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Vacuum leak test systems: The safe way to find leaks

Vacuum leak test systems

Leaks are undesirable openings in the walls or crevices of your products that let solids, liquids or gases escape through them. Leaks can appear suddenly or may develop slowly over time and damage the product quality. If unnoticed for a long period of time, they may grow to completely disrupt the process or partially harm the products.

Vacuum leaks affect the vacuum levels in a process and hinder processes in which precise vacuum levels are important. When desirable vacuum levels cannot be reached, leaks are sometimes indicated as a capacity issue. It indicates that the vacuum system has inadequate pumping capacity when in reality the pumping capacity is not the problem.

The most commonly known vacuum leaks are those found in car engines. Several methods can be employed to detect vacuum leaks in not just car engines but other systems too. Here are a few methods used for a vacuum leak test.

In this test, the system or part to be tested is isolated and then pressurized. While the system is under pressure soapy water is applied to potential leak sites and is left there for a certain amount of time. The areas with soapy water are carefully observed as the leaks cause the soapy water to bubble. The points at which bubbles are formed are marked so that they may be identified for repair. The pressurized soap bubble test is the easiest method for vacuum leak testing.

For the parts that cannot be pressurized the flexible tape test can be used for locating leaks. A thin, flexible tape is put on the potential leak points of the test work. Once the points have been covered the vacuum is pulled on the system and the tape at all the points is checked. A leak is detected on all the points at which the tape is sucked in or dented. In piping applications where PVC is used for inlet piping, the tapes can be kept in place to repair the vacuum leaks.

Vacuum leaks are associated with a high-frequency sound. The ultrasonic detector detects the high-frequency sound and converts to an audible range that can be heard over a headset. Some of the detectors can also indicate this sound on a meter. An advantage of the ultrasonic leak detector is that it can be used to detect vacuum leaks in compressed air systems or pipes.

The Helium detectors use a sensor that detects the increase in Helium concentration in the air stream. The sensor is placed near the inlet of the vacuum pump where it can sample the air from the test part. The potential leak sites are sprayed with Helium which is quickly pulled inside the system if there is a leak. The Helium is then detected by the sensor and an alarm that indicates a leak is triggered. Helium leak detectors are considered one of the most accurate methods for leak testing as they have high sensitivity and can even locate very small leaks.


Vacuum leak testing is used to test parts that may have leakages from an external source. The vacuum leak test provides better repeatability as it is less sensitive to environmental variables like temperature change. Other advantages of vacuum leak testing are that it takes less time to reach a stable pressure, has shorter cycle times and is less susceptible to the potential instability of parts. Mikro Innotech offers a wide range of vacuum leak testing systems that are customised to suit your products. The systems are ideal for the leak testing of many components from underwater sensors to outdoor electrical housings.

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