polytron pulsar open path gas detector 4 to 60 … · polytron pulsar open path gas detector 4 to...

DINGD8-460 issue 1.0

POLYTRON PULSAR

OPEN PATH GAS DETECTOR 4 TO 60 METRES

COVERPAGE


Section 1-Title Page

Installation and Operation

Of the

POLYTRON PULSAR

Open Path Gas Detector 4 TO 60 METRES

Section 1 Title Page page 2 Section 2 Safety Warning page 3 Section 3 Manual Revision page 4 Section 4 General Diagram page 5 Section 5 Parts Supplied page 6 Section 6 General Description page 7 Section 7 Choosing the path of the Beam page 11 Section 8 Mounting page 12 Section 9. Electrical Connection page 15 Section 10 Installation and operation page 21 Section 11 Planned Maintenance page 38 Section 12 General Specification page 39 Section 13 Certification page 41 Section 14 Part Numbers page 44 Section 15 Fault Finding Guide page 45-49


Section 2-Safety Warning 1 The purpose of the POLYTRON PULSAR is to detect hydrocarbon gases in

quantities that may present an explosion hazard. Thus it is vital for your safety and that of others that its functions are understood and that every aspect of installation, commissioning and maintenance are carried out correctly.

2 This manual is intended to inform you of all aspects of the POLYTRON

PULSAR. However, if you are in any doubt about any part of these instructions, any function of the equipment, or any operating procedure, please contact DRAEGER PLMS LTD. or your local distributor at the address below.

3 The POLYTRON PULSAR is certified and intended for use in potentially

hazardous areas. Install and use the POLYTRON PULSAR in accordance with the latest regulations.

4 Do not drill holes in any housing, as this will invalidate the explosion protection. 5 Maintenance procedures must be carried out in accordance with the relevant work

permit 6 The Polytron Pulsar light sources are eye safe and in addition a visible light filter

has been fitted to the transmitter to minimise the possibility of distracting personnel working near the detector.


Section-3 POLYTRON PULSAR Manual Revision

1 Every effort has been made to ensure that the information contained in this manual is complete and accurate, however DRAEGER PLMS LTD. can assume no responsibility for any errors or omissions contained or their consequences.

2 Should you discover any errors or omissions in this manual, or have

recommendations on how it may be improved DRAEGER PLMS LTD. would like to be informed. DRAEGER PLMS LTD. has included this page so that you can communicate any revisions you feel are necessary. Please photocopy, fill out and return to the address below.

To: Product Support DRAEGER PLMS LTD. LTD 87, St Modwen Road Plymouth Devon PL6 8LH Tel +44 (0) 1752 261777 Fax +44 (0) 1752 261333 Email [email protected]

From Address Tel Fax Email

I suggest the following changes to section/page/para…


Section 4 Figure 1-General Diagram

DRAW

ING

NO

- G

D8 5

7TI

TLE

- Sys

tem

Ove

rview

(4 -

60m

vers

ion)

PRO

DUCT

- GD8

ISSU

E NO

- 1.2

01/

11/0

0

Not f

or m

anuf

actu

reRE

VISE

D BY

-CH

ECKE

D BY

-CH

ECKE

D BY

-DA

TE-

DATE

-DR

AWN

BY -

Paul

Mar

sh

CPr

ecisi

on L

ight

Mea

sure

men

t Sys

tem

s Lt

d.Pl

ymou

th, U

K


Section 5-Parts Supplied

1 The POLYTRON PULSAR detector comes in two parts a Transmitter and a

Receiver. These are supplied ready assembled to their back plates along with their associated Terminal Boxes.

2 An Optical Attenuator for use on beam paths between 4 and 16 metres. 3 A copy of this manual and a quick start guide are also supplied with the detector. 4 You will also require a Commissioning Kit which is ordered separately and

includes; • Hand Held Communicator • 4mm Hexagonal Ball Driver • Test Sheets

5 Optional extras that are not required for operation but are recommended include U

bolts for pipe mounting and lens cleaning solution. See Section 14 for part numbers.


Section 6-General Description of Operation

UNDERSTANDING THE SYSTEM General The Polytron PULSAR detects hazardous releases of flammable hydrocarbons, to established measurement methods, adding new and unique features that overcome common problems encountered in practical installations. A Transmitter sends a beam of light through the air to a Receiver where it is divided and enters two independent measurement channels; one for gas indication, the other for reference. The presence of hydrocarbon gases anywhere along this beam is detected because they absorb particular infrared wavelengths. Rain or snow in the air and dirt on the lenses cannot normally cause a false indication of gas because they do not share these characteristic wavelengths. To these well-proven techniques of open path gas detection, the Polytron PULSAR adds new capabilities:

1. The light is produced by pulsed sources providing a peak power of 30kW. Designed to work with this high Transmitter power, the Receiver is made immune from solar radiation and resonance effects associated with the vibration from rotating machinery. The built-in redundancy of sources ensures that, even in the event of a source failure, the system remains fully functioning until the Transmitter can be exchanged during planned maintenance.

2. A communication path is provided for digital signals going from the Receiver

back to the Transmitter. By this means the Receiver is able to command the Transmitter to double its power (to 60kW) and to increase the flash rate from 1Hz to 4Hz, so providing an eight-fold increase in light flux when visibility is reduced by fog etc. The higher flash rate is also triggered by the first indication of gas, allowing a fully validated gas reading to be output within a much reduced response time.

3. The performance of all open path instruments depends critically on the

accurate aiming of the Transmitter and Receiver towards each other. Often the necessary detection paths require the units to be sited at elevated and inaccessible positions. This can make correct alignment difficult to achieve at the time of installation, and difficult to check at subsequent times when the supporting structure may have moved. For the first time internal sensors are provided to measure the orientation of the Transmitter with respect to the Receiver, and vice versa. Besides being presented graphically on a hand-held Communicator to make installation simple, the directional measurements are available remotely during normal operation, allowing the correct alignment to be checked at will. An automatic pre-warning signal is also generated if the alignment changes significantly, or if an attempt is made to commission a detector that is not correctly aligned.


4. Installations of several open path instruments can suffer interference if a receiver ‘sees’ another transmitter as well as the intended one. The Polytron Pulsar can be switched to eight separate frequencies (Channels 0 to 7) with millihertz separations. Each receiver locks onto the light from its own transmitter and ignores light from its neighbours.

5. The Receiver contains an internal data-logger with a non-volatile memory that

can be read remotely. A detailed record is maintained for the previous 7 days of operation, with consolidated records for the previous 32 weeks. These logs include such essential information as supply voltage, internal temperature, signal strength and Transmitter and Receiver alignment. They provide an invaluable aid to diagnosing practical problems, maximising availability, and preventing unnecessary maintenance work. Internally the information is used to provide an automatic pre-warning if the lenses will require cleaning which is not dependent on temporary weather conditions but based on a long-term comparison of the signal strength against that stored when the detector was last cleaned and re-zeroed.

In addition to these electronic enhancements, the POLYTRON PULSAR has a new mechanical design that provides exceptional stability and ease of adjustment. The head units containing the optical components are each mounted in lockable gimbals that allow separate vertical and horizontal adjustments with the other axis clamped. Each axis can be adjusted with a controlled degree of friction provided by PTFE rings then locked solid without disturbing the setting. An important part of the design is a cover made of marine grade stainless steel. Besides providing mechanical protection, the cover reflects solar and flare radiation and minimises the temperature rise of the head units. Hazardous Area Protection The Polytron PULSAR uses a combination of explosion protection concepts for the Transmitter and Receiver. In each case the head unit is a Flameproof (EEx d) enclosure. An integral cable from the head unit provides power and signal connections to the rest of the system, via an Increased Safety (EEx e) terminal box mounted on the same base plate. Also integral with the head unit is a connector with a waterproof screw cover that provides the Intrinsically Safe (EEx i), optically isolated interface to the hand-held Communicator. For regions where the Increased Safety concept is not in use the terminal box is replaced by a Flameproof (explosion proof) type. Transmitter The Transmitter is a three-wire device, with cabled connections for (i) 24Vdc power; (ii) the digital signals from the Receiver; and (iii) power and signal common. The independent digital port on the head unit allows the Receiver data to be read and displayed on the hand-held Communicator. This simplifies one-man installation, because information about alignment and received signal strength are available at both ends of the system. The Communicator can also access data held within the Transmitter itself, for instance factory-set information such as Serial-number and firmware revision number, and a user-configurable tag reference.


