Integral leak test systems HVAC-R
Integral leak detection systems are installations for testing products, either manually, semi- or fully automated, if they fulfill reasonable leakage rates to guarantee their functionality over the lifetime or to fulfill legal requirements. Further, they not only allow quantification of the overall leakage rate but also for qualitative results. Possible specimens in the HVAC-R market are radiators, heat exchangers, condensors, hoses or tubing which are made of up to hundreds of meters of piping often with very large surfaces. They will be filled with different kind of refrigerants like R134a or R1234YF, respectively. Therefore, the range of leakage sizes or leakage rates, often given in g/y is strongly depending on the final application and refrigerant. Pfeiffer Vacuum can supply all components needed for thoroughly set-up leak detection systems based on the tracer gases (Helium, forming gas) or air, supported by strong application knowledge.
- Very low detection limits
- Short cycle times
How does it work?
For the unit under test (UUT) a reasonable leakage rate and a tracer gas have to be defined. In case of foreseeable influences of temperature or volume changes He as a tracer gas is favorable as the influences are neglectable. Furthermore the pressure inside the UUT while testing influences directly the magnitude of the defined leakage rate. Furthermore, the chosen refrigerant also influences the leakage rate and thus narrows down the selectable tracer gases. Nevertheless, some parts are better fitting to air based leak detection setups while others are predominantly tested by tracer gas methods as the requirements are stricter. Finally, the UUT is tested and the leak detector will state whether the UUT is “leak tight” or not.
Vacuum is not necessarily required for all methods, for example accumulation methods based on tracer gas method and the micro-flow solution are performed under ambient conditions outside the UUT. However, air based methods do reach limitations or difficulties if leakage rates smaller than 10-5 mbar*l/s have to be measured. Integral solutions, also including mass extraction method, require a vacuum surrounding the UUT. Depending on the outer surfaces of the UUT, e.g. isolation materials exhibiting high surface to volume ratios, a demanding task for pumping systems is given, but it is not a dead end.
Pfeiffer Vacuum offers a complete portfolio for integral leak detection systems with pumping systems, e.g. consisting of a rotary vane pumps of HenaLine combined with the universal HiLobe Roots pump for high flexibility, leak detectors for He or H2 detection (ASI 35 or ASM 340) or Air based (E-PDQ or E2) as well as other vacuum components. Furthermore, a HiPace turbopump can be utilized to shorten either the pump down or measurement time drastically.