Designing a Reliable Leak Test for an IP68-rated Component

Designing an accurate, reliable leak test can be challenging—especially when you need to comply with strict industry standards. These standards vary, but could require that you test your products to a certain leak rate, pressure endurance, etc. The accuracy and reliability of these leak test results can be of the utmost importance to the part’s safe and intended use in the field.

So, what happens when you can’t seem to reliably leak test to your required specifications?

A manufacturer of water meters recently approached innomatec with this problem. They needed to test to a very low leak rate (0.3 ml/min) to comply with IP68 standards for their product. However, their existing leak tester couldn’t perform the stabilization required to reliably, repeatably meet the leak rate. This caused unacceptable uncertainty in their test results.

innomatec investigated their application and designed a new, innovative solution using the flexibility of the LTC-802 leak tester to ensure an accurate, reliable leak test and the highest product quality that complied with their required industry standards. Learn more about the new solution, below.

Designing an accurate, reliable leak test to comply with stringent quality standards

Given the nature of their use in the field, water meters must be highly leak-tight and reliable. The manufacturer set their leak rate to comply with IP68 standards, an ingress protection (IP) standard dictating a high level of water- and dust-tightness. A dependable leak test for this application requires stability and accuracy—both of which they were lacking in their previous leak test solution and instrumentation.

The challenge was that the leak test solution needed to be able to test the very small chamber of the water meter to a very low leak rate of 0.3 ml/min. In this case, accomplishing this level of control and reaching stabilization without extending cycle time can be difficult—but the leak test experts at innomatec were able to solve the problem.

innomatec designed an innovative solution using the LTC-802 that greatly reduced the volume of air required to do the test—nearly 0 ml, with a fill time of 1 sec. This cut down on the volume of air and the stabilization time required for the test, which made a big difference in achieving a reliable measurement at such a low leak rate (0.3 ml/min), without extending cycle time.

The LTC-802 was configured to perform a two-step leak test to ensure an accurate result:

1. First, the part was leak tested using the closed component method (or dosing method) to quickly identify any large, rough leaks. During this test, the part is filled with a controlled volume. With this known, controlled volume, a defined pressure ratio is expected. If the instrument detects an incorrect pressure change, this signifies a leak and the test ends with a major leak error. The part is then removed from production before moving to the next step.
2. If the part passed the first step, the pressure is stabilized and the second step begins. This is a pressure drop test (using the pressure differential method) to accurately test the part to the specified leak rate of 3 ml/min. During this test, the pressure inside the part is measured over a set period of time and the measured pressure change is output as a leakage rate, identifying whether it is within the allowable specifications of a quality part.  

Key components of the leak test solution

There were a few key factors that levered the flexibility of the LTC-802 and the innovative approach of the innomatec team that made this solution possible:

• Superior test stability and accuracy: innomatec’s LTC-802 is a high-precision leak tester, easily optimized for the resolution and operating range of the part being tested. It delivered the superior measurement system control required for this type of challenging leak test application.
• Innovative test design: innomatec is passionate about finding solutions to your leak test challenges. Using an innovative approach, innomatec was able to design a leak test solution that greatly reduced the distance between the leak test computer and the device under test to reach the low volume and low leak rate required for this application.

• Future-proof design: While the current design was to be manually loaded, the manufacturer also wanted the flexibility to implement a robotic loader in the future. innomatec happily obliged this request, designing the machine with hydraulic cylinders to accommodate future needs of the machine.
• Data communication: innomatec’s LTC-802 also allowed the manufacturer to easily record their processing data to ensure product quality, delivering their test results to their PLC through PROFINET.

Are you having trouble meeting your leak test specifications? innomatec can help!

If you’re struggling with the performance of your leak test, innomatec can help! innomatec has over 40 years’ experience helping top manufacturers across the globe design and improve their leak tests for the most accurate, reliable results.

Having trouble with your leak test? Contact the experts at innomatec.