The optical output from the Transmitter is through an electrically heated lens and is mainly infrared. A controlled amount of deep red light is visible if you are close to the lens, or looking along the axis from a distance. Four operating modes can be distinguished visually when the detector is being installed and tested: 1. Normal Mode. Flashes of normal intensity are output once a second. The flash

rate appears regular to the eye, although it is phase-coded to send directional information to the Receiver. Occasionally a flash will be seen out of the normal sequence as part of an internal self-test cycle.

2. Strong Mode. Flashes of increased intensity are output at a regular 4Hz rate. 3. Alignment Mode. Flashes of normal intensity are output four times a second. It is

easily distinguishable from Strong Mode because there is a noticeable irregularity to the flash rate as it sends directional information to the Receiver.

4. Low-supply Mode. Flashes of increased intensity are output at a regular 2Hz rate.

This is substituted for Alignment Mode if the Transmitter detects that the supply voltage dips below the specified range when tested with the lens heater on. This test is only carried out during alignment (and hence at the time of commissioning the detector) so that it cannot delay a gas alarm if this coincides with a deteriorating supply.

A fifth mode is not visually distinguishable from Normal Mode but is used to generate warning signals from the Receiver: 5. Fault Mode. Flashes of maximum intensity are output at a regular 1Hz rate. This

is substituted for Normal Mode if the Transmitter has detected that a tube has failed or is intermittent.

For operating distances below 16m the Transmitter lens is covered by an Attenuator Plate to reduce the light intensity. A central section in the plate is removed for distances between 8 and 16m, retained for distances between 4 and 8m. Receiver The Receiver is a four-wire device, with cabled connections for (i) 24Vdc power; (ii) 0-20mA analogue signal; (iii) digital input/output; and (iv) power and signal common. The analogue output, a current source not requiring an external energising voltage, provides fully linearised 4-20mA gas readings and configurable warning signals below 4mA. The digital line supplies the signals to switch the Transmitter mode and can optionally be routed to the Non-hazardous Area to provide comprehensive digital information on gas reading, signal strength, Transmitter and Receiver alignment, etc. As well as this stream of measured data, which is output at a rate determined by the Transmitter flash rate, the Receiver can also be remotely commanded to output details of its configuration (including a user-configurable tag reference) and the contents of its internal data logger. The same digital connection allows the Receiver to be reconfigured remotely and to have its internal firmware updated.


The independent digital port on the head unit allows the Receiver data to be read and displayed on the hand-held Communicator. Again this simplifies one-man installation, because the alignment and signal strength displays are available in the place they are needed. In general all the facilities provided by the remote digital line are also available via the local Communicator port, but will normally be accessed more conveniently in the Non-hazardous area when the installation allows it. Gas Calibration and Zeroing Like the Draeger PLMS GD4000-series gas detectors, the POLYTRON PULSAR is sensitive to a wide range of gaseous hydrocarbons, including the alkane series from methane to hexane. In contrast to instruments working at 3.4µm, the difference in response to different alkanes is relatively small, of the order of ±50%. The Receiver has provision for factory-installed linearisation tables for up to four specified gases or gas mixtures, the choice of which table is used being configurable by the user. For most applications a Methane table should be selected for mixtures that are predominantly methane, a Propane table otherwise. Each table covers the range 0 to 8LEL.m and the full range of measurement is always available in the digital data stream. The portion of this measurement range that is mapped onto the 4 to 20mA span can be configured freely between 0-4LEL.m and 0-8LEL.m by the user. Note that a choice other than 0-8LEL.m necessarily results in the portion of the measurement range that lies between the chosen full scale and 8LEL.m being clamped at the 20mA reading. The plastic test sheets supplied as part of the Installation Kit provide a convenient operational check, and can be used to confirm that the response has not changed from a reading previously recorded. They are not used for calibration, which is unnecessary, nor do they equate to a particular quantity of gas. Unlike conventional detectors, the built-in calibration of the POLYTRON PULSAR needs no manual adjustment, but a self-zeroing sequence is initiated by the hand-held Communicator to complete the commissioning of the detector. The sequence includes checks that both the Transmitter and the Receiver are correctly aligned and that the Attenuator Plate is fitted when required. Also included is a measurement of the signal strength, used subsequently to determine the loss of signal due to dirt on the lenses. For this reason the zeroing should be carried out in clear conditions, at moderate temperature, and without the beam being interrupted during the minute or so the sequence takes. Until the zeroing has been completed correctly a new detector reads full scale and is not useable. It should also be re-zeroed whenever it is re-sited, cleaned or re-aligned.


Section-7 Choosing the Path Of the Beam

1. The siting of an open path gas detector is often not as critical as a point detector, since the released gas only has to find its way into any portion of the beam instead of to a particular point. However siting is still an important consideration. Guidelines for siting are contained in BS6959.

2. The density of the gas to be detected has to be considered. Methane is lighter

than air and may be expected to rise, unless released at a low temperature or in a mixture with a heavier gas like carbon dioxide. Likewise heavier hydrocarbons may be expected to fall. However such simple considerations as buoyancy may not be a reliable indicator of gas movement in practical situations. Gas leaking from high-pressure systems entrains with it a much larger volume of ambient air, forming a mixture that may be flammable and almost neutrally buoyant. In these circumstances it is the natural air currents or forced ventilation that control the motion of the plume or cloud. Where air movements are unpredictable it may be necessary to use separate beam paths to cover different possibilities.

3. The distance between the Transmitter and Receiver should be between 4 and

60 metres. Note that the Optical Attenuator should be fitted below 16 metres (see section 10) and that the 30-120 metre Polytron Pulsar Transmitter should be employed for beam paths in excess of 60 metres. (See separate manual).

4. The beam path and immediate surround should be kept free of obstructions

that might hinder the free movement of air in the protected area or block the infrared beam. A clear path of 25cm diameter or greater is recommended. For maximum availability it is also recommended to avoid the following-

a. Smoke stacks, chimneys and exhausts. b. Steam vents and plumes. c. Walkways and areas where personnel muster or collect. d. Splash and spray from moving equipment and cooling towers etc. e. Parking, loading, cranes, vehicle temporary stops. f. Vegetation that may grow tall enough to impinge on the path especially

with movement by the wind. g. Surfaces that may obstruct the beam path with a build up of ice or

snow.


Section 8 Mounting

1. The POLYTRON PULSAR should be mounted via its back plate to a stable structure free of excessive vibration. Good choices would be a steel bulkhead, brick wall, concrete lamppost or a rigid steel structure. Avoid flimsy metal structures that may flex, or wooden structures that may warp. In open areas a suitable structure close to the ground would consist of a five inch nominal (141mm outside diameter) steel pipe driven 1 metre into firm ground or embedded into a concrete foundation. Tall structures should be suitably guyed or braced.

2. U bolts are available as accessories for four inch nominal (114mm

diameter) to five inch nominal (141mm diameter) pipes, (see section 14).

