[ leak detection ]
Commonly found types of hydrogen point sensors include :
• Electrochemical
• Metal oxide ( MOX )
• ‘ Pellistor ’ or catalytic bead
• Thermal conductivity
In addition to point detectors , fixed ultrasonic leak detectors can help identify leaks in high-pressure systems ( usually above 7 bar ) by identifying anomalies in ultrasonic sound waves attributed to gas leaks . These sensors usually have a spherical radius in which they can detect leaks and can be useful for outdoor storage tanks , short pipelines , or use areas . As background noise can affect the performance of these detectors , care should be taken to ensure appropriate placement .
To pinpoint the leak source more accurately and to detect leakages that fixed sensors may miss , operators should perform routine inspections with handheld sensors . Many types are commercially available , including handheld versions of the above-mentioned sensors , usually equipped with vacuum pumps to get an accurate measurement of hydrogen in the area the device is pointed towards . Portable ultrasonic leak detectors are also available and provide audio-visual feedback when nearing the source of a leak . Thermal imaging can detect leaks based on temperature differences between the leaking gas and its immediate surroundings . This method can be used from moving vehicles , helicopters , or portable handheld systems and is capable of inspecting several miles or hundreds of miles of pipeline per day . 2
In addition to area detection and routine inspections , the use of a visual indicator can be beneficial to identify leaks more easily . Commercially available hydrogen detection
Fig . 1 . Gas detector located outdoors in a hydrogen use area
38 Hydrogen Tech World | Issue 9 | April 2023