Kevin Dean, MSA Safety, UK, describes how to improve the probability of detecting LNG leaks, by using laser open path gas detectors.
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pen path gas detectors (OPGD) utilising non-dispersive infrared (NDIR) sensor technology have been in use since the late 1980s and are widely accepted by many oil and gas (including LNG operations), petrochemical, and other high-risk industries as supplementary protection for the detection of hydrocarbon combustible gases. OPGDs improve the probability of detecting gas leaks that point gas detectors on their own may not detect or not as quickly as expected. As the gas cloud must migrate to the point detector and specifically to the ‘point’ inside the device where the sensor is located, strong winds can be one of the reasons for gas leaks going undetected. With OPGDs, the gas cloud still has to migrate to the beam that is transmitted from the transmitter (source) to the receiver. However, as the beam of the OPGD can be very long (up to and in excess of 100 m – application dependent) the probability of detection is increased. This is because the gas will be detected anywhere along the entire length of the beam and not just within the small sensor housing of the point gas detector. NDIR-based OPGD systems are commonly used to monitor hydrocarbon gas leaks on offshore and onshore oil and gas production facilities, LNG facilities, refineries, gas transmission stations, and many other high-risk industrial facilities.
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