3. The POLYTRON PULSAR detector is immune to sunlight so there is

no need to take account of sun position when siting detectors.

4. The POLYTRON PULSAR is supplied orientated on its back plate so that units will face each other when sited on a common wall. If it is required to fit units to opposing walls it is a simple matter to refit the unit, brackets and Terminal Box to the opposite side of the back plate.

5. Due to the assisted alignment system employed by the POLYTRON

PULSAR there is no requirement for a telescope alignment aid. As long as the units are mounted so that they can be approximately pointed at each other the Hand Held Communicator will guide the installer to the correct aligned position.


Figure 2 POLYTRON PULSAR Pole Mounting Arrangements


Figure3 Transmitter / Receiver Wall Mounting

Drae

ger P

LMS

Ltd.

Plym

outh

UK


Section 9 Electrical Connections

There are three options for wiring the POLYTRON PULSAR detector. 1 Via the Transmitter- In this option the cable carrying the power supply and

returning the signal to the marshalling cabinet are routed directly to the Transmitter. A field cable is then required between the Transmitter and the Receiver. This carries the power supply for the Receiver, the 0-20mA output signal and the internal digital signal. (See Fig. 4)

2 Via the Receiver- In this option the cable carrying the power supply and returning

the signal to the marshalling cabinet are routed directly to the Receiver. A field cable is then required between the Transmitter and Receiver; this carries the 24v dc power supply and the internal digital signal across to the Transmitter. (See Fig. 5)

3 From the Marshalling/Control Cabinet- In this option cables are run to both the

Transmitter and the Receiver and the link for the digital information is made in the marshalling/control cabinet/. (See Fig. 6)

Field Cable Specification. -The cables are required to supply between 18 and 27v dc at a peak current of 1.5A peak (all lamps and heaters on). The field cable runs must comply with local regulations. Please refer to Table 1 and 2 below for maximum recommended power cable lengths.


Pulsar Maximum Permissible Power Cable Lengths The following tables give the maximum cable lengths for differing worst case power supply voltages and core sizes. In using this information please note that the worst-case (lowest possible) supply voltage should be used not the nominal stated. The lengths stated are determined by the power supply cores. If cable size and distance become excessive it may be more economic to install a local power supply. There is no practical limit on the distance for the signal cables, although the 4-20mA loop resistance is limited to 500Ω total. Table 1 Maximum Permitted Pulsar Cable Run in Metres Wiring Drawing GD8-58/9 (Figure 4/5) GD8-64 (Figure 6) Common to TX and RX Individual to TX or Rx Worst-case supply 20V 22V 24V 26V 20V 22V 24V 26V

1mm2 50 83 117 150 100 167 233 300

1.5mm2 75 125 175 225 150 250 350 450 2.5mm2 125 208 292 375 250 417 583 750

4mm2 200 333 467 600 400 667 933 1200

18 AWG 41 69 96 123 82 137 192 247 17 AWG 52 87 121 156 104 173 242 311 16 AWG 65 109 153 196 131 218 305 393 15 AWG 83 138 193 248 165 275 385 495 14 AWG 104 173 243 312 208 347 486 624 13 AWG 131 219 306 394 262 437 612 787 12 AWG 165 276 386 496 331 551 772 993 11 AWG 209 348 487 626 417 695 974 1252 10AWG 263 439 614 789 526 877 1228 1578


Table 2 Maximum Permitted Pulsar Cable Runs In Feet Wiring Drawing GD8-58/9 (Figure 4/5) GD8-64 (Figure 6) Common to TX and RX Individual to TX or Rx Worst-case supply 20V 22V 24V 26V 20V 22V 24V 26V

1mm2 164 273 383 492 328 547 765 984

1.5mm2 246 410 574 738 492 820 1148 1476 2.5mm2 410 684 957 1231 820 1367 1914 2461

4mm2 656 1094 1531 1969 1312 2187 3062 3937

18 AWG 135 225 315 405 270 450 630 810 17 AWG 170 284 397 511 341 568 795 1022 16 AWG 215 358 501 644 429 716 1002 1288 15 AWG 271 451 632 812 541 902 1263 1624 14 AWG 341 569 797 1024 683 1138 1593 2048 13 AWG 431 718 1005 1292 861 1435 2009 2583 12 AWG 543 905 1267 1629 1086 1809 2533 3257 11 AWG 685 1141 1598 2054 1369 2282 3194 4107 10AWG 863 1439 2015 2590 1726 2877 4028 5179


Figure 4 Option 1 Powered via Transmitter

1

1

2

2

3

3

4

4

5

5

6

6

7

7

S

S

E

E

1

1

2

2

3

3

4

4

5

5

6

6

7

7

S

S

E

E

DRAW

ING

NO -

GD8

58TI

TLE

- Con

nect

ion

Diag

ram

(OPT

ION

1 - p

ower

ed v

ia Tr

ansm

itter )

PROD

UCT-

GD8

ISSU

E NO

- 1.2

05/

10/0

0

Not f

or m

anuf

actu

reRE

VISE

D BY

-CH

ECKE

D BY

-CH

ECKE

D BY

-DA

TE-

DATE

-DR

AWN

BY -

Paul

Mar

sh

CPr

ecisi

on L

ight

Mea

sure

men

t Sys

tem

s Lt

d.Pl

ymou

th, U

K


Figure 5 Option 2 Powered via Receiver

1

1

2

2

3

3

4

4

5

5

6

6

7

7

S

S

E

E

1

1

2

2

3

3

4

4

5

5

6

6

7

7

S

S

E

E

DRAW

ING

NO -

GD8

59TI

TLE

- Con

nect

ion

Diag

ram

(OPT

ION

2 - p

ower

ed v

ia Re

ceive

r )PR

ODUC

T- G

D8IS

SUE

NO- 1

.2

0

5/10

/00

Not f

or m

anuf

actu

reRE

VISE

D BY

-CH

ECKE

D BY

-CH

ECKE

D BY

-DA

TE-

DATE

-DR

AWN

BY -

Paul

Mar

sh

CPr

ecisi

on L

ight

Mea

sure

men

t Sys

tem

s Lt

d.Pl

ymou

th, U

K


Figure 6 Option 3 Linked in the Control/Marshalling Cabinet

1

1

2

2

3

3

4

4

5

5

6

6

7

7

S

S

E

E

1

1

2

2

3

3

4

4

5

5

6

6

7

7

S

S

E

E

DRAW

ING

NO -

GD8

64TI

TLE

- Con

nect

ion

Diag

ram

(OPT

ION

3 - T

rans

mitt

er a

nd R

ecei

ver p

ower

ed in

divid

ually

)PR

ODUC

T- G

D8IS

SUE

NO- 1

.0

0

8/03

/00

Not f

or m

anuf

actu

reRE

VISE

D BY

-CH

ECKE

D BY

-CH

ECKE

D BY

-DA

TE-

DATE

-DR

AWN

BY -

Paul

Mar

sh

CPr

ecisi

on L

ight

Mea

sure

men

t Sys

tem

s Lt

d.Pl

ymou

th, U

K


Section 10 Installing and Operating the POLYTRON PULSAR Warning During the alignment and zeroing procedure the output from the POLYTRON PULSAR will vary between 0 and 20mA.It is normal to test the POLYTRON PULSAR against Gas Test Cards on completion of the alignment procedure and is therefore important that all control functions are inhibited

1. In order to install the POLYTRON PULSAR the following equipment is required-

a. POLYTRON PULSAR Transmitter and Receiver correctly orientated on the back plate. (Supplied)

b. Hand Held Communicator (Part of alignment kit). c. 4mm Hexagonal Ball Driver (Part of alignment kit) d. Suitable spanner for fixing back plate and fixings. (Not supplied) e. Set of test filters. (Part of alignment kit) f. U bolts if fixing to a pipe. (Supplied if ordered as an accessory) g. Nominal 24v(18-27) dc. h. 3 M20 Ex e certified cable glands if unit is to be powered via

Transmitter or via Receiver. 2 M20 cable glands if unit is to be linked in marshalling/control cabinet. (Not Supplied).

i. Attenuator plate if operating distance is below 16m

2. Carefully unpack the equipment and check the contents of the boxes against the packing note. In case of shortages or damage contact the carrier, DRAEGER PLMS LTD. or the distributor immediately.

