Get the Total Guide to Leak Test Methods
When designing a leak test for a new product, manufacturers have a wide variety of choices in test approach and method. Perhaps the simplest approach and method is underwater leak testing, or “bubble testing”. While this can be a good option for some applications, many applications will require a more complex automated solution. While both methods can detect leaks, their suitability varies depending on desired leak rate precision, product design, product application, production goals, regulatory compliance requirements, and more.
In this blog, we’ll explore the differences between these methods, and how to choose the right approach for your manufacturing needs.
What is underwater leak testing?
An underwater visual inspection leak test is the most simple and perhaps the most common leak test method. During the underwater leak test, a gas-filled test specimen is placed under water or partially wetted with water. Bubbles are then visually monitored and measured by the test operator, identifying any leak sites on the part.
innomatec test bench designed for underwater leak testing.
As the part is largely removed from environmental conditions such as temperature, drafts, vibrations, etc., this can allow for the detection of very small leakages under longer observation time—sometimes even smaller than with pressure change measurement methods— to a detectable leakage rate of >0.05 cm³/min 1 bubble Ø 1 mm/4.2 sec (volume and pressure dependent; see leak rate equivalency chart below). Even temperature-treated, unstable and very large components can be tested for leaks under water, sometimes at very high test pressures.
Calculation of the leakage rate based on air bubbles under water.
However, this method can be limiting. It is ideal for basic leak detection and location applications, with the requirement that the parts or components can get wet (submerged in water). Depending on your parts and the leak rate accuracy you require, you may be better suited to an air leak test method, or helium / tracer gas leak test method.
When is it recommended to use an automated leak test method instead?
While underwater leak testing can be effective for some leak applications, it relies heavily on operator observation, making the results largely subjective, varying according to factory and shift, and making quantitative leak rate determination difficult. As result, underwater leak testing is less suited for high-volume, and/or highly-regulated manufacturing environments.
Transitioning from underwater leak testing to automated leak testing methods is often driven by the need for greater precision, efficiency, and scalability. If your production line is experiencing increased output demands, stricter quality standards, or requires the detection of micro-leaks that are invisible or difficult to measure accurately with the human eye, it may be time to consider automation.
Automated systems provide consistent, repeatable results and can integrate seamlessly into high-volume manufacturing processes, reducing human error and costs associated with faulty parts. Additionally, if your products must meet strict industry regulations or customer specifications, automated leak testing’s enhanced accuracy and production data recording capabilities offer a significant advantage. Evaluating your production goals, quality requirements, and budget can help determine when the shift to automation is the right decision.
How to choose the best leak test method for your application
Characteristics such as the type of part, application of part, component size and volume, operational reliability/failure safety, integration into the running process and many more, must be considered in the selection of the ideal measuring method and leak tester for your application. To learn more about the different leak test methods and how to choose which is best for your application, contact us. You can also download our free "Total Guide to Leak Test Methods”.
