Prime1 Infrared Methane Sensor CH4 Sensor Description and Operation
The Prime1 sensor uses the non-dispersive infrared method to detect the presence of hydrocarbon gases. Thesensor contains an infrared radiation source, a dual element custom infrared detector, a unique optical waveguide into which gas diffuses and internal ARM7 core microprocessor based electronics to provide a voltage output which is independent of the power supply polarity. The sensors can be configured to provide a pellistor format output, typically mid supply at zero with the voltage output increasing with respect to the detector pin by 100mV at range, or a linear voltage output, typically 0.4V – 2.0V over range with respect to the negative supply pin. In addition, the output can be read and the internal configuration can be accessed by a serial communications link.

The communication link contacts are pads in the 3 pin version Prime1 and pins in the 5 pin version Prime1. Theinternal electronics perform all the functions of driving the optical parts of the sensor, extracting the detectorsignals, converting the signals to a concentration, applying temperature compensation and scaling the output.When in a pellistor configuration, the Prime1 can replace catalytic sensors in existing circuitry subject to thepower supply requirements. External components will be required to meet the power supply requirement when aPrime1 is used in constant current pellistor circuitry. The Prime1 is not currently Ex approved so should behoused in a suitable Ex enclosure when used in Hazardous areas.

Prime1 Infrared Methane Sensor CH4 Sensor Features
• High Resolution of 0.01%vol for 0 - 10% vol and 0.1% vol for 10 - 100% vol
• Operates independent of supply polarity
• Pellistor mimic Bridge or linear voltage output
• Operating voltage range 3.0V - 5.0V
• Operating current 80mA typical
• Latest technology MEMS detectors
• Sensing ranges: 0-100% LEL Methane, 0-100% LEL Hydrocarbons or 0-100% Volume Methane
• Default range: High resolution 0-100%volume methane
• All metal construction with isolated housing
• Small internal volume
• Flexible electronic configuration access
• User calibration also enabled by hardware connections
• Wide operating temperature range
• Fast response
• Immunity from 'poisoning'

Prime1 Infrared Methane Sensor CH4 Sensor Specification
Unless otherwise stated all data was taken using: Supply voltage of 3.5V. Ambient temperature (between 20°C and 25°C). Ambient pressure (between 995 hPa and 1020 hPa). Gases diluted in nitrogen. Gas Flowrate 1litre/min across sensor face.