The TPV model calibrated helium leak standard works equally well calibrating helium leak detectors that test under vacuum, and helium leak detectors that sample from atmosphere utilizing a sniffer probe This is enabled by the design, which features both an integral KF25 (NW25) vacuum fitting and a pin-point helium source that accepts and aligns most manufacturers sniffer probes with virtually no dead volume where helium can accumulate and cause inconsistent readings. Calibrated helium leak standards with shut-off valves are designed to be used with hard vacuum systems and should not be used to calibrate a "Sniffer Type" leak detector. The FEP type leak element is not driven by differential pressure but helium partial pressure flows helium at virtually the same rate flowing into a vacuum or flowing.
We use the finest grade of FEP available to manufacture our FEP leak elements. The leak elements have been tested at temperatures ranging from 10°C to 40°C , yielding a temperature coefficient of approximately 2.5%/°C with no anomalous behavior.