Model SA-5100D-CH4

High Sensitivity Methane Detection

Digital Display Interface

(Captive NDIR Open Path)


Safeguard Analytics Model IR-5100D-CH4 is an infrared based gas sensor designed to continuously detect and monitor combustible hydrocarbon gas in ambient air. Hydrocarbon gases are detected and measured using the non-dispersive infrared radiation absorbance technique as a source signal.

Model IR-5100D-CH4 infrared gas detection sensors consist of a light source and a dual channel pyro-electric detector mounted in a common optical chamber with an external retroflector to provide an open gas sensing chamber. Each dual channel detector is fitted with two optical filters. One channel functions as a reference detector and is fitted with a filter where there are no particular gas absorbance lines. The other channel functions as an active detector and is fitted with a filter that lets through IR light in the wavelength of the target gases – hydrocarbons typically absorb in the 3.25-3.4 micron region. As gas enters the optical chamber less of the source radiation reaches the active detector while the reference detector is unchanged. This differential in light reaching the pyro-electric detectors is the measurement signal.

Each IR-5100D-CH4 is calibrated at the factory and requires no routine field calibration. Annual maintenance should include a visual inspection, a gas sample bump test and cleaning of the sapphire window. The sensors are equipped with a built in real time digital display, magnetic interface switches and full script user interface instructions. The digital display is a MODBUS master with an internal data logging function capable of storing readings of up to 12 months based on a one minute data capture rate. Other options include a 4-20 mA DC analog output and local alarm relays.

Principle of Operations