Leakage Quantification
Vacuum testing using a tracer gas identifies microscopic pathways through seals and welds in a pressurized system. During helium leak detection, a mass spectrometer tuned to the mass of helium atoms measures the flow rate of gas escaping from or entering a test object. This method identifies defects far smaller than those found through soap-bubble or pressure-decay tests.
Operational Method
Bombing or sniffer-probe techniques adapt the procedure to the specific geometry of the sensor or housing. In helium leak detection, the part is either placed in a vacuum chamber and sprayed with the gas or pressurized with the gas and scanned with a probe. The choice of method depends on whether the goal is to find the location of a leak or to measure the total leakage rate.
Sensitivity Limit
Measuring the concentration of the tracer gas in the background environment is necessary to prevent false readings. Standard helium leak detection can resolve rates as low as 10 to the power of negative 12 mbar liters per second. Seals and joints are verified against this threshold to ensure long-term stability in harsh environments.
Reference Standard
Certified reference leaks with known flow rates calibrate the mass spectrometer before each test cycle. This confirms the accuracy of the detection equipment.