3. Mount the POLYTRON PULSAR on a suitable structure as described in

section 8. Ensuring that the beam path meets the criteria laid down in section 7.

4. Connect the field cables (see figures 4, 5 and 6) and apply the power

5. If the beam path is less than 16m the AP800 attenuator must be fitted to

the TRANSMITTER. The attenuator has push out sections depending on the distance over which the POLYTRON PULSAR is to be used. Figure 7 shows the attenuator and the sections which need to be removed depending on the range. To fit the attenuator press the three serrated tabs firmly into recesses in the transmitter lens retaining ring. The POLYTRON PULSAR will not zero if the attenuator is not fitted at ranges under 16m.

6. Now carefully follow the instructions contained in the following pages.


Figure 7 Drawing of AP800 Attenuator Plate

DRAW

ING

NO- G

D8 3

2TI

TLE-

PR

ODUC

T- G

D8

Proj

ectio

nRE

VISE

D BY

-CH

ECKE

D BY

-CH

ECKE

D BY

-DA

TE-

DATE

-DR

AWN

BY- K

eith

Chi

ttyTh

e AP

800

Atte

nuat

or P

late

ISSU

E NO

- 1.0

27/

03/2

000

Fit a

ttenu

ator

to T

rans

mitt

erwh

en le

ns-to

-lens

dist

ance

is 4

to 1

6m

Rem

ove

cent

re fo

r 8 to

16m

Reta

in c

entre

for 4

to 8

m

PLM

SAP

800

Not f

or M

anuf

actu

re

CPr

ecisi

on L

ight M

easu

rem

ent S

yste

ms

Ltd.

Plym

outh

, UK


Pulsar software for the MTL611B hand-held communicator (Software version 1.0 onwards)

Overview The Pulsar hand-held Communicator is used to align the Pulsar gas detector in the field. It is also used to display readings directly in the field and to display a series of warning flags for the purpose of trouble-shooting. A number of other utilities are provided in the software to act as commissioning aids. These utilities allow the user to: • Configure a detector to one of eight different channels to prevent any interference

between detectors when multiple detectors are commissioned in close proximity. • Add an identifying “tag” (11 alpha-numeric characters) to the Transmitter and

Receiver. • Force the output current to a user defined level for systems testing. • Alter the Pulsar’s configuration either manually or by means of a DataPak

supplied by PLMS. • Update the Pulsar’s internal software via a PLMS supplied DataPak. • Download the internally stored data log of the Pulsar’s past performance for

diagnostic purposes. Starting the Pulsar Software on the MTL611 Make sure the DataPak containing the Pulsar software is plugged into the top socket on the communicator. Press “ON/CLEAR” and the software will load automatically. If for some reason this is not the case (e.g. wrong key presses etc.) pressing the ON/CLEAR key for a second time from the main MTL menu will run the software. Running the Pulsar Software on the MTL611 The software is menu driven and each menu can be navigated using the arrow keys. Menu options can be selected by highlighting (flashing cursor on item to be selected) and pressing "EXE" or by typing the initial letter of the required option. To exit from program screens press "SPACE".


Trouble-shooting: In case of problems with the software or the Communicator locking up - repeatedly pressing “ON/CLEAR” or “ON/CLEAR” followed by ”Q” should get you back to the Main Menu. If all else fails, remove the battery, put it back in and press “ON/CLEAR” to re-run the software. Error messages: “Time-out” The communicator works by sending data to the detector through a common data line. It looks for a gap in the traffic and then attempts to send data. If it fails it will try again for a set number of tries. Very occasionally it will get through all these tries without succeeding and the message “Time-out” appears momentarily on the screen. If this happens simply try the function again. One exception to this is when a command directed at the Transmitter has accidentally been sent to the Receiver (or vice-versa). In this case simply plug the communicator into the correct end of the detector. “Not Receiving Data” If for some reason the detector is not functioning normally a message can appear saying “NOT RECEIVING DATA – Check Warning flags”. Selecting “Warning Flags” from the Readings Menu should give an indication of the problem. “Data varying” This message means that several attempts have been made to confirm data by comparing two subsequent readings but that the data is fluctuating. Simply try the function again. Failure to boot software If the battery is getting low error messages can sometimes occur when trying to boot the software even though the low battery warning has not appeared. If this happens replace the battery.


MAIN MENU – ALIGNMENT MENU Alignment and Zeroing procedure for Recommended Configurations (see manual diagrams) IMPORTANT NOTE: If the distance between the Transmitter and Receiver is less than 16 metres an Attenuator Plate should be fitted to the Transmitter. For 4 to 8 metres the centre section should be in place, for 8 to 16 metres the centre section should be removed. TIPS: The alignment and zeroing are best done in good weather conditions, when the temperature is moderate and there is no fog or heavy precipitation. Begin with Transmitter and Receiver pointing towards each other as accurately as possible by eye. This will save time by reducing the number of steps needed for the instrument-aided alignment, and ensure that it homes in on the strong central peak. Be aware that weaker, false peaks can occur when the Transmitter and/or Receiver point away from the correct axis, for instance when light from the Transmitter reflects off an adjacent surface. Adjust the Transmitter or the Receiver with slow, deliberate movements to ensure that the readings are valid and to avoid overshooting the correct position (the alignment readings only update four times a second and up to four flashes are needed for a stable reading). NOTE: the alignment target displays are deliberately more sensitive towards the centre. Use the readout of the horizontal and vertical positions to correct whichever is the larger misalignment shown. Be aware that a large horizontal misalignment can cause the vertical position to read incorrectly, and vice versa. Step 1 – Putting the Pulsar into Alignment Mode Loosen the three screws holding the cover and remove it to gain access to the Receiver head. Unscrew the waterproof cap from the Communications Port and connect the MTL611 Hand-held Communicator. Turn the Communicator on (press ON/CLEAR) and from the MAIN MENU select “Alignment menu” then “Alignment Mode”. A message displays to confirm this Mode. Press “SPACE” to continue.


Step 2 – Initial alignment of the Receiver Loosen the eight clamping screws on the gimbals assembly. Retighten them sufficiently that the head will move smoothly in all directions but remain in position. Select “View alignment data” from the Alignment Menu and the following display will appear (refer to Appendix A) – Observe the Signal level and the Receiver Target (highlighted above) on the display. Adjust the Receiver in the horizontal and vertical directions alternately, each time correcting the one which is furthest from the centre. This should also peak the signal strength (note the numerical display as the bar graph will only appear when the signal is within the range expected for normal operation). NOTE: The peak may remain small at this stage if the Transmitter is not pointing accurately enough towards the Receiver. At the centred position, tighten the eight screws. Do it progressively in rotation to avoid losing the alignment. Remove the Communicator and temporarily replace the watertight cap. The Communicator may now be turned off to conserve battery power. Press SPACE to return to the Alignment Menu, select “Home” for the Main Menu and then “Off”. Step 3 – Alignment of the Transmitter Loosen the three screws holding the cover and remove it to gain access to the Transmitter head. Unscrew the waterproof cap from the Communications Port and connect the Communicator. Press the ON/CLEAR key to re-activate the Communicator and from the Main Menu select “Alignment Menu” followed by “View alignment data”.

