (°F) 55 Inlet psig 5 Flow (lb./hr.) 4332 Min. MBH 4158

Stea

m P

rehe

at C

oils

Stea

m S

ide

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Supply Air Handling Unit Schedule (Continued) CFM 70,000 Number of Coils 6 ∆P max. (in. H20) 1.3 EAT db/wb (°F) 91 / 75 LAT db/wb (°F) 52.5 / 52 A

ir Si

de

Total MBH / Sensible MBH 5408 / 2910 Fluid Type 40% Propylene Glycol GPM 721 EWT (°F) 44 LWT (°F) 59

Chi

lled

Wat

er

Coo

ling

Coi

ls

Wat

er S

ide

∆P max. (ft. H20) 12 Filter Efficiency % 30 ∆P (in. H20) .5 Size (in.) 24 x 24 CFM 70,000 Pr

e-Fi

lter

Number of Individual Filters 40 Filter Efficiency % 95 ∆P (in. H20) 1.0 Size (in.) 24 x 24 CFM 70,000

Filte

rs

Fina

l Filt

ers

Number of Individual Filters 40 CFM 70,000 °F 72

Spac

e

%RH 30 psig 8 Lbs./hr. 763 H

umid

ifier

s

Stm

.

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Exhaust Air Handling Unit Schedule

Unit Number EAHU-1 – EAHU-4 All Air Handlers are Identical

Unit Location Penthouse Areas served All

Unit Configuration Draw-Through CFM/Fan 35,000 Total S.P. (in. H2O) 9.0 Total Pressure (in. H20) 9.325 Electrical 480V 3-Phase

Supp

ly F

ans

2 pe

r AH

U

Motor – Max. BHP 100 CFM 70,000 Number of Coils 6 ∆P max. (in. H20) 1.1 EAT db.wb (°F) 78 / 62 LAT db/wb (°F) 49.8 / 49.3 A

ir Si

de

Total MBH / Sensible MBH 2468 / 2167 Fluid Type 40% Propylene Glycol GPM 455 EWT (°F) 33.6 LWT (°F) 45.4 ∆P max. (ft. H20) 15

Hea

t Rec

over

y R

unar

ound

Coi

ls

Wat

er S

ide

FPI 8 CFM 70,000 ∆P (in. H20) 0.5

Filte

rs

Pre-

Filte

r

Finned Tube Radiation Schedule Unit No.

Min Cap. BTUH/LFT

AWT °F Pipe Size Fins

/ ft.

No. of Eleme

nts A 1130 190 1-1/4” Copper 33 1 B 1130 190 1-1/4” Copper 33 1 C 910 190 1-1/4” Copper 48 1 D 910 190 1-1/4” Copper 48 1

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Air Distribution Device Schedule Unit No. Service Air Pattern Material

A Supply Air 1-Way Painted Steel B Supply Air 2-Way 90° Painted Steel C Supply Air 2-Way 180° Painted Steel D Supply Air 3-Way Painted Steel E Supply Air 4-Way Painted Steel F Return / Exhaust - Painted Steel G Supply Air - Painted Steel H Supply Air - Painted Steel I Toilet Exhaust - Painted Steel J - Not Used Not Used K Supply Air Double Deflection Painted Steel L Supply Air 1 & 2 Way Painted Steel M - Not Used Not Used N Return / Exhaust 45°Fixed Painted Steel O - Not Used Not Used P Return / Exhaust 45°Fixed Painted Steel Q Supply Air Double Deflection Painted Steel R Return / Exhaust 45° Fixed Painted Steel G1 Supply Air - Painted Steel

General Fan Schedule Motor Data @ 60 Hz Unit

No. Service Location Wheel Diam. in. CFM Tot. S.P.

in. H20 HP Fan RPM V PH EX-1 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-2 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-3 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-4 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-5 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-6 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-7 General Exhaust Roof 50 23,000 6.5 40 1170 480 3

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General Fan Schedule (Continued) Motor Data @ 60 Hz

Unit No. Service Location Wheel Diam. in. CFM Tot. S.P.

in. H20 HP Fan RPM V PH EX-8 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-9 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-10 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-11 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-12 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-13 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-14 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-15 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-16 General Exhaust Roof 50 23,000 6.5 40 1170 480 3 EX-17 Special Exhaust Level 11 21 7000 8 20 2414 480 3

EX-17A Special Exhaust Level 11 21 7000 8 20 2414 480 3 EX-19 Stair No. 1 Roof 21 6600 2 5 1625 480 3 EX-20 Stair No. 1 Wall 16.5 2500 0.5 0.75 1078 480 3 EX-21 - - - - - - - - - EX-22 Mechanical Rm. Level 11 22.5 6000 2 5 1266 480 3 EX-23 Electric Bsmt Level 11 15 1200 2 1.5 2023 480 3 EX-24 Glass Wash Level 11 18 3000 2 3 1511 480 3 EX-25 Penthouse Roof 24.5 5500 0.5 1.5 709 480 3 EX-26 Electric Vault Basement 24 8000 1.5 5 1770 480 3 EX-27 Lvl 11 Elec Rm Level 11 15 2400 0.5 1 1923 480 3 SF-1 Electric Vault Basement 24 8000 1.5 5 1770 480 3

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Variable and Constant Volume Box Schedule Hot Water Coil

Unit # Type Design Range CFM

∆P max. (in. H20) MBH GPM

Inlet Duct Size (in.)

