Gas-Pro IR

The infrared emitters within the sensor generate each of the IR light beams. Each beam is of equal intensity and is deflected by a mirror inside the sensor onto a photo-receiver, which measures the received IR level. The "measurement" beam, with a frequency of about 3.3μm, is absorbed by the hydrocarbon gas molecules, thus the intensity of the beam is reduced. The "reference" beam (about 3.0μm) is not absorbed, so it arrives at the receiver at full power.

The %LEL of gas present is determined by the difference in intensity between the beams measured by the photo-receiver.

IR sensors are reliable in some environments which can cause pellistor sensors to malfunction or in some cases fail:

• In some industrial environments, pellistors risk being poisoned or inhibited. This leaves the worker on his shift without protection. IR sensors are not susceptible therefore they significantly improve safety in these conditions.
• Exposure to high levels of flammable gas can cause pellistors to "soot", reducing their sensitivity and potentially leading to failure. Pellistors require oxygen to function. However, IR sensors can be used in applications such as fuel storage tanks where there is little or no oxygen, due to inert gas flushing prior to maintenance, or which still contain high levels of fuel vapors.</li >
• The fail-safe nature of the IR sensors, which automatically notify you of any failures, provides an extra layer of safety.

Gas-Pro IR measures in %LEL and has been certified for use in hazardous areas as defined by both ATEX/IECEx and UL.