Electronic Refrigerant Gas Detectors

Transcription

1 1.0 Introduction Electronic Refrigerant Gas Detectors Electronic Devices Ltd (EDL) is our preferred supplier for ammonia and type L1 refrigerant detection systems. CBISS and Vaisala are our preferred suppliers for the detection of Carbon Dioxide refrigerant. All alternative suppliers shall be referred to the Technical Department. Details of the EDL systems are given in Appendix A. Details of the MSA Pentagas system are given in Appendix B. Details of the Drager Regard system are given in Appendix C. Details of the CPC system are given in Appendix D. Details of the Vaisala system are given in Appendix E. Details of the CBISS system are given in Appendix F. Note that the provision of an electronic gas detection system does not reduce the need for regular manual leak detection checks. The gas detection system would probably fail to detect even a large loss of gas in a well ventilated plant room. Gas detectors increase safety and warn about the presence of refrigerant at unacceptable levels. Leak detection, which can be with hand held detectors, soap and water, UV lamp and tracer dye, etc, is to find and pinpoint leaks. The installation of the gas detection system should be in accordance with the latest edition of BSEN378 and the manufacturer's installation instructions, using ATEX approved equipment where applicable. 2.0 Alarm Levels Our gas detectors will normally be set as detailed below. Any deviation from these settings shall be referred to the Technical Department. Where specified, a signal can be wired to TELSTAR which can be programmed to report a "Refrigerant Gas Detected" message. 2.1 Type L1 Refrigerant Alarm Concentrations (other than Carbon Dioxide) Low concentration level 500 ppm (0.05%) High concentration level 1000 ppm (0.1%) 2.2 R744 Carbon Dioxide Alarm Concentrations Low concentration level 5000 ppm (0.5%) 2.3 R717 Alarm Concentrations Low concentration level 500 ppm (0.05%) High concentration level ppm (1.0%) Note that refrigerant types are defined in BSEN378:2007. Ammonia is in Safety Group B2. The 500 ppm and 1000 ppm alarm levels for type L1 refrigerants may be reduced to 300 ppm and 800 ppm respectively where we are using gas specific sensors (e.g. like the CBISS sniffer system) where the lower alarm levels are unlikely to give spurious alarms. The 500 ppm and ppm ammonia alarm levels reflect those set by BSEN378 which calls for low concentration level action at not greater than 500 ppm and for high concentration level action at not greater than ppm. On some occasions (for example where the equipment is in an occupied area) we may be asked to provide an alarm at even lower concentrations say 250 ppm (0.025%) or even 50 ppm (0.005%). For these cases it may be possible to substitute this lower concentration alarm level in place of the 500 ppm low concentration level. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 1 of 21

2 The low concentration level alarms are associated with toxic levels. At the low concentration level the mechanical ventilation shall be activated. In addition, we can arrange to give advance warning of a refrigerant gas loss by signalling TELSTAR. At the high concentration level we must isolate all electrical circuits within the plant room except the vent fans. We should include provision to send a signal to switch on emergency lighting etc. This will normally be done from a "ventilation control panel" located outside the plant room. It should be noted that, if an under-voltage trip or a circuit breaker is used to remove power, it should be fed from a battery backed power supply or UPS, otherwise some means of automatically resetting it after a power cut will be necessary. A normally closed contact to enable the alarm to be wired to a security office should also be provided. 2.4 ATEX Equipment The ATEX (ATmospheric EXplosive) directive became mandatory on 1 st July The ammonia sensors, the emergency lighting and the emergency fans shall all be specified to work in an ATEX Zone 2 area and approved to ATEX directive 94/9/EC including an assessment to EN Low Concentration Alarm Level Signal to TELSTAR The TELSTAR transmitter or PLC and HMI with modem connected may be mounted outside the plantroom but shall have its power supply arranged according to Standard Specification 26 section 5.6. The TELSTAR controllers and PLCs in most cases are powered from the live side of the starter panel main isolator. The low concentration level alarm signal is sent to a selected controller or PLC. In the case of ammonia (but not type L1 and R744), there must be some means of maintaining the power feed to the selected controller or PLC for 120 seconds after the high concentration alarm is triggered. This is to allow TELSTAR time to report the gas detector low concentration alarm signal if the alarm level goes straight to high level. This is best achieved by deriving the power supply for this particular controller from the vent control panel via contacts of a "delay on de-energise" electro-mechanical timer because the vent control panel power is not cut off in the event of a gas detection. 2.6 Requests for Lower Concentration Alarm We shall, from time to time, receive requests for detectors to operate on ammonia in the OEL range of concentrations, i.e ppm. These levels can be detected by the same sensor type used to detect the 500 ppm level. 2.7 Gas Detectors In addition to the infra-red detection system (which is dealt with separately), there are three main sensor types which are of interest to us. These are electro-chemical cells, semiconductor type sensors and pellistor (or catalytic) sensors. Toxic gases are normally detected in industrial environments by electro-chemical cells. Semi-conductor and pellistor (or catalytic) sensors are used for flammable gas detection. When ordering sensors and systems for use in ammonia plantrooms we must always state that sensors and systems shall be intrinsically safe and suitable for Zone 2 hazardous areas. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 2 of 21

