Leak Detection
Overview
Pressurised fluid is a positive method to check for internal and external leaks on components. Generally, a component is flushed with fluid to ensure there is no air trapped. It is then pressurised to the required test pressure and the leak check started. Three of the methods we use most commonly for leak detection is present are Pressure Change, Flow Measurement and Vision Systems.
Leak Detection Specifications:
| Test Pressure: | Up to 3000 bar |
| Temperature Range: | Ambient to 60°C depending on the type of test but could be significantly higher |
| Flow Range: | Measurable up to 20 cc/min |
| Cycle Time: | From 10 seconds |
| Evaluation Criteria: | Pressure decay over time, Timed pressure drop, Measured flow, Blob growth |
Leak Detection through Pressure Change
Leak detection through pressure change may be used for all forms of leak check but is especially useful for measuring the leak between internal mating surfaces. It is very well suited to the detection of small leaks due to its sensitivity. When using pressure change to detect a leak, either a pressure rise or decay is monitored.
Pressure Decay
One side of the mating face is pressurised and then isolated thus creating a chamber containing a fixed pressure. At the start of the test the pressure in the chamber is measured and recorded. After a set time the pressure in the chamber is sampled and the pressure drop calculated and converted to a leak rate. This value is then used to determine if the leak is within acceptable limits.
Pressure Rise
A seal is formed around both sides of the leak interface and one side pressurised. At the start of the test the pressure in the un-pressurised chamber is measured and recorded. After a set time the pressure in the chamber is sampled and the increase in pressure calculated. This value is used to determine if the leak is within acceptable limits.
Leak Detection through Flow Measurement
Where leak rates are more readily visible to commercially supplied equipment , it may be possible to measure it using the appropriate flow meter. One side of the leak interface is pressurised to the test pressure while on the other side is a collection chamber and path to the flow meter. When a Leak occurs, the flow is measured by the flow meter and the leak quantified.
FP-2200 High Pressure Test Machine
Click here for more information on the FP-2200 High Pressure Test Machine
Leak Detection with a Vision System
With applications where it is difficult or impractical to form
seal around the leak interface, it may be possible to use a vision
system for leak detection. This is generally only possible if the
leak manifests itself on an external surface of the component. This
method may also be used to determine the leakage rate if required.
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Principle
The component to be tested is pressurised. When the test pressure has been achieved the camera captures an image of the component and measures the number of foreground pixels in the area of interest. Throughout the test the camera continually acquires images and records the number of foreground pixels. At the end of the test various methods can be used to analyse the data from the images and determine if a leak is present.
Click here for general information on our vision system capabilities