IRM-AT METHANE IRM-AT INFRARED SENSOR Thermopile Detector Technical Specification Figure 1 IRM-AT Schematic Diagram Top View Pin out details: 1. Lamp return 2. Lamp +5V 3. Not connected 4. Detector output 5. Reference output 6. Thermistor output 7. OV supply Bottom View Side View All dimensions in millimetres (± 0.15mm) Notes: 1. Dimensions without tolerances are nominal 2. Recommended PCB socket: Wearnes Cambion Ltd. code: 450-3326-01-06-00 3. Weight: < 15g 4. Use antistatic precautions when handling 5. Do not cut pins 6. Do not solder directly to pins PERFORMANCE Maximum Power Requirements Minimum Operating Voltage Source Drive Frequency Active/Reference Output in Air (peak-to-peak) Typical active signal change for 2.5% CH4 Typical active signal change for 100% CH4 Response Time (t90) Warm-up Time 5.0 VDC, 60 mA max. (50% duty cycle source drive) 2.0 VDC, 20 mA max. (50% duty cycle source drive) 3 Hz typical, 50% duty cycle 2 to 4 mV @ 5 Hz, 50% duty cycle 5% drop (typical) @ 5 V, 3 Hz, 50% duty cycle 30% drop (typical) @ 5 V, 3 Hz, 50% duty cycle < 40 s @ 20°C ambient 30 minutes @ 20°C, 5 VDC KEY SPECIFICATIONS Integral thermistor (NTC, R25 = 100KΩ, ß= 3940 K) -20°C to +50°C (linear compensation from 0 to 40°C) -40°C to +75°C 0 to 95% RH non-condensing Temperature Signal Operating Temperature Range Storage Temperature Range Humidity Range 0 - 2.5% Range Accuracy Resolution at zero Resolution at range Zero repeatability Span coefficient * NOTE: due to the incandescent IR source within the sensor, this device should NOT be used for applications where there is a possiblity of the presence or formation of an explosive mixture of methane and/or other flammable gases with an oxidant such as air. At the end of the product’s life, do not dispose of any electronic sensor, component or instrument in the domestic waste, but contact the instrument manufacturer, Alphasense or its distributor for disposal instructions. Alphasense Ltd, Sensor Technology House, 300 Avenue West, Skyline 120, Great Notley. CM77 7AA. UK Telephone: +44 (0) 1376 556 700 Fax: +44 (0) 1376 335 899 E-mail: [email protected] Website: www.alphasense.com

IRM-AT Perf erformance Data IRM-AT Performance Data Figure 2 Response up to 2.5% volume Methane Patented optical design gives repeatable and stable absorbancy, following the BeerLambert Law. This allows universal linearisation, not reliant on custom EEPROMs. Figure 3 Response up to 100% Methane This NDIR Methane sensor responds up to 100% Methane but the housing is plastic so is not Ex approved. Absorbance = span * (1-exp(-b*[CH4]c)) default span @ 80% vol = 1.0, b = 0.0275, c = 0.555 Figure 4 Linearity error to 2.5% Methane Using univerisal linearisations, the IRC-AT error is less than 0.05%...