S I G * * * M A X * * *

R T


Observe the Signal level and the Transmitter Target (highlighted above) on the display. Loosen the eight clamping screws on the gimbals assembly. Retighten them sufficiently that the head will move smoothly in all directions but remain in position. First move the Transmitter head around to ensure that you have identified the strong central peak and not a weaker false peak. Adjust the head in the horizontal and vertical directions alternately, each time correcting whichever is furthest from the centre. This will also peak the signal strength. Centre the dots on the Transmitter target until the “Aligned” symbol appears (refer to Appendix A). Ignore any variation that movement of the Transmitter causes in the Receiver display. When centred, tighten the eight screws. Do this progressively in rotation to avoid losing the alignment. Remove the Communicator and replace both the watertight cap on the Communications Port and the main cover over the Transmitter. The Communicator may now be turned off to conserve the battery by pressing SPACE to return to the Alignment Menu, selecting “Home” followed by “Off”. Step 4 – Final alignment of the Receiver Connect the Communicator to the Communications Port on the Receiver. Press the ON/CLEAR key to reactivate the Communicator and from the Main Menu select “Alignment Menu” followed by “View alignment data”.

S I G * * * M A X * * *

R T

S I G * * * M A X * * *

R T


Observe the Receiver Target on the display (see above). Make any final adjustment needed to ensure that the dots are central and the “Aligned” symbol is showing (refer to appendix A). Both the Transmitter and Receiver displays should now show correct alignment. If not, repeat steps 3 and 4 until the Pulsar is correctly aligned. NOTE: If either of the targets is more than one division from the centre the Pulsar will not zero. Press SPACE to return to the Alignment Menu. Step 5 – Carry out the Zeroing Sequence. From the Alignment Menu select “Normal Operation” to take the system out of Alignment Mode. A message is displayed to confirm this. Press SPACE. A message appears to say that the unit will now begin the Zeroing Sequence. You are prompted to make sure that there is no gas present in the beam path - this is important to ensure accurate gas readings. Also make sure that no people or objects will obstruct the beam path during the Zeroing Sequence as the signal strength will be recorded as a standard of comparison to detect dirt on the lenses. NOTE: If you are unsure answering “No” will return to the Alignment menu and when the beam path is clear select the Zero option from the menu. If the detector is correctly aligned a bar is displayed which gradually reduces in size to show the progress of the internal Zeroing Sequence. The process is normally completed in about 40 seconds. NOTE: If any of a number of tests is failed the zeroing sequence is halted, the detector returned to Normal Operation and the Warning Flags displayed. Possible reasons for failing to Zero include Transmitter and/or Receiver misalignment, extremes of Receiver temperature and/or supply voltage and obstructions in the beam-path. Another reason is abnormally high signal strength which would indicate that the required Attenuator Plate had not been fitted. If the above occurs sort out the problem and then select Zero from the Alignment Menu to start the zeroing sequence again. When the Zeroing Sequence has been successfully completed the Communicator displays the message “Zero Set” before returning to the Alignment Menu after a few seconds. Turn off the communicator - select “Home” followed by “Off”. Remove the Communicator and replace both the watertight cap on the Communications Port and the main cover over the Receiver. The detector is now fully set up and functioning.


Alignment Procedure Summary – 1. Put detector into Alignment Mode.

2. Initial alignment of the Receiver

3. Alignment of the Transmitter.

4. Final alignment of the Receiver.

5. Carry out the Zeroing Sequence.

Correct operation can be checked with the plastic test cards and the results recorded on the Installation checklist. Once this is completed, remove inhibits as directed by the work permit, local regulations or your safety supervisor.


Additional Options on the Pulsar Software Main Menu MAIN MENU - DATA OUTPUTS Readings Menu Connect the Communicator to the Receiver on a detector which has been aligned and zeroed. Selecting “Current Readings” gives a live display of the current gas reading, signal strength, receiver supply voltage, temperature and software version. There are also graphical displays showing the current alignment state of both Transmitter and Receiver. Press SPACE to return to Main Menu. Selecting “Warning Flags” gives a display of any flags which are being output from the Receiver indicating that user intervention is required. Under normal operation the message “NO FLAGS” is displayed. However if any flags are present they appear as the text labels shown below. Press SPACE to return to Main Menu. The abbreviated Flag labels mean the following - Optics* Optics require cleaning or Attenuator Plate not fitted RxAlign* Receiver is not properly aligned or beam path partially obstructed TxAlign* Transmitter is not properly aligned or beam path partially obstructed TxWarn* Transmitter Fault (e.g. a tube failure) RxTemp Receiver is outside permitted temperature range RxVolt Receiver Power Supply is outside permitted range BeamBlock**Beam-Blocked or otherwise unable to measure Fault** Fault state; for instance BB timeout-to-Fault or a component failure.

* . * * L E L m s i g * * * s / w * *

Recvr: **.*V **degC

T R


*These flags cause the Warning signal (normally 3.5mA but configurable) to be output unless there is a gas reading. **These flags indicate an inability to measure gas. All others are merely warnings that do not prevent measurement of gas. MAIN MENU – READ CONFIGURATION Configuration Menu. If this function is selected you will be prompted to select “Transmitter” or “Receiver”. If “Transmitter” is selected its tag number and channel will be displayed. If “Receiver” is selected you can then select the tag and channel number as above or a readout of the Pulsar’s internal configuration which can then be scrolled through using the arrow keys. Selecting “Home” returns to the Main Menu. NOTE – it may take several seconds before settings are downloaded. Configuration display description Time to BB number of seconds before a beam-block (2mA) is

output. BB to Fault number of minutes before a beam-block output (2mA)

converts to a fault condition (0mA). Gas Calibration No. The current gas calibration table in use (1 - 4) 4-20mA Span The number of LELm indicated by 20mA. AZT Rate The rate at which Auto Zero Tracking will follow drift. Baseline Deadband The level of noise at zero gas reading (4mA) tolerated

before a non-zero gas reading is displayed. Static Warning Sig The current level (mA) displayed when any warning

flag is present. BB to Fault These switches show whether Pulsed Warning o/p each of these functions is Static Warning switched ON or OFF. AZT All these functions may be adjusted using the “Reconfigure” option under the “Utilities” menu. Press SPACE to return to the Main Menu.


MAIN MENU - UTILITIES Force mA output WARNING – This function should not be used when the Pulsar is connected to an active control system. This option allows you to enter a value of between 0 and 20 mA (in integer values) which will appear at the Pulsar output. Presets for beam-block and fault are provided. Tag Change This function prompts you to select whether you are connected to a Transmitter or Receiver, then displays the current Tag (up to 11 alphanumeric characters) and prompts you to enter a new Tag. When this is done the Communicator creates a checksum, sends the new tag to the Pulsar and then confirms it. NOTE – this can take some time. Channel Change Use this function to enter a new channel for the Transmitter or Receiver. Eight channels (0 to 7) are provided for situations where there are multiple Pulsar installations in close proximity to prevent the possibility of interference between detectors. IMPORTANT NOTE Both the Transmitter and Receiver MUST be on the same channel for the Pulsar to operate. Reconfigure NOTE: The Communicator must be connected to the Receiver. This function enables you to change some of the configuration parameters in the Receiver. NOTE: it can take several seconds before the current configuration is read. Once the configuration has been read the “CHANGE CONFIG” menu displays the functions which may be changed. Each of these when selected will display its current state and give you the option to modify it. Once the configuration has been modified to your satisfaction select the menu option “Update config”. The Communicator creates checksums, sends the new configuration to the Pulsar and then confirms it.


