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Leak testing method is a very known and important method using for leak detection in the industries. Leak test and leak detection using air decay, helium or water submerse methods. The choice of the detection method depends on which method is most appropriate for the system at hand. Leak testing methods each have their own sensitivity, expressed as the lowest leak rate the method can detect. Highly sensitive methods are required to test highly leak prone systems such as vacuum systems.
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What Is Leak Testing? Methods Of Leak Testing www.kryovess.com
What Is Leak Testing? Leak testing is the method of checking a structure for leaks. Leak testing can be achieved using a range of leak detection methods and is working to test for defects in products and to ensure the proper function and maintenance of industrial systems and pipelines. www.kryovess.com
Methods Of Leak Testing 1 Water immersion bubble test method 2 Soap solution bubble test 3 Pressure decay test 4 Vacuum decay test or Pressure rise test 5 Tracer gas leak testing : 1 Sniffing 2 Accumulation leak testing 3 Vacuum chamber inside-out leak testing 4 Outside-in leak testing www.kryovess.com
Water Immersion Bubble Test Method The Bubble Immersion leak test method is the simplest and lowest cost leak test method. It can be used on test parts that can be internally pressurized with air and will not be damaged by contact with water. This method, however, suffers from the disadvantage that an operator must pay close attention during the test to visually detect bubbles emitting from the part. Additionally, this method has no way of reliably calibrating the test because operators are typically instructed to reject a test part if bubbles are seen emanating from it. www.kryovess.com
Soap Solution Bubble Test Instead of submersing the part in water, the pressurized unit to be tested is sprayed with a soap solution and the operator is able to see the bubbles formed by gas escaping from where the leak is. Soap solutions are available in many different types. Some brands may have a spray applicator to quickly cover large areas of tubing in a short amount of time. www.kryovess.com
Pressure Decay Test Pressure decay is an older technology that has existed for many years. It is an indirect leak flow measurement with a leak rate based on decay rate and test pressure. Test volume is calculated for every set up. It is sometimes called “calibration.” Differential pressure decay offers a higher resolution and cost when compared to pressure decay. www.kryovess.com
Vacuum Decay Test Or Pressure Rise Test Pressure testing can be used to detect larger leaks requiring correction prior to the component undergoing a more sensitive, Mass Spectrometer/Leak Detector test. Unless there is significant time available, Pressure Decay is the least sensitive of all the techniques discussed here but does have a very valuable role to play in the production scenario. www.kryovess.com
Tracer Gas Leak Testing In the past several different tracer gases have been used to find leaks and to measure leak rates, for example Ammonia or halogen gases. But since the leak test method with the tracer gas helium and the detection of this gas with a mass spectrometer was developed, all other methods became less significant compared to the superior sensitivity of the helium method. www.kryovess.com
Types Tracer Gas Leak Testing 1 Sniffing 2 Accumulation leak testing 3 Vacuum chamber inside-out leak testing 4 Outside-in leak testing. www.kryovess.com
Sniffing Helium sniffing is a method of leak detection that uses helium as a tracer gas in combination with instrumentation that can detect presence of helium in the environment and more specifically an increase in helium due to a leaking part. www.kryovess.com
Accumulation Leak Testing Accumulation Tracer Gas Systems use the same instrumentation as Atmospheric Sniffing but use an enclosure to isolate the part from ambient background and contain the tracer gas. Accumulation Tracer Gas Systems provide an alternate type of tracer gas leak testing when atmospheric background is controlled. www.kryovess.com
Vacuum Chamber Inside-Out Leak Testing The component to be tested is pressurized with test trace gas, typically Helium, either pre-charged and inserted in a vacuum chamber or charged during evacuation. Any leak in the system will allow the trace gas to leak into the vacuum chamber where it will be detected by the leak detector. www.kryovess.com
Outside-in Leak Testing The component to be tested is connected to a vacuum pump and Leak Detector and evacuated. The part is held in a chamber or hood which is filled with a known Tracer Gas – typically Helium. The system (Leak Detector) then monitors for the ingress, hence the term Outside-In, of Tracer Gas to the part indicating the presence of a leak. This type of test is easily automated and, time permitting, can be more sensitive than sniffing. www.kryovess.com
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