Leak Detection During Vacuum System Installation

Vacuum systems have strict requirements on sealing, so leak detection is required at all stages of vacuum system design. The installation and testing especially need leak detection.


During the installation and testing of the vacuum system, checking and ensuring the tightness of the connection parts is the key point of the leak detection work. The premise is that the air tightness of the welding seam of the vacuum equipment has passed the leak detection at the processing stage, so as to avoid multiple leak detection at the same time, leading to increased workload and difficulty. For large and complex vacuum equipment, it is best to use segmented leak detection. After each stage is completed, a leak detection is performed on the corresponding connection parts and welds, and the next step is performed after the requirements are met.


Specifically, the following aspects should be paid attention to:


First, understand the structural composition and assembly process of the equipment to be inspected. Master the requirements of the equipment and identify the key suspicious parts that need to be leaked. 


Secondly, according to the requirements of the maximum allowable leak rate allowed by the actual application of the vacuum system and whether it is necessary to find the specific location of the leak hole, proceeding from the principles of economy, speed and reliability, correctly select the leak detection method or instrument, and prepare the leak detection method or instrument and develop practical leak detection procedures. 


Third, carry out the cleaning work on the inspected parts, take out welding slag, grease, etc., and then clean them according to the requirements of vacuum sanitary conditions, and then dry them. For small devices with high requirements, they can be baked in a vacuum oven after cleaning. This is mainly to prevent leaks from being blocked by dirt, oil, organic solutions, etc., and to protect the leak detector. 


Fourth, after the leak detection method and leak detection equipment are determined, it is necessary to calibrate the leak detection sensitivity and determine the leak detection time of the leak detection system. 


Fifth, if the vacuum leak detection method is used, in order to improve the sensitivity of the instrument, the test piece should be pumped to a higher vacuum as much as possible. 


Sixth, under the premise of meeting the requirements of the vacuum system, the leak detection method that is economical and available on site is preferred. 


Seventh, when using helium mass spectrometry leak detection equipment, for the tested parts that do not require high leak detection or have large leaks, try to use helium gas with a lower concentration for leak detection in the early stage of leak detection, and then conduct small leak detection to save helium. 


Eighth, the detected large leak should be repaired and blocked in time, and then the small leak should be detected. 


Ninth, the leaks detected and repaired need to be reviewed to ensure that the leak detection results meet the requirements. 


In addition to the leak detection work at each stage, the vacuum system should maintain a good daily leak detection habit in the application, and form a standard to ensure the good operation of the vacuum system.



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