Air leak testing methods include several techniques depending on the application and required accuracy. Below are some common methods:

    • Dunk Testing:
      Dunk testing, also known as bubble testing, is one of the oldest and most basic air leak testing methods. The test is conducted by pressurizing the part or vessel, submerging it in water, and observing for bubbles that indicate escaping air or gas. The rate of bubble formation and size of the bubbles are directly proportional to the size of the leak. This is a simple, cost-effective method for leak location but cannot measure accurately or quantify the leak rate.
    • Tracer Gas Method:
      For devices with very low leak rates in the range of 10⁻⁵ SCC/sec or lower, the tracer gas or sniffer test can be used. These tests involve pressurizing the test part with a non-atmospheric gas, such as helium, hydrogen, or halogen, and using a sniffer probe to detect the leak location. These tests can be performed using two methods: with a sniffer probe to localize the leak or in a chamber to identify minute leak rates. Highly sensitive, these tests can identify and localize even the tiniest leaks but require manual operation and a controlled test environment to minimize external interferences like wind, temperature, and pressure changes.
    • Pressure Decay Leak Testing:
      The test part is first pressurized to a predetermined level, isolated from any pressure loss, and then monitored for any pressure drop. These tests can be performed either directly with reference to a master test object or indirectly using a chamber. These methods, which use pressure transducers and/or differential sensors, are fast and highly accurate for detecting and quantifying the leak rate.
    • Vacuum Decay Leak Testing:
      Vacuum decay leak testing operates on the same principle as pressure decay testing, but in this case, the test part or assembly is evacuated of air and monitored for any pressure increase in the system due to airflow from the external environment.
    • Mass Flow Testing:
      With the help of a flow meter, pressurized air is sent through the test part at a predetermined level and used to measure the flow rate. Typical applications include medical tubes, catheters, and HVAC leak detection.