3 2.7.1 Electro-chemical Cells The 50 ppm and 500 ppm ammonia gas detection alarm concentration requires us to use electro-chemical sensors. These sensors are designed to detect low toxic levels of ammonia. The sensors are essentially small batteries which start to discharge as soon as they are manufactured. The discharge rate is increased when in the presence of the target gas (and in some instances, but to a lesser extent, by other gases). They have a lifetime of perhaps eighteen months to four years (dependent on background gas levels and operational conditions of temperature and humidity). When using electro-chemical cells, it must be accepted that they are consumable items which need replacement at regular intervals and that this may be expensive. When ordering these sensors it is important to ask for delivery just ahead of when they will be needed. Remember, they have a limited lifetime which starts from the time of manufacture Semi-conductor Sensors The 10,000 ppm ammonia gas detection level and all L1 refrigerant gas detection levels can be covered with rugged semi-conductor sensors. The main advantages of semi-conductor sensors are long life, their ability to operate in harsh environments, fast response time and low power consumption. The major disadvantage is their response to other gases, leading in some cases to spurious alarms Pellistor (or Catalytic) Sensors These sensors can also be used to detect the ppm ammonia and all L1 gas detection concentrations. The fundamental principle of the pellistor sensor is that the flammable gas is burnt on the surface of a heated platinum wire coated with a catalyst. Rises in temperature and resistance are detected electrically. However, the sensor head can be poisoned by other compounds and the sensitivity can be markedly reduced if the sensor is immersed in large concentrations of the gas it is supposed to be detecting. Note, a pellistor may not detect if switched on in the presence of a gas with a concentration above the Lower Explosive Limit (LEL). 2.8 Infra Red Detection Systems With this system, a small vacuum pump is used to draw filtered samples from several points and deliver them in sequence to an infrared analyser. The analyser searches the sample for the presence of the specific gas and can identify the zone from which it was taken. The analyser can detect ammonia levels in the range 0 ppm to ppm. 3.0 Power Supply to Ammonia Gas Detection Systems In the case of ammonia engine rooms where, in the event of an ammonia gas detection power is shut off from the plant, an independent supply to the detection system shall be maintained. Battery back-up or a UPS will be used for all ammonia plant gas detectors but this is not mandatory for LI or carbon dioxide plant. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 3 of 21

