Room temperature and low pressure test method for the tightness of polyethylene valves

Abstract

A room temperature and low pressure test method for the sealing performance of polyethylene valves. On the premise of confirming that the valve end face is reliably sealed and the air circuit of the test bench has no leakage, the indoor air is used as the test medium, and the closed-loop control system of the test bench is used to automatically pressurize the valve test chamber and standard cylinder to the test standard pressure. Use the temperature sensor and differential pressure sensor to simultaneously detect the temperature of the valve test chamber and the test gas in the standard cylinder and the pressure difference between the two, obtain all the two-dimensional data during the pressurization test period or the period before the leakage alarm, and send it to the single-chip computer system Perform cross-correlation analysis. According to the sufficient and necessary condition of no leakage: any point on the fitting curve of the temperature difference and pressure difference of the medium on the same time axis has the same change gradient, and the temperature and pressure values ​​at any time have a single proportional relationship. The pressure drop gradient value of the valve gives the judgment of the sealing performance of the valve. This method does not require a constant temperature environment, and has the characteristics of high resolution, rapidity and high efficiency.

Description

technical field [0001] The invention relates to a room-temperature and low-pressure test method for the sealing performance of polyethylene (PE) valves, which includes test medium acquisition, two-dimensional data synchronous acquisition and correlation analysis, and sealing evaluation criteria. Background technique [0002] Relevant standards require that PE valves must be subjected to low-pressure and high-pressure tests under liquid or gas media to check their sealing performance. Among them, the low-pressure test of gas media requires a 24-hour test under constant temperature and pressure conditions. In the current low-pressure test, after the test chamber of the PE valve is pressurized, U-shaped tubes are often used to observe the pressure change to judge the tightness of the valve. When the sensor detection method is used to obtain the pressure change and analyze its tightness, the detection system is required to be able to reliably distinguish the Pa level pressure ch...

AI Technical Summary

Problems solved by technology

[0005] The purpose of this invention: to propose a method that can complete the PE valve low-pressure sealing performance test in a relatively short period of time without strict constant temperature or directly at room temperature, and solve the problem of The problems of long test period, low efficiency and high cost under the requirements of full inspection of PE valve products

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