While vacuum decay is a popular leak testing option, it is not ideal for empty containers. Pressure decay is a great alternative to allow defects to be identified quickly, all while maintaining container integrity.
Testing empty containers for leaks and defects is the most effective way to ensure product quality. However, being able to identify such defects efficiently is essential for container manufacturers.
While vacuum decay testing is popular, it is not ideal for empty containers. Vacuum decay can often cause empty bottles to collapse during the test. This is why pressure decay leak testing with ALPS Inspection is the best way to identify defects in empty containers, all while maintaining container integrity.
In this blog, we will discuss what you need to know about pressure decay testing, including what it is, how it differs from vacuum decay testing, and why every plastic bottle converter should consider implementing a pressure decay leak detector into their manufacturing line.
What Is Pressure Decay Leak Testing?
Pressure decay leak testing is a non-destructive quality control method used to detect leaks and ensure the integrity of containers, such as bottles, jars, or other hollow products. In this process, the container is filled with pressurized air, and the system monitors the pressure over a specified period. If there is a drop in pressure beyond a set threshold, it indicates the presence of a leak.
This testing method is especially effective for empty containers. With pressure decay, the empty container will not collapse during testing, which may occur with alternative methods like vacuum decay testing. Pressure decay testing provides accurate and reliable results, ensuring every container meets strict quality standards while maintaining its shape and integrity. Pressure decay leak testing is widely used in industries like food and beverage, pharmaceuticals, industrial, and more.
ALPS Inspection offers in-line pressure decay leak testers for every industry and application. Our goal is to ensure every container that reaches your customer is of the highest quality. Learn more!
Pressure Decay Leak Test vs. Vacuum Decay
When it comes to container leak testing, choosing between pressure decay and vacuum decay methods depends on your specific application and container type.
Are you testing filled containers or empty containers? If you are testing empty containers that are not required to have a vacuum seal, then a pressure decay leak test is the most efficient method. Pressure decay is also beneficial in applications where the lack of container stability allows the possibility of an empty container to collapse during testing.
If you’re testing a filled container or one that requires a vacuum seal, then a vacuum decay test may be your best solution. Vacuum decay testing is a non-destructive test that detects leaks in nonporous, rigid or flexible packages. This method ensures that containers that contain items such as food or beverage are safe from possible container leakage after being filled and sealed.
Explore our full line of pressure decay leak testing systems
How Does a Pressure Decay Leak Test Work?
A typical pressure decay leak tester is installed downstream of the blow molder on the line and uses a three-step process for empty bottle inspection:
- As an empty container enters the leak tester, a probe creates a leak-tight seal at the opening. The tester fills the container to the desired pressure and monitors it. If the target pressure isn't reached within a set time, the container is marked as a ‘reject’ due to a gross leak. If the pressure is achieved, the tester records the peak value and moves to step 2.
- The tester measures the pressure drop over an initial time period (T1) and calculates the percentage loss. A slight loss is normal, but if the percentage exceeds a set limit, the container is categorized as a ‘reject.’ Otherwise, the test continues.
- The percentage drop from T1 pressure is measured against another pre-set limit (T2) , ensuring the stability of the bottle. Containers exceeding the pressure loss limit are rejected, while those below it are deemed ‘good.’ This step ensures the detection of even the smallest leaks.
The three steps of the pressure decay testing process.
Not only does ALPS pressure decay testing measure peak pressure, but also changes in pressure over time. This could indicate a small leak that may not be caught with 1-step pressure decay testing.
Take a deeper dive into the three steps of pressure decay testing.
“Rules of Thumb” For Pressure Decay Testing
There are a few things you need to keep in mind when pressure decay testing:
- Sensitivity increases as you increase test time. The longer you test a bottle, the more time the system has available to detect pressure drops.
- Hole size detection depends on the sensitivity of the unit. Other pressure decay testers can miss holes up to 1mm (larger than a paper clip). While ALPS units can detect much smaller holes.
- Some pressure drop is normal even in good bottles. As containers may stretch under pressure slightly while the air stabilizes after pressurization.
- It takes longer to detect leaks in large bottles and containers than smaller units, due to the increased volume of the product.
It is important to try to control temperature variations on the line as much as possible. This will help ensure proper consistency with pressure decay testing equipment.
The ALPS Point of Difference in Pressure Decay Testing — What Makes Us Stand Out?
Engineered for precision, ALPS leak testers use test pressures as low as 20 millibars – up to 5 times less than other testers.
Using low pressure during testing reduces the likelihood of bottle deformation, ensuring better test accuracy and faster test times by allowing us to reach the desired pressure quickly.
In turn, this enables our testers to be ideal for detecting seal surface defects. Seal surface defects are often found in HDPE and PET containers.
Want more insight into the different types of plastic container defects and the best troubleshooting methods? Click here!
The Benefits of Choosing ALPS Inspection In-Line Pressure Decay Leak Testing Solutions
First and foremost, ALPS in-line leak testing ensures that products will not leak out of the container. And that oxygen, moisture, and other contaminants will not get in. In turn, this helps maintain product quality and integrity.
Not only that, but our pressure decay leak detection systems tests each bottle as part of the manufacturing process. This provides much better results compared to random sampling, which does not guarantee defect detection.
You also enjoy better monitoring of the blow molding process. Issues with leaks can be an early warning sign that one or more of your pieces of manufacturing equipment may be faulty or may require maintenance and servicing.
Together, these benefits help you protect your inventory and prevent costly returns of faulty products.
Discover why leak testing is vital in the plastics industry in this blog post.
Contact Us Now to Learn More – And Get Started Right Away
If you are ready to invest in pressure decay testing technology from ALPS Inspection, do not wait. Contact us or give us a call at 1 (800) 325-8717 to learn more. See how you can implement this technology into your manufacturing line.
Not ready to call us yet? Click on our Product Selector tool below to see which in-line leak testing solution will best fit your manufacturing needs!