4 With ammonia plant and where we are using EDL equipment, our preference will be to fit an ED 811 with a UPS and up to four sensors. On larger plants we would fit an ED700 with a Type 3 battery backed power supply. Warning: Type 3 power supplies purchased and fitted prior to January 1998 are not equipped to trickle charge the lead acid battery if the battery is completely flat. If mains power has been off for over 10 hours we must assume the battery is flat. In this case we must remove the battery and charge it up on the bench. Type 3 power supplies purchased after January 1998 are fitted with a current limit device which will power the equipment while simultaneously charging the battery. 4.0 Power Tripping Devices There are two types of tripping devices available to isolate the electrical circuits within the plantroom in the event of an ammonia alarm. These are: (a) (b) a shunt trip (where power is supplied to a switch to effect the power trip) preferred an under voltage trip (where power is removed from a switch to effect the power trip) Figures SS106-01, -02 and 03 show some typical wiring diagrams. 4.1 Shunt Trip A shunt trip does not have to be reset following a power cut. The power to the tripping device control circuit can be taken from the gas detection / ventilation panel. The shunt trip control circuit should have a circuit healthy lamp. In the event of a loss of power to the control circuit, the circuit healthy lamp will not be energised. The shunt trip shall be activated via a true off delay timer. This is to avoid nuisance trips on sites with poor power supply conditions. 4.2 Under voltage Trip Where we fit an undervoltage trip we also fit an Uninterruptable Power Supply (UPS). The UPS will energise an undervoltage trip relay in the compressor control panel and will prevent the control panel from tripping out at a power cut. ED700 systems will have a dedicated smaller UPS for the compressor control panel undervoltage trip circuit. At a high concentration level alarm, the feed to the undervoltage trip relay will be removed to isolate the panel. An override keyswitch will be provided to allow the following during maintenance: the feed to the undervoltage trip relay in the compressor panel will not be removed if a high concentration level occurs and the keyswitch is in the override position. Note, An exception to this rule is the plantroom ammonia break glass alarm. In this case, if the break glass alarm is activated the refrigeration plant will shut down via electro-mechanical interlocks, as for a high concentration alarm. The override key switch will not prevent these actions. the audible alarm will not sound L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 4 of 21

5 5.0 Sensor Placement The number and placement of gas detectors on a job will relate to its size and the amount of machinery specified. A detector can normally cover an area of about 36m 2. Cable runs from the refrigerant detector to the sensors should be made with BICC 3093Y/0.75mm 2 cable and should not exceed about 100m. Where longer cable runs are needed we may need to run different cable. In this case we should get guidance from the gas detection equipment supplier. Priority should be given to positions close to compressor shaft seals and liquid pumps. In general, for Type L1 gases, the sensors should be placed below the machinery. In general, for R717, the sensors should be placed above the machinery, however on pumped ammonia installations one sensor should be placed at low level near the pumps to detect liquid spillage. We may choose to fit several sensors around the engine room, however at least one sensor shall be suitable to detect the low alarm level (at say 500 ppm). Where we are detecting refrigerant levels in an air vent duct we will need to purchase a duct mounting kit and splash guard. Where we are using an infra red detection system the sample gas is drawn into a 6mm OD plastic tube fitted with an end-of-line filter. The plastic tubes are run back to the analyses unit which can be mounted in a non-hazardous area. The vent line from the analyser should be piped back into the engine room. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 5 of 21

6 Appendix A Electronic Devices Limited (EDL) A1.0 Preferred EDL Equipment The EDL refrigeration gas detection system preferred by Star Refrigeration Ltd are as follows: The Electronic Devices Ltd Type ED 811 system which can handle up to 4 sensors. The unit can be used with an Uninterruptible Power Supply (UPS). The Electronic Devices Ltd Type ED 700 system which can handle up to 16 sensors (12 if internal zener barriers are required, e.g. on R717 plant). This unit will be fitted with an Electronic Devices Type 3 power supply with battery back-up. Both of the units can be set to trigger outputs at two independent alarm levels on each sensor, but the sensors must be selected for a particular refrigerant. Our order should clearly state the type of refrigerant to be detected. Both of the units are suitable for Type L1 refrigerants and ammonia but not carbon dioxide. Both units can handle a mix of electro-chemical, semi-conductor and pellistor sensors. In the past we often specified the Electronic Devices Ltd Type ED810. This unit can be used with Battery back-up. The ED811 with UPS is a cheaper solution. A2.0 Specifications for Ordering The following paragraphs give guidance on what should be included on all orders to Electronic Devices Ltd. A2.1 Ordering an ED The refrigerant in use. 2. If the refrigerant is ammonia then the plantroom sensors and equipment shall be suitable for an ATEX Zone 2 hazardous area. 3. Both alarm levels should be of the "manual reset" type. 4. If fitted, the alarm accept button should be disabled and marked as such. 5. The levels at which the alarms should trigger. 6. The number of sensors required. 7. State which channels the low concentration (500 ppm) level sensors and which channels the high concentration (10,000 ppm) level sensors are to be connected to. 8. All output relays should be intrinsically safe. 9. The operating voltage (110 or 230V). 10. The unit supplied must be clearly labelled showing the operating voltage. 11. Note, in the case of ammonia, we will need to order a UPS (from the panel supplier). 12. Duct mounting kits and splash plates (if applicable). L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 6 of 21

