ACR Journal

CMYK / .ai CMYK / .ai CMYK / .ai acrjournal.uk 33 LEAK DETECTION 4. The refrigerant as tracer gas A practice which is occasionally used is to fill refrigerant into the refrigerant circuit after a pressure decay test in order to then determine the location of the leakage with a refrigerant leak detector. However, many standards stipulate that the refrigerant circuit must not be filled with refrigerant until the leaktightness of the system has been ensured. In these cases, the use of refrigerant to localize leakages is prohibited from the outset. In tests where refrigerant is permitted to be used to localize leakages, refrigerant is deliberately filled into a leaky system. Following the test, the refrigerant must then be removed from the testing circuit and recycled – which takes time and causes additional costs. 5. Simple, mobile leak detectors A variety of simple, compact handheld leak detectors are available on the market. All of these devices are optimized for on-site service on construction sites. They are compact, easy to transport and equipped with simple, low-cost sensor technology. However, these service devices are hardly able to fulfill the requirements in production settings. For example, they cannot determine the size of leakages because they cannot be calibrated – even though the displays of some devices suggest the opposite with their numerical values. Neither the detection sensitivity nor the response behavior of these service devices can match the performance of leak detectors that are intended for production purposes. In addition, their sensors frequently also respond to other substances, which leads to detection interference. Modern tracer gas methods The equipment that is actually suitable for carrying out leak testing in a production setting of the refrigeration and air conditioning industry is testing equipment that works with mass spectrometers or other highly sensitive sensor technologies, such as Wise technology. The newly developed XL3000flex sni…er leak detector, for example, is specially designed to meet the requirements of the refrigeration and air conditioning industry and o…ers the maximum level of process reliability. • The device draws in the tracer gas at a very high volumetric flow rate of up to 3000 standard cubic centimetres per minute (sccm). This is up to 50 times the value of conventional devices. Leaking tracer gas clouds are always reliably detected and leakages can be reliably detected even from large distances. This makes the testing far less operator- dependent and detects leakages even when they are in hard-to-reach locations. • The device is characterized by particularly good gross leak tolerance and very high availability. A robust, highly resistant mass spectrometer virtually eliminates contamination-related downtime due to the ability to quickly restore measurement readiness. The mass spectrometer also has excellent measurement sensitivity, even at large distances. Both helium and the less expensive forming gas – a mixture of 95 % nitrogen and 5 % hydrogen – are suitable as tracer gases. • The device is equipped for networking and automation due to its many communication interfaces that correspond to the latest industry standards. In the near future even a robot - or a two-armed cobot - will be able to perform leak testing with the device in combination with an optical system. The advantages of automation: even greater e‘ciency, less operator-dependent errors and extremely reliable leak detection. Summary In refrigeration and air conditioning technology, leaktightness requirements are particularly high because environmentally harmful and climate-damaging refrigerant is not allowed to escape. In this context, we are looking at the smallest of leaks, causing an undesired refrigerant loss of only a few grams per year. However, such small leaks can neither be detected nor pinpointed with many of the leak testing methods that remain in common use. Tracer gas methods are therefore recommended for the manufacturing of refrigeration and air conditioning systems. Ideally, the tracer gas leak detectors that are used for this purpose should work with a high suction flow rate. This significantly reduces the operator dependency of the testing and significantly increases process reliability. www.inficon.com Compared to traditional devices, the INFICON XL3000flex sniffer leak detector is characterised by a particularly high measuring sensitivity Refrigeration and air conditioning equipment such as refrigerators are subject to high tightness requirements Mobile leak detectors are designed and optimised for on-site service, therefore these devices usually do not cover the requirements in production scenarios