Leak testing lingo – a glossary
Do you know your vacuum leak test from your chamber leak test? Your pressure decay leak testing equipment from your mass flow leak testing process?
If talk of bubble leak testing seems a load of babble, or even if you just fancy a recap. Check out the Industrial Physics’ glossary of leak testing lingo.
A leaking package or product can mean product failure. Which can hurt your reputation, prove costly and even damage consumer health.
Leaks of liquid or gas derive from defects – be that a crack, a hole, or a failed seal.. As a packaging maker or user it’s up to you – or a regulatory body – to decide how large a hole must be to cause a leak test failure.
The process of quantifying whether an object or system is functioning within a specific leak limit is known as leak testing.
Pressure decay leak testing
Decay describes the difference in pressure from a starting state of complete pressurization to the pressure at the end of a leak test cycle. Pressure decay leak testing is a fast, accurate leak testing process.
You simply fill your package or product with air, remove the supply pressure and measure the pressure release. If the decay (loss) of the pressure is different to what you expect then this indicates a leak.
The chamber leak test
A chamber leak test will help you to find leaks in sealed packages and devices. If your test object doesn’t include an opening for filling, it’s a sensible leak testing method to adopt.
The process looks like this. Your test object is placed in a sealed chamber which is pressurized with a measured volume of air. Once you reach the desired pressure point, the test begins. It’s a straightforward approach: if the pressure holds, your product passes; if the pressure drops, your product fails as a leak has been detected.
Mass flow leak testing
Mass flow leak testing allows you to measure any leakage directly. The flow of air moving from the reference volume into the package or test item is read. It’s a quick leak testing method that uses the intrinsic properties of air to measure the amount of it escaping from a closed system.
Your package or test part is pressurized, but you keep it connected to the supply pressure. Once you reach a point of equilibrium and the pressure is stabilized – you’ll know that the gas flowing in from the supply is equal to the total leakage of gas flowing out.
A pressure regulator establishes the testing pressure, and then the sensor records any movement of air out of the test system. Which is how it enables you to get a direct leak test result.
Mass flow testing can also be used to identify obstructions – known as occlusions. So it’s useful for medical device leak testing for items like catheters or IV bags.
The bubble leak test
The bubble leak test is a simple, cost-effective method of detecting and assessing leak rate .
It follows the ASTM F2096 standard. You take the part under test, submerge it in water, gently pressurize and visually observe how quickly any bubbles escape to determine the leak rate .
It’s a simple calculation – you measure the number of bubbles and divide this figure by the measuring time. Sounds easy right? However, if the test part has a high pressure then it can burst or explode. It’s also time consuming, destructive and not the most sensitive of tests…especially if the operator is not on their best form!
The blister leak test
Pharmaceutical companies that use blister packs for tablets must ensure that moisture does not get in through miniscule gaps over time. This can alter the appearance and weight of the medicine or even harm the efficacy of the treatment.
The simple and effective blue dye leak test is the most common type of process for leak testing blister packages. This blister leak test involves putting the packaging into a container of methylene blue dye. A vacuum is applied and the container is inspected visually – or using spectrophotometry – to see if there has been an ingress of the dye. It’s a qualitative and destructive form of leak test.
The force decay leak test
You can’t force your flexible packaging to perform under pressure…but you can force decay leak test it. Which is almost as good!
It’s a non-destructive leak test that can help you to identify flexible package integrity issues such as weak seals. It works best for packages with a low headspace.
You place the package in a vacuum chamber between two plates – one of these is connected to a force sensor. As the package expands it puts pressure on the sensor. The vacuum levels are monitored during the test – if a decay in the expansion force or vacuum level is recorded…your package fails the test.
It’s a non-destructive leak test and several packages can be tested per cycle.
We’re fluent in leak testing
We trust that our glossary of leak testing lingo plugged any unacceptable gaps in your basic leak test knowledge. At Industrial Physics we walk our talk and design the best leak testing machines on the market. So if we’re talking your language then check out our product range and get in touch today!