7 A2.2 Ordering an ED The refrigerant in use. 2. Both alarm levels should be of the "manual reset" type. 3. If fitted, the alarm accept button should be disabled and marked as such. 4. The levels at which the alarms should trigger. 5. The number of sensors required (and where applicable the number of plant rooms being covered). 6. If the refrigerant is ammonia, it should be configured for intrinsically safe operation. All plant room sensors and equipment shall be suitable for an ATEX Zone 2 hazardous area. The sensors shall be wired to the gas detector with zener barriers fitted. 7. A Type 3 power supply 230V to 24V dc should be supplied. 8. The unit supplied must be clearly labelled showing the operating voltage. 9. In most cases, the internal output relays should de-energise when gas is detected, i.e. fail safe operation. In some cases (e.g. where the plant forms part of a critical process and on most Thermosyphon computer cooling applications) we may choose to energise relays on detecting gas. In these cases we should sound an audible warning for mains failure and/or if there is a fault on the gas detector. 10. Duct mounting kits and splash plates (if applicable). A3.0 Notes on EDL Gas Detector Installation The gas detector should be placed on a wall, outside the plant room, in a safe area to suit the customer. The installation should be in accordance with BSEN378:2000 and the manufacturer's installation instructions. On the ED 700, the common and normally closed contacts of the A1 and fault internal relays should normally be wired in series. In the event of a fault occurring in the gas detector a low concentration refrigerant alarm will be reported to TELSTAR and the klaxon will sound. If the alarm is due to a fault in the gas detector, this will be apparent from the fault lamp on the detector itself. The ED811 instructions currently state that terminals 4 12 are low voltage but this is no longer the case. These contacts can now accept up to 250 volts AC. Where two levels of gas are being detected (as most Star systems) the following contacts should be used: Terminals 4(NC), 5(C), and 6(NO) low level alarm 500ppm Terminals 7(NC), 8(C), and 9(NO) unit fault Terminals 27(NC), 28(C), and 29(NO) high level alarm 10,000ppm Terminals 30, 31 and 32 can also be used for a high level alarm These channels must be set up so that in the event of an alarm the reset button must be pressed to clear the alarm. A push button should be fitted to the ventilation control panel to allow an operator to cancel the Klaxon only, in the event of an alarm. The alarm levels should be set during commissioning using the supplier's installation and calibration instructions. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 7 of 21

8 Figures 01 to 03 and figures 07 to 10 refer to Star standard drawings which show typical arrangements of gas detection and ventilation panels for use on ammonia systems. SS covers Standard ED811 Gas Detection and Gas Control Panel for R717 Plant Single Fan System SS covers Standard ED811 (x2) Gas Detection and Gas Control Panel for R717 Plant Three Fan System Figure SS shows a typical installation where an ED 811 is used on an L1 refrigerant system. SS covers Standard ED700 Gas Detection and Gas Control Panel for R717 Plant Single Fan System SS covers Standard ED700 Gas Detection Power Supply Circuits for use with several under voltage trips Figure SS shows EDS/C Sensor Module and ED810/ED811 interconnections Figure SS shows ED811 Contact Wiring Note: Where more than one under voltage trip is being used or where the trip supply is 240V AC refer to drawing SS A4.0 Notes on Calibration of EDL Units In many cases the equipment supplier will be asked to commission and calibrate their equipment. On some occasions we may choose to calibrate the sensors ourselves. The following procedure should be followed: A4.1 Equipment Required A4.1.1 Low concentration and high concentration sample gas canisters (available from Electronic Devices) e.g. 0.05% and 1.0% for ammonia (i.e. 500 and 10,000 ppm) and 0.05% and 0.1% for Type L1 refrigerants (i.e. 500 and 1,000 ppm). A4.1.2 A off gas flow regulator (rising ball type available from Electronic Devices Ltd) Some small polythene bags and a rubber band. For sensors placed at a high level in the engine room we may choose to use a small metal chamber with extension pole similar to that shown in SS A4.2 Procedure for ED810 and ED811 A4.2.1 A4.2.2 The sensors must be allowed to "warm" for 24 hours with the detector switched on before the calibration procedure can begin. Open the front of the gas detector panel, remove the 4 screws from the fascia and remove the front panel from the enclosure. Approximately 100mm of cable between the back-board and the PCB on the rear of the front panel allows the front section to swing to one side without disconnecting the cables. A4.2.3 Careful handling is necessary to prevent damage to the printed circuit board. Normal pcb handling procedures should be followed. The calibration is carried out with the board live (however it operates at low voltage). L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 8 of 21