NOTE: this process can take time. If you make a mistake or decide not to use the new configuration before it’s sent select the menu option “Quit (do not update)”. Selecting “Home” returns to the Main Menu. Program IMPORTANT WARNING The Pulsar must be disconnected from any control system before this operation is carried out as during reprogramming a Pulsar normal operation is suspended until the reprogramming process has completed successfully. If you have any doubt about the state of the Communicator’s battery replace it before commencing this procedure. This function allows you to update the Pulsar’s internal software. Any new version will be supplied by PLMS in a DataPak which must be inserted into the lower slot in the Communicator. The contents of the DataPak will be displayed and you will be asked if you wish to continue. WARNING: If the answer is “yes” the processor will be erased and the Pulsar will not function again until reprogramming is successfully completed. Uploading the data to the Pulsar will take around 8 to 10 minutes. When uploading is complete a final checksum test will be performed. If this fails for any reason such as interrupted data, the Pulsar will remain non-functional and you will be prompted to try reprogramming again. If the Pulsar programmes correctly a message will be displayed to this effect and the detector can be reconnected to the control system. Download logged data This option provides a means of downloading data held in the Pulsar Receiver’s internal log which stores performance data for the preceding weeks of operation. This can be analysed by PLMS and is useful for trouble-shooting purposes. The data in binary form is downloaded from the receiver into the Communicator’s internal memory where it can be copied to a DataPak (or PC using a suitable serial link) and forwarded to PLMS for analysis. NOTE – it is important that the Communicator’s internal clock / calendar are correct as this is used to time and date stamp the data file. To alter the settings quit the Pulsar software.


Select “Time” from the communicator’s Menu. Press “Mode”and select “Set”. Use the arrow keys to adjust the clock / calendar and press EXE to set and then on/clear to return to the menu. Rerun the Pulsar software by pressing on/clear again. MAIN MENU – ABOUT Displays the Communicator software version MAIN MENU – HELP Provides a brief help file MAIN MENU – OFF Turns off the Communicator MAIN MENU – QUIT PROGRAM Leaves the Pulsar software and returns to the Communicator’s Main Menu


Appendix A Alignment Display

R

Signal Level Bar Graph displays when signal is

within normal range

Transmitter Target Left / Right and Up / Down

positions

Receiver Target Left / Right and Up / Down

positions

Flashes when data is being received

↑↑↑↑

Unit al

Unit slighand

Unit ceanslig

Example Target Displ

S I G * * * M A X * * *

T

Current Signal Level Numerical
Maximumvalue

Values

centrally igned

pointing tly to left too low

ntral left / right d pointing htly high

ays (Transmitter and Receiver)

Unit central up / down and pointing slightly right

Unit pointing slightly down

and too far right


Appendix B - Menu Tree Main Menu Alignment Menu Data outputs Help Read configuration Utilities Version Off Quit

Alignment Menu Alignment mode View alignment data Normal operation Zero detector (tx alignment mode)* Home Readings Menu Current readings Warning flags Home Help General operation Alignment procedure Flags Home Configuration Transmitter Receiver Utilities Menu Force o/p current Tag change Channel change Reconfigure Program Download logged data Home

Configuration Display tag/channel System configuration Change Tag Transmitter Receiver Change Channel Transmitter Receiver Change Config Auto zero track Gas type Span (4-20ma) Beam block delay Timeout bb to fault Static warning Pulsed warning o/p Baseline deadband Load external config Update config Quit (do not update)


*Note Tx alignment mode is included as a commissioning aid only. It enables the transmitter to be placed in alignment mode independently of the receiver.

Installation Checklist

Please complete the installation check sheet and return it to DRAEGER PLMS LTD. so that we may be able to better assist our customers.

PLMS PULSAR INSTALLATION REPORT FORM DateCustomer SiteInstaller Name CompanySystem DetailsPath LengthTarget GasTag No RXTag No TX

TX RX

Successful Zero Y/NTest Cards 1 2 3 4 5General Observations

Serial No TX

Attenuator fitted Y/N

Serial No RX

MountingVibration

Excess HeatVoltageEarthingRFI/EMC

ContaminantsObstructions

Comments

Signal Strength


Section 11 Planned Maintenance

1. The POLYTRON PULSAR has been designed so that it will give long and reliable service with the minimum of maintenance. The POLYTRON PULSAR will warn the operator if the Optics become contaminated or if it becomes misaligned for any reason.

. 2. Depending on the application and the environment as well as the work

practices at the site planned maintenance consists of-

a. Checking the detectors response to Gas Check Cards. Ensuring first that any control functions have been inhibited.

b. Cleaning the optics as necessary. If the detector warns of

contaminated optics or if it is known that the detector may have been contaminated by drilling mud, oil mist, dust etc. The lenses are specially coated to assist in keeping them clean, however if it becomes necessary to clean them care must be taken so as not to remove the lens coating. A soft cloth with clean fresh water or DRAEGER PLMS LTD. lens cleaning fluid should be used. The detector should be realigned and rezeroed as per the instructions following any work on the detector.

Safety Warning The POLYTRON PULSAR Transmitter and Receiver contain no user serviceable components. In the event of suspected failure of the Transmitter or Receiver the suspect unit should be returned to DRAEGER PLMS LTD. IN ANY EVENT NO ATTEMPT SHOULD BE MADE TO DISSASSEMBLE THE UNITS IN THE HAZARDOUS AREA.


Section 12 Specifications

12.1 Materials Housing Electro-polished marine grade stainless steel Mountings/brackets Marine grade stainless steel Cover Marine grade stainless steel Lens Coated optical glass. Integral Cable Armoured, flame retardant, halogen free, mud resistant 12.2 General Range 4 to 60m . Span Configurable between 0 – 4 LEL.m and 0 – 8 LEL.m. Source life Built-in redundancy, signals lamp failure with continued

operation. Calibrations. Receiver holds factory-calibrations for up to 4 gases that can be

selected by factory or field configuration. Gases detected include the alkane series methane to hexane.

Response time Normally ≤3 seconds to ≥90% following a step change in path-

integral concentration. Increases to ≤10s to achieve maximum performance in fog.

Interference Immune to sun, common contaminants, and flare radiation

≤2kW/m2 at ≥30° to optical axis continuous (≤3kW/m2 at ≥30° to optical axis for ≤ 20 minutes)

Alignment Built in directional guidance system.

Zeroing not possible unless correctly aligned (±0.15º or better). Tolerance of ±0.6° before Beam Block.

Mounting Dual clamping pivot assembly. Firmware Programmable via flash memory (for revisions/options) by

remote communications.


Outputs 0-20mA with Fault at 0 mA and blocked beam at 2mA

Pre-warning for dirty or misaligned optics or first lamp failure via pulse and at a static warning level (3.5mA or configurable 0 to 5mA). Local interrogation/diagnostics of the detector via the hand-held device.

