In high-stakes manufacturing environments—like medical device production, fluid systems, and electronic enclosures—verifying a product’s integrity is non-negotiable. One of the most established and reliable ways to do that is through pressure decay leak testing. This non-destructive method is valued for its simplicity, sensitivity, and adaptability across a wide range of applications. In this article, we’ll break down how pressure decay testing works, what factors influence its performance, and how manufacturers use it to ensure airtight quality—day after day.
What Is Pressure Decay Leak Testing?
Pressure decay testing measures whether a sealed component is leaking by pressurizing it with air, isolating it from the pressure source, and observing any drop in pressure over time. If the pressure decreases beyond an allowable limit, a leak is present. This method is most effective for sealed parts with an access port, making it a common choice in industries that demand both precision and repeatability.
How the Pressure Decay Process Works
The core of pressure decay testing—particularly as implemented by Zaxis leak testers—follows a structured four-stage process. This sequence is designed to deliver precise, repeatable results with minimal operator input. Here’s how it works, step by step:
1. FILL: The part is connected to a Zaxis tester using a fixture or fitting. Compressed air is introduced until the part reaches the programmed test pressure. The FILL stage is optimized for speed and control, using accurate pressure regulation to ensure consistency from part to part.
2. SETTLE: Once pressurized, the part is isolated from the air source. During this brief pause, internal pressure stabilizes—accounting for effects like part flex or thermal shifts. Zaxis testers allow this SETTLE period to be configured based on the characteristics of the part, helping reduce false failures.
3. TEST: During the TEST phase, a high-resolution sensor monitors the internal pressure. If the pressure decays beyond a specified limit, a leak is indicated. Zaxis systems can detect incredibly small pressure drops—down to 0.00001 PSI—making them ideal for sensitive components like catheters or implantable devices.
4. VENT: At the end of the test, any remaining pressure is safely vented to the atmosphere. This step resets the system for the next test cycle, keeping production flowing efficiently. In Zaxis systems, the VENT stage is fully automated for fast cycle times and high throughput.
Factors That Influence Test Sensitivity
To get the most from pressure decay testing, it’s important to understand what affects sensitivity and reliability:
- Part Volume: Larger internal volumes require longer test times for accurate results, while smaller parts can be tested more quickly.
- Test Pressure: Higher pressures may improve leak visibility but must be compatible with the material and function of the part.
- Cycle Time: Increasing the duration of the fill or test stages can improve sensitivity but may reduce throughput.
- Sensor Accuracy: The finer the resolution of your pressure sensor, the smaller the leak you can detect.
Balancing these factors is key to creating an optimized test profile—and Zaxis systems offer parameter customization to fine-tune each stage.
Where Pressure Decay Testing Shines
This method is especially useful when testing:
- Medical devices
(e.g. catheters, IV sets, infusion bags, implantable devices)
- Plastic and elastomeric components
(e.g. connectors, tubing, seals)
- Sealed enclosures and sensors
(e.g. fluid meters, electronic housings)
Its non-destructive nature, short cycle times, and broad applicability make it a go-to solution for manufacturers requiring in-line or batch leak testing.
For parts with very large volumes or extremely tight leak specifications, differential pressure testing—also supported by Zaxis—may be a better fit.
Real-World Benefits of Pressure Decay Testing
Here’s why manufacturers continue to rely on pressure decay:
- Accurate – Capable of detecting extremely small pressure drops
- Repeatable – Consistent results even across long production runs
- Efficient – Especially effective for small parts with fast test cycles
- Scalable – Works equally well for R&D, pilot lines, or full-scale production
Zaxis systems integrate seamlessly into various production setups, whether standalone at a bench or embedded in automated lines, and offer data logging for traceability and compliance.
Final Thoughts
Pressure decay testing remains a go-to method for manufacturers who need fast, repeatable, and sensitive leak detection. Its ease of use and repeatability make it ideal for many types of components—especially where airtight performance is critical. Understanding how the method works and what affects its performance can help engineers and quality managers fine-tune their processes and select the right tools for the job.
Need help identifying the best leak testing method for your part? An experienced testing partner can help you navigate options like pressure decay, differential, vacuum, or mass flow testing based on your specific needs. Contact sales@zaxisinc.com today!