9 A4.2.4 Rotate all eight potentiometers shown on Figure SS fully anti-clockwise and press the 'Reset' push button on the front panel Enclose the first sensor head in a polythene bag and place a rubber band around its circumference, as shown in Figure SS A4.2.6 A4.2.7 A4.2.8 A4.2.9 A A Inflate the plastic bag by slowly feeding the low concentration refrigerant/air mixture into the bag. Pinch the plastic bag to prevent gas escaping around the gas feed tube. Deflate the bag by squeezing the mixture back out. Repeat this procedure twice more, re-inflate the bag and then remove the gas feed tube. This ensures that the mixture at the sensor is an accurate representation of the required gas concentration. Rotate the A1 potentiometer clockwise slowly until the A1 lamp lights (e.g. with ammonia at 0.5% in air this would normally be around the 10 mins (to be confirmed) past the hour position). Vent the bag and repeat Sections A4.2.6 and A4.2.7 with the high concentration refrigerant/air mixture and the A2 potentiometer to set the level two alarm point. (With 1.0% ammonia this would normally be around the 32 minutes past the hour position). The bag can then be removed. After approximately two minutes to allow the refrigerant within the sensor to clear, the reset push button should be pressed to allow the gas detector to return to normal monitoring mode. Repeat for each sensor. Sensors at High Level If access to ammonia sensors placed at a high level in the engine room is particularly difficult, a small round metal chamber on the end of an extended handle can be used (see Figure SS106-06). The procedure is generally as above but requires two people. The chamber is raised up until it surrounds the sensor then gas is allowed to feed from the cylinder up the pipe to the Gas Containment Chamber. The flow-rate on the rising ball flow meter should be between 2 and 3. Enough time must be allowed to flush the fresh air from the pipe and gas chamber (allow say 60 seconds) before the potentiometer on the gas detector can be set. Note that this method is less accurate than complete enclosure of the sensor in a polythene bag and will require more sample gas. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 9 of 21

10 For Figure SS See Star Drawing SS G:\Design\Standard Drawings\Drawings\Approved\SS DWGS-Approved-SS (see latest revision).drg For Figure SS See Star Drawing SS G:\Design\Standard Drawings\Drawings\Approved\SS DWGS-Approved\SS (see latest revision).drg L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc 21 Page 10 of

11 For Figure SS See Star Drawing SS G:\Design\Standard Drawings\Drawings\Approved\SS DWGS-Approved-SS (see latest revision).drg L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 11 of 20

12 L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 12 of 20

13 For Figure SS See Star Drawing SS G:\Design\Standard Drawings\Drawings\Approved\SS DWGS-Approved\SS (see latest revision).drg For Figure SS See Star Drawing SS G:\Design\Standard Drawings\Drawings\Approved\SS DWGS-Approved\SS (see latest revision).drg L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 13 of 20

14 For Figure SS See Star Drawing SS G:\Design\Standard Drawings\Drawings\Approved\SS DWGS-Approved-SS (see latest revision).drg For Figure SS See Star Drawing SS G:\Design\Standard Drawings\Drawings\Approved\SS DWGS-Approved-SS (see latest revision).drg L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 14 of 20

