Common leak detection method

The purpose of leak detection is to determine the location and leakage rate of the leak of the detected parts, which are achieved by adopting some standard leak detection methods. What method should be adopted depends on the structure of the inspected parts, the economic benefits of leak detection and the nature of the leak detection system. According to different leak detection purposes, different gas leak detectors are selected to complete the leak detection task.

One. Helium gas leak detection method

Helium, symbol He, colorless and tasteless, non combustible gas, the air content is about 5.2 parts per million. Helium is the preferred trace gas because it is inactive in chemistry and is usually inert gas which is not combined with other elements or compounds. The detection method is to connect the specimen to the leak detector of the leak detector, vacuum it with the vacuum system of the instrument and communicate with the mass spectrum tube, and then spray the helium with a spray gun to the suspected leak. When there is a leak, helium is detected through the leak into the mass spectrometer tube.

The sensitivity of helium mass spectrometry is high, and it is the most accurate detection method and technology in the civil market. However, because of its high cost, it is mainly used in refrigeration, vacuum, military, nuclear power and other industries. Most of the automobile air conditioning leak detectors mainly use helium instruments, and they are also the most widely used instruments.

Two.Sf6 gas leak detector

SF6 gas is a colorless and odorless inert gas. It has stable chemical properties and strong negative power. So as a good insulation and arc extinguishing medium, it is widely used in high voltage circuit breakers, metal fully enclosed electrical appliances, closed busbars, power transformers and other main power equipment in power system. With the continuous development of the scale of power grid construction, the main equipment with six sulfur fluoride insulation is being used more and more in the power grid because of its small area, small size, convenient installation and small work and maintenance work. Gas leakage, which is used in the operation of six sulfur fluoride gas insulated equipment, has gradually become an important defect phenomenon in front of the staff of substation maintenance and operation and maintenance. Therefore, in recent years, all units have been actively carrying out the work of finding the arc extinguishing of the main equipment, the leakage and the leakage parts of the insulating medium. The purpose is to point out the direction for the equipment to eliminate the defects of the gas leakage, and to provide the basis for the reasonable arrangement of the property of the equipment, the state evaluation and the work plan of the power outage and cancellation.

The traditional SF6 gas leak detection methods are as follows: the whole method (Bao Zhafa), the simple qualitative method (handheld halogen leak detector), the pressure drop method (through the density relay pressure meter observation), the division location method (only applicable to the circuit breaker of the circuit breaker) and the soapy water leak detection.

Six sulfur fluoride electrical equipment has been routinely configured in the power system. The detection and defect tracking of gas leakage, leakage point searching, property definition and maintenance strategy formulation have become an important part of the state maintenance work.

Three. Electric spark leak detector

The resistance value and air gap density of the metal surface insulation anticorrosion layer are too thin, metal leakage and leakage microporous. When the high pressure passes, the spark discharge is generated by air gap breakdown and a pulse signal is generated for the alarm circuit. The alarm sends out the sound and light alarm, and the purpose of leakage detection is achieved according to this principle. The instrument is mainly used to detect the defects of the thick non conductive coating on the metal substrate, such as pinholes, sand holes and other defects, not the gas tightness detection of the suitable products.