Water Immersion Bubble Test Method

This is a traditional and relatively primitive technique of leak detection. This includes immersing a charged or pressurized part, usually with high-pressure dry air or nitrogen, in a water tank and watching for escaping bubbles. The larger and more frequent the bubbles, the bigger the leakage.

Limitation – Small equipment like pumps and tanks can be checked with this methodology but the equipment like vessels and storage tanks can be tested with this method standard industrial practices don’t support this as there are chances of huge investments.

Soap Solution Bubble Test

Instead of submersing the part in water, the pressurized unit to be tested is sprayed with a soap solution and the operator is able to see the bubbles formed by gas escaping in case of a leak

Limitation – There is an accessibility issue as this can be conducted for the equipment which is kept on the floor but isn’t suitable for the overall system which is not accessible.

Pressure Decay Test

In this pressurizing the system with a high-pressure gas, usually dry air or nitrogen takes place. Then the part is isolated from the gas supply, and, after a stabilizing period, its internal pressure is monitored over time. If the pressure in the system drops fast, there is a large leak present in that component/section of the system. If the system’s pressure drops slowly, there is a small leak present.

Limitation – This method is suitable for larger leakages; in the case of smaller leakages it is very time-consuming.

Vacuum Decay Test or Pressure Rise Test

This method involves evacuating the part to suitably low pressures and, after stabilizing the pressure, measuring the increase in pressure caused by test media entering the part. Only parts that are able to withstand external pressure can be tested in this way

Limitations – This method is only suitable for equipment that is designed to withstand pressure.

Tracer Gas Leak Testing

This includes a group of test methods characterized to detect and measure a tracer gas flowing through a leak. These techniques differ for the tracer gas used and for the realization technology.

Limitations – This method is more applicable to gas leakages as the cost of the measuring instrument is high which can’t justify.

Sniffing

The sniffing technique of leak detection utilizes a detector probe or sniffer to sense leaks from a unit previously filled and pressurized with tracer gas.

Limitations – This is not an accessible technique for the system which is not placed on the floor.

Accumulation Leak Testing

This method is a variation of sniffer leak testing. The part to be tested is placed in an enclosed containment hood, and then pressurized with the tracer gas. The sniffer is connected to the hood where the leaked tracer gas has accumulated during the test time. When accumulated, the tracer gas is more readily sensed by the detector. The gas sensor will measure the global leak.

Limitation – This is not an accessible technique for the system which is not placed on the floor.

Vacuum Chamber Inside-Out Leak Testing

The chamber is connected to a vacuum pumping group equipped with the tracer gas detector, for chamber evacuation and gas detection. A second vacuum group is required to evacuate the unit under test before filling it with gas. A tracer gas-filling device completes the testing apparatus.  Then the vacuum chamber and the unit are evacuated. The detector is linked to the vacuum line to detect the tracer gas flow.

Limitation – This is not an accessible technique for the system which is not placed on the floor.

Acoustic Partial Discharge Test

This sound, which is both sonic and ultrasonic, is caused by partial discharges, i.e., electrical discharges that signal the harmful flow of electricity and deteriorate components over time. In fact, partial discharges are related to nearly 85% of disruptive failures in high-voltage and medium-voltage assets, causing costly network outages and safety hazards. This sound is generated before heating takes place.

Conclusion –

Only Acoustic Partial Discharge works for a larger distance and gives accurate results in a short period of time without any competency and training requirements. It is safe to use, also the reports can be generated immediately once the detection is done.