15 Appendix B MSA Gas Detectors B1.0 MSA Equipment MSA offer a range of equipment to monitor the presence of refrigerant gases. Most of these systems can handle electro-chemical, semi-conductor and pellistor sensors. To date we have used their Pentagas II gas detection system on one or two jobs, however sales staff and designers should note that some of the MSA literature on gas sensors is unclear and we should not offer this equipment again without consulting with the Technical Department. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 15 of 20

16 Appendix C Drager Gas Detectors C1.0 Drager Equipment Drager offer a range of equipment to monitor leakage of refrigerants. All of these systems can handle electro-chemical, semi-conductor, infrared and pellistor type sensors. Sales staff and designers should not offer this equipment without consulting with the Technical Department. The Regard-3800 controller has 16 channels, which can be configured to monitor toxic and flammable gas levels. The Regard-3800 requires a 4-20mA input module (each module can handle inputs from 4 different detectors). The Polytron 3000 transmitter and Drager sensor can be used to measure toxic gas levels (0-1000ppm NH3). It converts the signal from an electrochemical sensor to a 4-20mA signal. An LCD on the Polytron 3000 displays the measured gas concentration continuously. No Zener barriers are required for zone 2 areas (only for zone 0 and zone 1). Drager sensors are precalibrated under the Sensor Exchange Programme and are guaranteed for 12 months. The Polytron SEExPRM sensing head houses a catalytic (pellistor) sensor and can be used to measure ammonia flammable gas levels (0-100% LEL). No zener barriers are required the detector is certified to ATEX II 2G EEx de IIC T4/T5/T6. The Polytron IR utilises infrared technology and can also be used to measure ammonia in the flammable gas range (0-100% LEL). No zener barriers are required the detector is certified to ATEX II 2G EEx d [ia] IIC T5. C2.0 Specifications for Ordering The following should be included on all orders to Drager. 1. The refrigerant in use. 2. If the refrigerant is ammonia, then the plant room sensors shall be suitable for an ATEX Zone 2 hazardous area. 3. The alarm will be set to trigger outputs at two independent alarm levels in each sensor. Both alarm levels should be of the latching type, with manual reset. 4. The levels at which the alarms should trigger (A1 and A2). 5. The number of sensors required. 6. The operating voltage. 7. Duct mounting kits and splash guards if applicable. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 16 of 20

17 Appendix D CPC Ltd Infra Red Detection System D1.0 Preferred CPC Equipment CPC offer an Infrared Gas Detection System for ammonia. They claim that the detector is gas specific. The system uses a pump driven air sampling system. Air samples are taken sequentially from up to 16 zones and are fed to the analyser through a valve manifold which can trace any refrigerant detection back to the contaminated zone. D2.0 Specification for Ordering The following should be included on all orders to CPC: 1. The refrigerant in use. 2. We should specify either the 8 channel unit or the 16 channel unit. 3. The number of sensing positions. 4. The distance from analyser to each sensing position. CPC like to either see a scaled drawing or carry out a site visit. 5. The alarm levels at which the alarms should trigger. The alarms should be of the manual reset type. As standard the CPC detector can alarm at two levels. In some cases three alarms are available but extra equipment is needed and needs to be included in the cost estimate. 6. Additional relay box if it is required to shut down individual plant rooms. 7. The operating voltage at 230V (to suit use of a UPS). 8. Ask for installation and commissioning by CPC unless we are doing this ourselves. D3.0 Detector Unit Vent The vent line from the detector unit should be piped back into the engine room. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 17 of 20

18 Appendix E Vaisala E1.0 Vaisala CO 2 Detection Equipment - preferred It should be noted that these are normally installed for safety of personnel and are used to activate flashing beacons and klaxons inside and/or outside in areas that contain CO 2 equipment or pipework. The transmitter is usually wall mounted and can have a ppm display. The number of detectors ultimately chosen will depend on the particular building layout. As a general rule, at least one sensor is required for each enclosed room or space along the route of the CO 2 pipework. This may include sections in a service corridor where there are several sets of double doors. Inside rooms where floor voids exist, it is necessary to have additional units with remote probes positioned in the void. The actual number of Vaisala detectors in a room will depend on the size and layout of the room. Typically there should be one detector per 150 square metres of floor space containing CO 2 equipment and pipework. The unit can be configured for 24V ac. Fluidic Ltd currently supply these units identified as Part No. GMT 222G0N0. Details: Fluidic Ltd Dalziel Business Centre Mason Street Motherwell ML1 1YE TEL : L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 18 of 20