Outlet Duct Size

(in.) VCV/CV-6 V/C Volume 75-400 0.7 19.4 0.7 7 12 x 10 VCV/CV-8 V/C Volume 150-700 0.7 34 1.1 9 12 x 12 VCV/CV-10 V/C Volume 250-1000 0.7 48.6 1.6 11 16 x 12 VCV/CV-12 V/C Volume 350-1500 0.7 72.9 2.4 13 20 x 12 VCV/CV-14 V/C Volume 475-1950 0.7 94.8 3.2 14 24 x 12 VCV/CV-16 V/C Volume 650-2800 0.7 136.1 4.5 16 30 x 12

VCVE/CVE-6 Variable Volume Exhaust 75-400 0.2 - - 12 x 10 12 x 10 VCVE/CVE-8 Variable Volume Exhaust 150-700 0.2 - - 12 x 12 12 x 12 VCVE/CVE-10 Variable Volume Exhaust 250-1000 0.2 - - 16 x 12 16 x 12 VCVE/CVE-12 Variable Volume Exhaust 350-1500 0.2 - - 20 x 12 20 x 12 VCVE/CVE-14 Variable Volume Exhaust 475-1950 0.2 - - 24 x 12 24 x 12 VCVE/CVE-16 Variable Volume Exhaust 650-2300 0.2 - - 30 x 12 30 x 12

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Double Effect Steam Absorption Chiller Schedule Steam Performance Max. Chilled Water Data Absorber-Cond. Water Data Electrical Mark Nom.

Tons Press. psig

Lbs. Ton-hr

Lbs hr Total

GPM ∆P max. (ft. H20)

EWT °F

LWT °F


EWT °F

LWT °F

Volts Max kW

CH-2 800 114 9.69 7754 1280 8.4 59 44 3510 30 85 95 480 11.4

Centrifugal Chiller Schedule (High Efficiency)

Compressor Data Evaporator (Water) Condensor Electrical Unit No.

Nom. Tons FLA kW

Rating kW/ Ton max


EWT °F

LWT °F


EWT °F

LWT °F

Volts Max Amp

CH-1 600 492 333 0.55 960 19.3 59 44 1800 12.0 85 95 480 1000

Cooling Tower Schedule Motor Data Unit

No. Nom. tons

No. of Cells

EWT °F

LWT °F

EAT Wb °F GPM No. of

Fans HP RPM Volts Phase Hz CT-1 1774 2 95 85 78 5320 2 60/Cell 1800 480 3 60 CT-2 50 1 95 85 78 150 1 7.5 1800 480 3 60

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Water Pump Schedule Unit No.

Service Type GPM Head ft. H20

HP RPM Volts Phase Hz Emergency Power

HWP-1 Radiation End Suction 300 65 10 1750 480 3 60 Yes HWP-2 Reheat End Suction 500 65 15 1750 480 3 60 No HWP-3 Shared Standby End Suction 500 65 15 1750 480 3 60 Yes CHP-1 Pri. Chilled Water Double Suction 960 55 20 1750 480 3 60 No CHP-3 Shared Standby Double Suction 1280 40 20 1750 480 3 60 No

SCHP-1 Secondary Chilled Water Double Suction 2240 80 60 1750 480 3 60 No SCHP-2 Secondary Chilled Water Double Suction 2240 80 60 1750 480 3 60 No HRP-1 Heat Recovery Double Suction 1800 80 50 1750 480 3 60 No

PCWP-1 Process Cond. Water End Suction 150 80 5 1750 480 3 60 No PCWP-2 Process Cond. Water End Suction 150 80 5 1750 480 3 60 No CWP-1 Condenser Water Double Suction 1800 80 50 1750 480 3 60 No CWP-3 Shared Standby Double Suction 3620 90 125 1750 480 3 60 No CP-1 Duplex Condensate Return - 90 - [email protected] 3500 480 3 60 No CP-2 Duplex Condensate Return - 75 - 2@5 3500 480 3 60 No CP-3 Duplex Condensate Return - 9 - 2@1 3500 480 3 60 No CP-4 Duplex Condensate Return - 37 - 2@3 3500 480 3 60 No

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Appendix B: Mechanical System flow Diagrams

reed berinato jaharis center

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