Air/Gas Leak Testing Techniques

Water Immersion / Soap Solution

Pressurize part under water and look for air bubbles or spray outside of part with soap/water solution and look for bubbles caused by air leakage out of the part.

Advantages

Can be fast for larger leaks on small parts when testing multiple at one time.

Can be fast for testing extremely large parts with larger leaks few areas for possible leak.

Best method for detecting exact leak location detection.

Low equipment cost.

Disadvantages

Risky: An extremely operator dependant technique with a high possibility of passing actual failures.

Slow: Detecting small bubbles on typical parts can take much longer than other methods.

Added cost: Parts must typically be dry and free of fluid before shipping.

Less sensitive than other techniques on most parts.

No leak rate or test result information.

High Frequency Sound

Pressurize part and use hand held "listening" device around potential leak areas and watch for high pitched noise caused by leakage of air out of the part.

Advantages

Good for detecting leak location.

Low Equipment cost.

Disadvantages

Background noise can reduce sensitivity of the device.

Can be very slow for finding small leaks.

No leak rate or test result information.

Cannot test internal cavities.

Trace Gas Detection (Mass Spectrometer)

Pressurize part with Trace Gas such as Helium or Argon inside a high-vacuum chamber and detect the quantity of trace gas caused by leakage out of the part using an electronic Mass Spectrometer sensor. Can be hand held "sniffer" as well.