19 F1.0 CO 2 Server Rack Applications Appendix F CBISS At present Star s preferred CO 2 gas detection system (to alert personnel of gas leaks and activate automatic cabinet isolation where required) is the CBISS 8,16 or 32 channel gas detector. The system takes air samples from the top and bottom return bends in each cabinet (during what is referred to as the dwell time), and analyses them for a set period (referred to as the scan time). The dwell and scan times and the CO 2 concentration alarm level settings are variable and must be considered on a contract specific basis. We shall install an additional (bypass) pump to reduce cycle times as standard. All channels to be of the manual rest type. All tubes must be the same length. The CBISS system sample time is effectively independent of the tube length (up to say 100mm) because the bypass pump drains a continuous sample down the tubes that aren t currently being analysed. Each channel can be individually set to alarm at up to two specified CO 2 levels and each channel has its own relay contact. Relay contacts shall be suitable for 110V control signal switching. Note when ordering a CBISS system for use on a Trox CO 2 application it is important that we order software that energises the output relays on fault. The CO 2 OLrac solenoids shall be wired through normally closed contacts of the CBISS output relays to give break on fault functionality. This means the CO 2 OLrac solenoids remain energised if the CBISS gas detector or its power supply fails. This is essential for maximum reliability of the system. When specifying a CBISS system we should include the following: a. Gas type to be detected: CO 2. b. Gas alarm level 5,000 ppm. c. One output relay per circuit. d. Output relays should energise on alarm. e. Additional alarm (if required could be a common 2,500 ppm output relay for all channels). f. The unit should be factory set for our application. g. The unit should be factory calibrated for our application. h. Our order should state the cabinet number for each channel on each detector and any channels that should be blanked because they will not be used. i. The unit should be password protected. j. The unit should include a common internal filter (if confirmed). k. The unit should include a flow switch. l. The unit should display the Star logo. m. The unit should include the quickscan function. n. The unit should include a bypass pump with wire cage enclosure. o. The unit should be pre-configures for the minimum scan time. p. Alarm contacts should be pre-wired. q. Alarms should be manual reset type. L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 19 of 20

20 Details: CBISS 11 Ark Royal Way Lairdside Technology Park Birkenhead Wirral CH41 9HT Tel : L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 20 of 20

21 Rev Date Changes Originator DJH DJH DJH DJH DJH AMG/DJH WAC/AMG DJH J DJH/WAC K 29/04/04 DJH/WAC L 27/11/06 Revisions to ED811 terminal contact numbers WAC L 27/11/06 Figures 9 and 10 added WAC L 27/11/06 CBISS system details added DJH L 27/11/06 Vaisala equipment details added DJH M 25/06/07 CBISS system output relays now energise on fault DJH N 20/11/07 Document now refers to alarm concentration levels and to Service gas detection rather than leak detection. N 20/11/07 Vaisala CO 2 unit covers 150m 2 of floor space AMG N 20/11/07 Specification of CBISS system added AMG O 26/11/07 Further references to leak changed to gas detection. DJH O 26/11/07 Figures SS now refer to latest revision. DJH O 26/11/07 Document re-titled to refer to gas detectors. DJH P 17/03/10 L1 refrigerant alarm levels reduced to 300 ppm and 800 ppm DJH for gas specific systems. P 17/03/10 Sections 2.2.1, 2.3 to 2.6 renumbered to 2.4 to 2.8 DJH respectively. Q 28/06/10 Section 4.1 true off delay timer added to shunt trip control. WAC L:\Standard Specifications\SS106.Q.Electronic Refrigerant Gas Detectors.doc Page 21 of 21