Pathfinder Fixed Gas Detection System Transmitter

The IR-29 fixed gas detection system transmitter from GfG utilises an innovative closed-path infrared gas detection technique for integrated general hydrocarbon, volatile organic chemical (VOC), carbon dioxide (CO2), and water vapour measurement. Transmitters can be configured for measurement of a single hazard; or the transmitter can be equipped with multiple detectors that allow the transmitter to measure and interpret readings for multiple hazards at the same time.

The patented GfG (Germany) infrared detection technique includes use of a highly efficient gold film mirrored surface overlaid on the inner walls of the optical sensing chamber. The infrared light used to provide gas measurements
is automatically focused as a function of the configuration of the walls of the chamber directly on the signal detectors, omitting the need for lenses, optical splitters and parabolic focusing mirrors.

Lenses, optical splitters and focusing mirrors are a potential source of noise in an optical measurement system. They are also very expensive hardware components that increase both the size and price while reducing the signal strength of the detector. Removal of these expensive components reduces the price while substantially improving the performance of the IR-29 compared to other infrared transmitter designs. Removal of these elements also permits significantly lower step-change resolution for the measured gases, allowing the compact IR-29 to provide readings of VOC and hydrocarbon gases from the low parts-per-million range, through the explosive range, and all the way up to 100% volume concentrations.

The inclusion of multiple detectors and the ability to discriminate between infrared absorbance at multiple wavelengths substantially increases the specificity and quality of readings. While the sensitivity of the IR-29 to methane and propane is excellent, the sensitivity of the transmitter to toxic VOCs and large hydrocarbon molecules is even better than its sensitivity to methane.

As the detection technique is based on infrared absorbance, the IR-29 does not require the presence of oxygen to detect gas, can be used for high range measurement up to 100% volume gas, and is not subject to damage due to exposure to sensor poisons such as H2S or atmosphere contaminated with silicone vapours. The IR-29 is extremely stable and maintains calibration and accuracy for long periods of time without needing adjustment. The IR-29 has no elements that deteriorate in normal operation and so can be expected to last for many years in continuous operation.