Analysis of Factors Causing Inaccurate Measurements of Handheld Gas Detectors
Anti corrosion layer detector is an instrument used to detect the quality of metal surface coatings. There are two types of instruments, one is high-voltage spark detection, which means that the high-voltage spark probe brush is directly attached to the surface of the insulation layer for detection. When there is a leakage point, it will break down and discharge, accompanied by an audible and visual alarm. Another method is to use the principle of electromagnetic induction for buried pipelines, cables, and containers. During detection, excavation is not required, and the location of the insulation layer damage point of the underground pipeline container can be detected directly on the ground.
Leak detection principle:
The anti-corrosion insulation layer on the metal surface is too thin, and the resistance value and air gap density at the iron leakage micropores are very small. When the high-voltage probe of the leak detector passes through the pinhole defect, air gap breakdown occurs, generating electric spark discharge. At the same time, a pulse signal is generated to the alarm circuit of the leak detector, driving the sound and light alarm of the leak detector circuit to achieve the purpose of leak detection.
Underground leak detection:
The detection principle is the AC potential gradient method, also known as the "Pearso" method in foreign countries (developed by an engineer named Pearson). During the inspection, two inspectors are connected to the two electrodes of the detector, maintaining a distance of 3-5 meters between them and moving forward above the pipeline. When there is a damaged point in the anti-corrosion layer of the current carrying pipeline, the electrical signal on the pipeline will flow into the surrounding soil from this point, forming a leakage point anomaly above the damaged point. When the two inspectors pass by this point, the potential difference signal generated by the leakage point anomaly will be detected. Through back and forth verification, the specific location of the damaged point can be identified, and the positioning deviation is generally within 15% of the burial depth.
Scope of application:
Generally, high-voltage electric sparks are used for inspection and repair of metal valves, pipe fittings, and components during the coating process of anti-corrosion insulation coatings. They can only be buried underground after passing the inspection. According to industry standards, regular inspections are required after a certain period of use. At this time, buried pipeline detectors should be used to locate corrosion points, and then excavation and repair should be carried out.
