Maintaining control over environmental conditions is essential for achieving accurate and repeatable leak test results, yet it is often overlooked. Fluctuations in atmospheric pressure can significantly influence pressure-based leak detection methods, leading to unstable and skewed measurements, and even false failures or false passes.
Understanding how ambient pressure interacts with your leak test system—and implementing strategies to monitor, compensate for, and stabilize it—is critical for ensuring reliable performance. By implementing specific process designs, manufacturers can improve the consistency of their tests and reduce measurement uncertainty.
What is ambient pressure?
Ambient pressure refers to the atmospheric pressure in the environment where a test is being performed. On a factory floor, ambient pressure is rarely perfectly stable. Daily weather changes, door openings, compressed air surges, and temperature shifts can all introduce small but measurable pressure variations.
How does ambient pressure affect leak testing?
In pressure-based leak detection methods—such as pressure decay, differential pressure, or mass flow testing—the measurement system often references ambient pressure either directly or indirectly. Any change in the surrounding atmospheric pressure can influence:
The measured pressure inside the test part
For example, if atmospheric pressure drops during a test cycle, the pressure differential between the inside of the test part and the surrounding environment increases slightly. As a result, the leak rates of existing leaks in the component may change slightly. This can become a problem, especially in highly sensitive applications with long cycle times.
If you are testing large components like battery trays or fuel tanks, thin materials like plastic bags, and/or testing at low pressures (i.e. test pressures of just a few mbar), then ambient pressure changes can have a huge impact on test results. Even a small difference of just a few mbar can impact the measurement tremendously.
How can manufacturers control for ambient pressure?
Machine and fixture design becomes very important in controlling for these factors. The key is to design the test in such a way that it absorbs the environment or protects the part from the environment around the machine for the most reliable, repeatable measurement results.
Controlling for ambient pressure in leak testing starts with measurement and compensation. Incorporating a barometric reference sensor into the test system allows real-time monitoring of atmospheric fluctuations so the test instrument can identify and/or correct for changes during the test cycle. In addition, isolating the test station from drafts, HVAC and high airflow areas helps reduce short-term pressure disturbances and seals off the resulting airflows.
For high-precision applications, maintaining a stable, climate-controlled test environment and allowing parts to acclimate before testing further improves repeatability. By combining environmental stability with active pressure compensation, manufacturers can minimize ambient influence and ensure consistent, reliable leak test results.
Need help controlling ambient pressure during your leak test? Contact us!
If you are having trouble refining your leak testing process, the innomatec team is here to help! Our leak test experts will analyze your production area to identify any environmental factors that could impact a leak test and provide recommendations accordingly.
innomatec is uniquely positioned with the in-house experience and capabilities to deliver on any leak test requirement, including industry-leading instrumentation for all leak test methods, pressure-tight connec® seals and connectors, and full leak test machine design and development. Contact us to discuss your leak test today!
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