1. Soap Solution Method

The soap solution method is a very common method. A certain pressure is applied to the test object, and the outside is coated with soap solution. If there is a leak, bubbles will be produced. According to the soap solution detection method, gas pressurization is used to determine the leak location, and the approximate amount of leakage can also be known. As long as there is no danger during pressurization, any gas can be used.

The advantage of this detection method is that during the leak test, it is not necessary to stop the operation of the device or disconnect the test object, and the operation can be performed at any time.

2. Hydraulic Test Method

When testing pressure vessels, fill the container or equipment with water and then inject water with a hydraulic pump.

Because this method pressurizes water, the expansion of water is very small, and the pressure can be increased immediately; therefore, even if accidents such as container damage, connection bolt breakage, or gasket flying occur, it will not cause danger.

3. Acoustic Method

The detection principle of the acoustic method is that when gas is ejected from a small hole, it will make a sound. The magnitude and frequency of the sound depend on the size of the leak, the pressure and pressure difference on both sides, and the type of gas.

This method is very primitive, relying on listening to the sound to judge whether there is a leak, unlike other methods, it can clearly indicate the sensitivity of the detection. The sensitivity of this method will be affected by the environment, but it is relatively simple and economical, and generally uses ears and stethoscopes.

4. Ultrasonic Method

The ultrasonic method is to partially cut off the audible frequency in the leakage sound, only amplify the ultrasonic part, and detect it to find the leakage.

During detection, the ultrasonic transducer can directly cause the pointer of the meter to swing, or the method of making the ultrasonic wave return to the audible frequency range to beep can be used.

Under the noise conditions of ordinary factories, the ultrasonic transducer is not interfered with, so only the ultrasonic part is detected, and the effect is very good. When judging the leak point, adjust the sensitivity of the leak detector to the maximum, move the microphone while listening to the suspicious area;

Make the ultrasonic sound feel the maximum, and then look for the place where the ultrasonic wave is emitted. Compared with this method, the personal error of the operation is smaller, and the results are almost the same regardless of who uses it.

5. Rubber Membrane Method

The rubber membrane method refers to sticking a rubber membrane and a plastic film strip to the leak, connecting a funnel to it, and sticking a thin rubber or film to the funnel. If there is a leak, the balloon will inflate.

Large factories use this method for gas pipelines. Observation with the naked eye, the results are the same regardless of who observes, and there is no human error.

6. Gas Detection Method

The gas detection method refers to pressurizing the test container with gas other than air, and placing a bucket that will react with the gas outside the container. If there is a leak, the gas will escape and react with the substance in the bucket, and then the reaction substance will be detected by a detector. For example, using test paper to measure ammonia leaks uses this method. This detection method is very simple and is widely used in factories, but attention should be paid to the accuracy of the instrument.

7. Radioactive Isotope Method

The radioactive isotope method uses radioactive gases that are harmless to the human body for leak detection.

Pressurize the test container with air containing a small amount of radioactive gas. If there is a leak, the radioactive gas will leak out; a scintillation counter can be used to detect γ rays, so it is possible to know whether there is a leak and the approximate amount of leakage.

This detection method is very expensive, and users must have high professional knowledge.

8. Semiconductor Detection Method

After the semiconductor adsorbs a certain gas, the conductivity will change. Based on this principle, a new technology of using semiconductors for gas detection has emerged.

This detection method is accurate, the error is very small, and it is relatively economical, but the stability is not very good.

9. Halogen Pressurization Method

Pressurize the container with halogen gas. If the halogen gas leaks, the halogen detector will immediately fluctuate, indicating whether there is a leak. Large factories and power plants use halogen detectors to check for leaks in condensers, which is convenient and practical.

10. Vacuum Method

The vacuum method refers to evacuating the inspection container and then applying water, alcohol, acetone, or other liquids to the detection area; if the solution contacts the leak hole and covers the hole, it will flow, revealing the leak.

11. Thermal Conductivity Detection Method

The thermal conductivity of various gases is different. If the thermal conductivity is known, it is possible to know what gas has been mixed into the known gas. The thermal conductivity detector is more accurate, reliable, and stable.