VQ2 Combustible Gas Detector Elements To be read in conjunction withIntroduction to Pellistor Gas MARKING Sensor and Pellistor Application Notes 1, 2, 3, 4, 6 and 7. Each element is identified by a unique serial number written on the can of both the detector and compensator. The serial INTRODUCTION number is written in red on the detector and black on the compensator. In addition, the detector carries a red circular The VQ2 consists of two matched elements which are used for label on the base identifying the device type. the detection of combustible gases, particularly methane in air mixtures in concentrations from 0.1% upwards. There is no interference from water vapour or carbon dioxide. Using the NOTES recommended bridge circuit (see below) and the mounting 1. Operation may be under either direct flow or diffusion arrangement shown on page 2, the minimum sensitivity is conditions in appropriate mountings (see page 2). 15 mV/% methane. 2. With open-circuit conditions at the bridge output. The low power consumption of the VQ2 makes it suitable for 3. The response time is a function of the type of mounting use where the power consumption must be minimised, e.g. used. battery operated systems. 4. If the VQ2 is exposed to greater than 5% methane concentration, the calibration of the instrument should be GENERAL DATA checked. Electrical 5. The elements are supplied as a matched pair with a Theinformation givenbelowrelates tothe VQ2operating inthe trimming resistor R of the correct value which is between recommended circuit shown. 68 and 220 O. The trimming resistor is to be connected across the compensator element as shown below. Operation (see note 1) ......... continuous Bridge supply ........... 2.0+ 0.1 V 6. The elements must be protected from certain organic and Bridge power consumption (at 2.0 V) . 0.48 W max silicone vapours by suitable filtering, and caution should be Minimum sensitivity (see note 2) . 15 mV/% methane exercised when operating in close proximity to hot, oily Linearity ......... linear up to 3% methane machinery. 1 1 Response time to register 1 /%ina2 / % 4 2 7. The bridge zero shall not change by more than 1.5 mV for concentration (see notes 2 and 3) .... 2 seconds this temperature range. Maximum methane concentration (see note 4) ........... 5 % Mechanical Mounting.............. see page 2 Outline............... see page 2 Shock test ....... 250g,5 blows in each plane Vibration test.... 20g,24 cycles from 100 to 3200 Hz Ambient temperature range (see note 7) . 75 to +408C BRIDGE CIRCUIT COMPENSATOR 2309C (BLACK SLEEVE) SEE R NOTE 5 27O 1kO 2V ZERO SET 27O DETECTOR (RED SLEEVE) OUTPUT SGX Sensortech(IS) Ltd Registered in England No.08067077 A1A-VQ2 Issue 4, March 2007OUTLINE (All dimensions without limits arenominal) 2311B D F Ref Millimetres E 1B A 11.05+ 0.25 C B 6.10+ 0.25 C 3.56+ 0.13 1G 1A D 63.5 min E 1.02 F 7.37+ 0.51 G 8.20 max J O-RING H 9.53 INSULATOR METAL J 1.52 FLANGE H SEE NOTE Note No bends may be made in this length. RECOMMENDEDMOUNTING ARRANGEMENTS 2310C AA LEAKPROOF JOINT Ref Millimetres AA 19.05 max AB 9.53+ 0.13 AC 8.33+ 0.13 AB AD 8.20 min AE 19.05 max AF 9.53+ 0.13 AG 8.20 min 60 MESH STAINLESS 1AD STEEL GAUZE AC 3 FLOW RATE 500 cm /min AE AF FILTER PAPER AND 1AG 60 MESH STAINLESS STEEL GAUZE SGX Sensortech(IS) Ltd Registered in England No.08067077 A1A-VQ2 Issue 4, March 2007