Sealing performance under cryogenic temperatures should be a consideration in the development of a cryogenic valve for use in cryogenic engineering. In the present work, a cryogen-free leak detection system at 20 K to conduct leakage testing of cryogenic valves was developed. The experimental system was composed of a cooling system, a leak detection system, and a PLC (Programmable Logic Controller) system. Compared with the traditional cryogenic leak detection systems, this system using the GM cryocooler instead of cryogen is beneficial for the application for its low operating cost, simple structure, and safe handling. Five valves can be installed simultaneously and tested in sequence. The helium mass spectrometer leak detector is used for its sensitive response and high precision. The reliability of this system was verified by testing the leak rate of the system itself. Three high-pressure cryogenic solenoid valves were tested using helium gas under the pressure varied from approximately 2.5 bar to 80 bar and at both room temperature (300 K) and liquid hydrogen temperature (20 K). The tested valves can be cooled from room temperature to 18 K within 6 h. The test results of the internal leakage rate and the external leakage rate of the samples were discussed. This system will aid in the inspection of many critical cryogenic components such as liquid oxygen and liquid hydrogen valve assemblies for which leakage may lead to serious consequences.

在开发用于低温工程的低温阀时，应考虑低温下的密封性能。在目前的工作中，开发了一种在 20 K 下进行低温阀门泄漏测试的无冷冻剂泄漏检测系统。实验系统由冷却系统、泄漏检测系统和PLC（可编程逻辑控制器）系统组成。与传统的低温检漏系统相比，该系统使用GM低温冷却器代替致冷剂，运行成本低，结构简单，操作安全，有利于应用。可同时安装五个阀门，依次测试。采用氦质谱检漏仪，响应灵敏，精度高。该系统的可靠性是通过测试系统本身的泄漏率来验证的。三个高压低温电磁阀在室温 (300 K) 和液氢温度 (20 K) 下使用氦气进行了测试，压力从大约 2.5 巴到 80 巴不等。被测试的阀门可以在 6 小时内从室温冷却到 18 K。讨论了样品的内漏率和外漏率的测试结果。该系统将有助于检查许多关键的低温组件，例如液氧和液氢阀组件，如果泄漏可能会导致严重后果。5 bar 至 80 bar，在室温 (300 K) 和液氢温度 (20 K) 下。被测试的阀门可以在 6 小时内从室温冷却到 18 K。讨论了样品的内漏率和外漏率的测试结果。该系统将有助于检查许多关键的低温部件，例如液氧和液氢阀组件，这些部件的泄漏可能导致严重后果。5 bar 至 80 bar，在室温 (300 K) 和液氢温度 (20 K) 下。被测试的阀门可以在 6 小时内从室温冷却到 18 K。讨论了样品的内漏率和外漏率的测试结果。该系统将有助于检查许多关键的低温部件，例如液氧和液氢阀组件，这些部件的泄漏可能导致严重后果。