Connections Three wire Transmitter, four wire for Receiver (4th wire

optional for digital communication). Power Supply 18 – 27VDC (24VDC nominal). ≤ 2A with heaters on and at

peak of Transmitter charging cycle. Operating Temp. -40 to 60C. Optics Heated to eliminate snow/icing. Dimensions 350 x 300 x 170mm Weight Transmitter 3.5Kg Receiver 3.3Kg


Section 13 Certification

13.1 POLYTRON PULSAR Transmitter and Receiver Note. The Polytron Pulsar is one of the family of Detectors certified under the designation GD8. All certificates will relate to the GD8. International Certification IEC certificate number Sira Ex00Y1176 Ex d[ia] IIC T5 (Tamb = -40°C to +60°C) Ex d[ia] IIC T6 (Tamb = -40°C to +40°C) European Certification ATEX Certificate number SIRA 00ATEX1175 II 2 GD

EEx d[ia] IIC T5 (Tamb -40 to +60°C) EEx d[ia] IIC T6 (Tamb -40 to +40°C)

Ingress Protection (with weatherproof gasket) IP66 Electromagnetic Compatibility EN50270 FCC Part 15 Class A 13.2 Terminal Box Increased Safety Type ATEX Certificate number BASATEX3008X

IIG, EEx e II T6

Material- Glass filled polyester, flame retardant to IEC92.1, UL94V0

Ingress protection- IP66 Anti static- <109 Ohm Impact resistant- >2 x 7 Nm


13.3 Hand Held Communicator European Certification - BASEEFA Data Terminal: Certificate number BASEEFA No. Ex91C2323 EEX ia IIC T4 Tamb 50°C Communications Module: Certificate number BASEEFA No. Ex 91C2071 EEX ia IIC T4 Tamb 50°C USA Certification - FMRC Data Terminal: Intrinsically safe C, I, Groups A-D Non Incendive for Class 1, Division 2, Groups A – D T4 Communications Module: Intrinsically safe Class 1, Division 1, Groups A, B, C, D. T4 Canadian Certification - CSA Data Terminal: Ex ia Class 1, Groups A, B, C, D. Temp. Class T4 Communications Module: Ex ia Class 1, Groups A, B, C, D Temp. Code T4 Australian Certification - SIMTARS Certificate number SIMTARS AUS Ex1375X


13.4 The POLYTRON PULSAR Certification Label Explained ATEX – ATmospherique EXplosif

WARNING - DO NOT OPEN WHEN AN EXPLOSIVE GAS ATMOSPHERE IS PRESENT.THIS APPARATUS MUST BE EARTHED.

READ AND UNDERSTAND INSTRUCTIONS BEFORE OPERATING OR SERVICINGCABLE SUITABLE FOR HIGH TEMPERATURES MAY BE REQUIRED

= 30 VdcU i = 2.4 WP i

OPEN PATH GAS DETECTOR TYPE GD8SERIAL NUMBER 7xxxxx/yy

P L Y M O U T H E N G L A N DDraeger PLMS Ltd.

= 0C i = 0L i

CERTIFICATE no.Sira 00ATEX11750518 II 2 G D

EEx d [ia] IIC T5 (Tamb -40 to 60 C) T6 (Tamb -40 to 40 C)

ManufacturerDetector type unit serial numberyy denotes year of manufacturei.e. 00 = year 2000, 01=2001 etc.

CE markdenotes unit complies withapplicable European directives

Identification no. of ATEXNotified Body (SIRA)

Certification NumberExplosion Protection mark Confirms compliance with ATEX directive.II = Group II equipment (for surface industries)2 = Catagory 2 equipment (high level of protection)G = Certified for gasesD = Certified for dusts

Temperature classUnit surface temperaturewill not exceed T5 (100°C at ambient 60°C)T6 (85°C at ambient 40°C)Certification valid to -40°C

Maximum input voltage

Maximum inputpower

Maximum internalcapacitance

Maximum internalinductanceEEx d [ia] IIC

Apparatus group (gas group)suitable for IIA, IIB, IIC gases (EN50014)

Protection concept of associated apparatus(intrinsic safety)

Protection concept(flameproof enclosure)

Hazardous area equipmentCertified to European (CENELEC) standards

Communications Port intrinsic safety parameters


Section 14 PARTS LIST Part Number Description 2350292 POLYTRON PULSAR Transmitter and

Receiver 4 to 60m CENELEC complete with back plates and Terminal Boxes.

2350292 POLYTRON PULSAR Transmitter and

Receiver 4 to 60m US complete with back plates and Terminal Boxes.

2350296 POLYTRON PULSAR installation kit

comprising, hand held communicator, 4mm hexagon driver and set of test sheets.

2350302 Set of four U-bolt clamps (sufficient to mount

both a Transmitter and a Receiver on a pole). 2350300 Hand held communication terminal 2350211 Set of test sheets 2350305 Hexagonal Ball Driver 4mm 2350306 POLYTRON PULSAR Attenuator 2350291 Lens Cleaning Fluid 2350297 Sun Shield 2350298 Junction Box Pulsar (CENELEC) 2350299 Mounting Plate Pulsar 2350301 Data Pack, Interface and cable for MTL611 (for

customers already in possession of MTL611)


Section 15 Fault Finding Guide The Analogue Current Loop In most installations the first indication of detector condition is the analogue current loop reading. To interpret it fully you need to know what digital configuration has been loaded into the Receiver. Be sure to distinguish clearly between these four conditions: The 4-20mA measurement range. Readings in this range indicate gas on a linearised scale between zero and a full scale quantity of a particular gas. That span and the choice of gas are part of the Receiver configuration. Typically the 20mA reading corresponds to 5 or 8 LEL.m of methane or of propane. The Pre-warning level. This current is output to warn of conditions that could, eventually, cause an inability to detect gas: misalignments of the Transmitter or Receiver, dirty lenses, or mistriggering of a flash tube. Note that the detector retains its full sensitivity and that any gas reading above a low, configurable threshold overrides the warning. Normally the level is 3.5mA and the threshold is 0.5 LEL.m. However, some control equipment cannot resolve currents below 4.0mA so 4.5mA, for instance, may be chosen. There is no ambiguity provided the current chosen corresponds to a gas reading below the threshold. The Beam-block level An output of 2mA shows that the detector is not able to detect gas for reasons other than a hardware fault at the Receiver. They include fog or a solid obstruction in the beam path, or that the Receiver has become misaligned by two to three times the amount that initiates the Pre-warning. For compatibility with other Draeger PLMS equipment the 2mA current is fixed, but two time intervals associated with it are configurable. The first is the time an obstruction must stay in the beam path to cause a Beam-block, normally 60 seconds. The second is the time a Beam-block must persist to generate a Fault, normally 60 minutes. In installations where beam interruptions are frequent and tolerable it may be this delayed event which prompts action rather than the Beam-block itself. The Fault level. An output below 1mA indicates that the detector requires attention, either because of a persisting Beam-block (see above) or a hardware fault. There may be a fault either in the Receiver itself or in the cables and terminations supplying it. Note that a fault which prevents the Transmitter working at all is not distinguishable from an obstruction in the path, so it will generate Beam-block rather than Fault. Note too that the fault-tolerant design of the Transmitter ensures that a partial malfunction will not stop the detector working correctly. However it does generate the Pre-warning (see above) and inhibit alignment and re-zeroing. Be aware that spurious ‘faults’ may be caused if the Draeger PLMS Polytron Pulsar is used with control equipment from other manufacturers without sufficient attention to


detail. Analogue loops are inherently prone to small drifts. Thus a system programmed to recognise any current outside 4 to 20mA as Fault will do so if a zero gas reading drifts to 3.99mA. Likewise, tolerance bands of say ±0.25mA should be allowed for the Pre-warning and Beam-block signals. Note too that incorrectly chosen control equipment can also cause a problem if it attempts to energise the loop, as if for a loop-powered sensor. The analogue output terminal of the Pulsar is itself a current source, requiring just a passive load or sensing resistor not exceeding 500Ω. Fault finding Once an abnormal condition has been identified from the analogue loop signal, it is most easily investigated by looking at the digital signals. The Hand Held Communicator (HHC) can be connected at the Receiver both to view the data stream and to interrogate the Receiver configuration. At the Transmitter the data stream and the Transmitter’s (less extensive) configuration are available. If the AI500 Digital Interface is installed then its Communicator port in the Safe Area is directly equivalent to the HHC connection at the Receiver. For more comprehensive diagnostic purposes the AI500 also allows the long-term records from the Pulsar’s internal data logger to be downloaded into a portable computer via the infrared Data Wand. Besides measured values and flags as described in Section 10, notice that the HHC shows when new data is received with a block in the top right corner of the Flags display. This useful indicator pulses every few flashes normally, but only a few times a minute if the Receiver is not registering light from the Transmitter. Voltage and current are measured most conveniently at the terminations of the field cables in the Safe Area. Be aware, however, that voltage measurements here will not take account of the volt drops in the field cables. Direct electrical measurements at the Transmitter and Receiver terminals will not normally be possible without a safety (‘hot-work’) permit. Such measurements can be misleading, however, since the current consumption varies continuously with the internal heater and Transmitter charging cycles. Problems relating to the Transmitter Symptoms: The detector outputs Beam-block. The HHC receives data only a few times a minute. The Transmitter is not flashing. Cause: The Transmitter is not powered. Action: Check power supply and cabling. Cause: The Transmitter has an internal fault. Action: Remove the Transmitter head and gimbal assembly from the mounting plate (4 x M8 bolts), replace it with a spare configured to the same Channel, and return it to the factory. Changing the Transmitter will not affect the calibration of the detector, but it must be realigned and re-zeroed in the normal way.


