Polyethylene valve sealing performance room temperature low pressure test method

Abstract

The invention provides a polyethylene valve sealing performance room temperature low pressure test method. A test stand self-contained closed-loop control system is utilized to perform automatic pressurization on a valve test cavity and a standard cylinder to achieve test standard pressure with indoor air acting as a test medium under the premise of confirming reliable sealing of the valve end surface and no leakage of the air passage of the test stand. Temperature and change of differential pressure of test air in the valve test cavity and the standard cylinder are detected synchronously by utilizing a temperature sensor and a differential pressure sensor, and all two-dimensional data in the time period of pressurization testing or the time period before leakage alarm are acquired and transmitted to a single-chip microcomputer to perform cross correlation analysis. Valve sealing performance judgment is given on the basis of a certain differential pressure drop gradient value within unit period of time according to the no leakage necessary and sufficient conditions that any points on a fitting curve of medium temperature difference and differential pressure at the same time axis have the same change of gradient, and temperature and pressure values of any time have a single proportional relationship. The method has no requirement for a constant temperature environment, and has the characteristics of being high in resolution and rapid 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...

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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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