IREX Pellistor exchange IR gas detector

Transcription

1 IREX Pellistor exchange IR gas detector Manual addendum: Connecting to a Wormald 2003A-1 gas module M07*** Issue 1 January 2009

2 INTRODUCTION IREX is an Exd Flameproof gas detector, designed for detecting hydrocarbon gases. IREX is a sinter-free, fully featured infrared gas detector that produces a mv Wheatstone Bridge output as used on conventional pellistor based systems. IREX replaces old pellistor heads by simply mounting on the original junction box, and connecting to the original cable. The IREX concept enables upgrade to dual-wavelength IR gas detector technology without incurring the very significant costs associated with replacing control systems and re-installation. This manual describes the procedure for connecting IREX to the Wormald 2003A or 2003A- 1 control module. Reference must also be made to the IREX operating and maintenance instructions, and to the Wormald 2003A module operating instructions. WARNING The Installation, operating and maintenance instructions (part number M07690) supplied with the IREX detector must be followed when installing, commissioning or servicing a detector. The equipment described in this manual is designed for detection of flammable gases. Ensure local safety procedures are adopted before carrying out any maintenance or calibration work. The equipment described in this manual may be connected to remote alarms and/or shutdown systems. Ensure that local operating procedures are adopted before carrying out any installation, maintenance or calibration work UK Office 2 Blacklands Way Abingdon Business Park Abingdon Oxfordshire OX14 1DY Tel: +44 (0) Fax :+44 (0) sales@crowcon.com USA Office 21 Kenton Lands Road Erlanger Kentucky Tel: or Fax: salesusa@crowcon.com European Office Vlambloem JG Rotterdam Netherlands Tel: Fax: eu@crowcon.com Singapore Office Block 194 Pandan Loop ~06-20 Pantech Industrial Complex Singapore Tel: Fax: sales@crowcon.com.sg Crowcon reserves the right to change the design or specification of this product without notice. Connecting IREX to the Wormald 2003A-1 Module 2

3 1. CONNETION Refer to Section 2 of the IREX operating and maintenance instructions to install the detector and connect to original field wiring. Wormald control racks will usually be installed in cabinets with din-rail mounted terminals for detector connections. Specific system drawings will need to be referred to in order to identity connections for individual heads. Slots are provided for connection of 15 detectors on a Wormald control rack. The backplane PCB has marked connectors for each detector/module. The detector cables should be connected to terminals on the appropriate module input as follows: Terminals 1 & 2: Detector +ve Terminal 3: Detector signal Terminals 4 & 5: Detector ve Detector connection terminals Figure 1: Wormald 2003 system back-plane terminal arrangement 2. MODULE SET-UP Refer to Section 3 of the IREX operating and maintenance instructions for general guidance on commissioning IREX. 2.1 APPLYING POWER Once the IREX has been connected to the control rack, power can be applied. Please ensure output functions are inhibited until commissioning is complete. To inhibit the Wormald 2003A module set the INHIBIT switch to the down position. The INHIBITED LED will light to confirm the inhibit status. Connecting IREX to the Wormald 2003A-1 Module 3

4 Detector head volts must be set within the specified range. The supply voltage is set at the control card by adjusting potentiometer RV8 (see below). Turn RV8 clockwise to increase the voltage, anti-clockwise to decrease the voltage. The voltage measured at the detector terminals (within the Exe junction box if used, or at the IREX terminal PCB) must be set between 2.95 and 3.2 V. The voltage must be set with the detector installed in its final location to ensure that cable volt-drops are factored-in. RV8 Head Volt Potentiometer 2.2 CARD AND DETECTOR SET-UP Figure 2: Wormald 2003A-1 PCB Layout The location of zero and calibration potentiometers is shown on Figure 5, Page IREX Configuration The Wormald 2003A module interprets a rising detector signal to indicate gas. Ensure that the IREX detector has been configured accordingly by referring to the product label, or certificate supplied with the detector for confirmation. A detector part number ending AB will be configured for a positive signal (eg IREX AA-AD- 011-AB), AC denotes a negative signal. The Zero to Gas Level parameter on the certificate with be +ve if the detector is set with a rising signal (eg 50mV), -ve if set for a falling signal (eg -50mV). Refer to Section 2.6 of the IREX operating and maintenance instructions for more information Warm-Up Wait for a minimum of 30 minutes after the head voltage has been set before attempting to zero or calibrate the detector. This allows for thermal stabilization of the detector. Connecting IREX to the Wormald 2003A-1 Module 4

5 2.2.3 Zeroing the control card After the warm-up period (and having checked no flammable gas is present), the control card can be zeroed by adjusting potentiometer RV1 ( MZ on the front panel). Turn RV1 clockwise to increase the reading, anti-clockwise to decrease the reading. A negative reading is indicated by a decimal point LED in the middle of the display. The example meter image below indicates a reading of -13: Decimal point indicates a negative reading. Figure 3: Module display showing a negative reading Calibrating the control card Apply calibration gas as described in the IREX operating and maintenance manual. Once the gas reading has stabilised, adjust potentiometer RV2 ( MS on the front panel) until the desired reading is shown (eg 50% LEL). Turn RV2 clockwise to increase the reading, anti-clockwise to decrease the reading. The display will flash if the reading is over-range (ie above 99%LEL). For example if the display is flashing a reading of 25%LEL, the true concentration is 125%LEL Further Commissioning tests Once the IREX has been calibrated, and the zero has been re-checked, it is advisable to check the alarm functions of the control card by simulating a gas leak (ie by applying gas to the detector with the control module in Normal mode). This action must only be performed with the consent of the site operator to avoid un-wanted alarms or shut-downs. 3. MODULE OPERATION NOTES 1. Module alarms must be accepted on the Facilities card on the same control rack (the input module alarm LED s will stay on once accepted) before they can be reset using the Reset button on the gas module. 2. IREX produces a negative signal when in fault condition. When IREX is in fault (eg due to a beam blockage) the 2003A module FAULT LED will light, and the display will read -100% to -150% LEL (as shown below). Figure 4: 2003 Module indicating an IREX fault Connecting IREX to the Wormald 2003A-1 Module 5

6 Once the cause of the fault has been rectified, the ACCEPT button on the Facilities card must be pressed in order for the input module fault condition to be reset. RV1 Zero Potentiometer RV2 Span Potentiometer Module Inhibit switch Down = module inhibited Figure 5: Module controls Connecting IREX to the Wormald 2003A-1 Module 6