Using the Calibrator
To calibrate a refrigerant leak detector using the RLS Refrigerant Leak Standard, the leak rate of the RLS is first adjusted to the desired value for the calibration. Using the calibration graph of pressure vs. leak rate, as previously described, the pressure value corresponding to the desired leak rate is determined from the graph. The pressure in the vapor chamber, as measured by the gauge attached to it, is then adjusted to that value using either the "Increase" or "Decrease" Valve of the RLS. To increase the pressure in the vapor chamber to a selected value, the Increase Valve, on the right in the photograph, is opened to admit vapor to the vapor chamber from the liquid reservoir (which has a vapor "head" corresponding to the vapor pressure of the particular refrigerant). To lower the pressure in the vapor chamber to a selected value, the Decrease Valve is opened to exhaust vapor to the atmosphere.
The refrigerant vapor then leaks from the vapor chamber to the atmosphere through the RLS's stainless-steel capillary leak element at the selected as-calibrated flow rate. The capillary leak element is surrounded by a protective stainless steel tube that protrudes from the vapor chamber to the left of the pressure gauge in the photograph. The end of this tube has a machined, tapered recess designed to receive the tip of the sniffer-detector probe and provide secure collection of the refrigerant flow/leak rate from the capillary leak element. To calibrate the leak detector to this selected leak rate, the sniffer probe tip is placed in the tapered recess, withdrawn, and replaced until a repeatable detector response signal is obtained. The detector signal scale is then calibrated to this NIST-traceable leak rate.
