Chapter 2. Taking MeasurementsModel PM880 Portable Hygrometer User’s Manual 272.6 Conducting a Leak TestIt is important to eliminate all leaks for safety reasons and to be sure thatmeasurements are not affected by ambient contamination. Use Snoop LeakDetector or a soapy solution to verify that all connections, valves andfittings are leak tight. Tighten any fittings where a leak is detected.2.7 Shutting Down the Sample System1. Close the sample outlet needle valve.2. Slowly open the filter/coalescer outlet needle valve several turns toblow out any contaminants that may have accumulated in the coalescer,valve, or venting tube.3. Slowly close the sample inlet valve and allow the sample system todepressurize at a rate of approximately 10 psig per second.4. Close the sample tap valve (permanently mounted on the pipeline).5. Crack the inlet needle valve to relieve the pressure between the sampletap valve and the inlet needle valve.6. Completely close all three sample system valves.7. Remove the sample system from the process, while keeping all valvesfully closed to avoid moisture contamination from the ambient air.