Symptoms: The detector outputs Beam-block. The HHC receives data only a few times a minute. The Transmitter is flashing and there is no obstruction in the path but the Receiver is blind to the flashes. Cause: The Transmitter and Receiver are configured to different Channels. Action: Reconfigure the Transmitter and/or the Receiver so that their Channels are the same. Symptoms: The detector output is at Pre-warning. The HHC indicates a Transmitter Fault. Cause: The Transmitter is in Fault Mode because an internal test has indicated that one or more of the flash tubes failed to trigger. The test is made more stringent than normal operation by attempting to trigger the tube at a reduced voltage. A complete cycle of tests is completed a few times per hour if the flash rate is once per second. Action: It is not essential to replace the Transmitter urgently, because the detector remains operational and its performance is not significantly impaired. The Pre-warning may clear of its own accord. If it persists then the Transmitter should be replaced at the next convenient opportunity. Remove the Transmitter head and gimbal assembly from the mounting plate (4 x M8 bolts), replace it with a spare configured to the same Channel, and return it to the factory. Changing the Transmitter will not affect the calibration of the detector, but it must be realigned and re-zeroed in the normal way. Symptoms: When the detector is switched to Alignment Mode the Transmitter flash rate fails to change to four per second, but remains at once per second. Cause: The link is not connected between the Receiver and the Transmitter. Action: Connect the HHC to the Transmitter. The cause is confirmed if the HHC receives no data. Check the cabling and connections. Cause: The Transmitter is in Fault Mode which prevents the detector being aligned and zeroed. Fault Mode is designed to allow the detector to continue working until it is convenient to gain access to it. However it is not recommended to reinstall a Transmitter already in Fault Mode. Action: Confirm that the HHC indicates Transmitter Fault. Further action as shown above for this Pre-warning. Symptoms: When the detector is switched to Alignment Mode the Transmitter flash rate fails to change to four per second, but instead changes to two per second. The HHC does not show any alignment data. Cause: An internal test in the Transmitter has detected that the supply voltage is too low. The test is more stringent than an external voltmeter test because it is made with the heater switched on and at the peak of the charging cycle. Action: Check the supply voltage at its source and that the cable run does not exceed the maximum specified for the core size used. Symptoms: We have installed several detectors at similar distances. One shows a lower signal strength than the others. Its alignment readings also seem to wander. Cause: A difference of six on the HHC’s signal strength scale (in dB units) corresponds to a halving of the signal strength. Variations of a few dB between units are normal. Larger variations could indicate that a Transmitter or Receiver has been aligned onto a false peak. For instance, the Receiver may see the Transmitter both directly and as a reflection in a shiny surface close to the beam path.


Action: Realign and rezero the detector, taking care to find the strong central peak. In some circumstances a strong reflection could cause false misalignment warnings and need to be screened or covered. Cause: The mountings of the Transmitter and/or Receiver are not sufficiently rigid. Action: Provide additional bracing for the mountings. Notice that their rigidity is more important than their strength, changes in direction more important than translational movements. Problems relating to the Receiver Symptoms: The detector output is at Fault (<1mA). The HHC receives no data. Cause: The Receiver is not powered. Action: Check the power supply and cabling. Cause: The Receiver has an internal fault. Action: Remove the Receiver head and gimbal assembly from the mounting plate (4 x M8 bolts), replace it with a spare with the same configuration, and return it to the factory. Realign and re-zero the detector in the normal way. Symptoms: The detector output is at full scale (20mA). Cause: The self-zeroing sequence has not been completed. Action: Align and zero the detector in the normal way. Symptoms: The detector fails to complete the self-zeroing sequence. The HHC shows the Optics flag is set. Cause: An internal check has detected an abnormally high signal strength. This is normally due to the Attenuator Plate not being fitted. Action: Measure the distance between the Transmitter and the Receiver. The Attenuator Plate must be fitted if the distance is below 16 metres. The central cut-out must be removed if the distance is between 8 and 16 metres. Symptoms: The detector fails to complete the self-zeroing sequence. The HHC shows flags indicating Transmitter and/or Receiver misalignment, even though no flags were set in normal operation. Cause: The tests for correct alignment are made more stringent during the self-zeroing procedure. This is to give the detector the best chance of working reliably, allowing for small movements in the supporting structure over a period of time. Action: Check that both the Transmitter and Receiver are rigidly mounted. Carefully repeat the alignment procedure, ensuring that both the Transmitter and Receiver are aligned at the centre of the strong central peak. Restart the self-zeroing procedure. Symptoms: The detector output is at Pre-warning. The HHC shows the Optics flag is set. Cause: The signal strength has remained for some time significantly below the signal recorded when the detector was last zeroed. The margin of signal loss, and the interval for which it must be maintained, to generate the warning are both part of the Receiver configuration. Typical values are 40% loss for more than four days. Action: Check the lenses of Transmitter and Receiver are clean. If necessary, clean, realign and rezero the detector. In some locations fog may persist for longer than the


chosen interval, causing the warning to be generated. It may then be ignored, or a longer interval entered. Symptoms: The detector behaves erratically. It changes unpredictably from normal operation with the HHC showing a strong signal to a Beam-block and little or no signal although the path is not obstructed. The HHC continues to receive data at the normal rate even when power is removed from the Transmitter. Cause: The Receiver is seeing light from more than one Transmitter on the same Channel. Action: Ensure that Receivers of all detectors within sight of each other are configured to separate Channels, and that each Transmitter is configured to the same Channel as its own Receiver. Symptoms: The detector output is at Beam-block. The HHC shows the ‘RxAlign’ flag is set, even though it was not set before the Beam-block occurred. Cause: The optical tests which detect misalignment of the Receiver also serve to prevent its giving false gas readings due to a partial obstruction of the beam. If a partial obstruction capable of causing a false alarm persists for longer than the Beam-block delay it will cause a Beam-block that is indicated like this. Action: Check for causes of partial obstruction such as a vehicle, a crane or a build-up of snow or ice intruding into the beam path. Cause: The Receiver has become sufficiently misaligned to cause a Beam-block in a time too short for the warning to be generated. Action: Investigate the cause of the movement. The Receiver may have been struck or the supporting structure may not be sufficiently rigid. Symptoms: We have installed several detectors with similar configurations. One shows a lower response to the plastic test sheets than the others. Cause: The inbuilt calibration is for the specified gas, not for solid plastic. The sheets are intended to demonstrate that the detector is working correctly, not to simulate any particular quantity of gas. It is normal for individual units to show widely differing responses to the sheets. Action: If required, the gas response can be tested directly and in situ using the gas cells supplied in the GCK400 kit.

polytron pulsar open path gas detector 4 to 60 … · polytron pulsar open path gas detector 4 to...

Documents