Understanding leaks and leak testing in products and packages

Leak testing covers a range of techniques designed to check that the contents of your packages won’t leak out and stop environmental contaminants from sneaking in. 

It’s also used across a wide range of industries, from automotive to medical devices, to check the capability of products and their components to resist leaks of different gases and fluids. 

What is a leak?

Before we delve into the leak test types and the moisture and air leak testers that are available, let’s first determine – what is a leak?  

Simply put, a leak is a hole or path through which the contents of a package may escape, or through which ambient materials from the environment may enter. Look close enough, and you’ll find holes in everything because… everything leaks! Even if it’s the permeation of gas molecules through a metal or plastic, or atoms leaking through a lead shield, it’s just a matter of time.  

Leak testing is important to organizations working across a wide range of sectors. For companies working with environmentally toxic products, leak testing is an essential step to ensure they remain in the packages until opened! In the food and beverage sector, it’s of vital importance to control the ingression leaks of contaminant gasses and liquids that can affect everything from shelf life, to taste and even nutrition. 

The TME leak testing connection

Through TME, our specialist leak testing brand, we produce a wide range of leak testing devices, including bubble leak detectors and air leak testers, for all types of packages and purposes.  

These include the TME WORKER™ Leak and Flow Tester, an affordable, dependable tool for multipurpose leak testing. Other options we’d happily demonstrate to you include the TME Pressure Bubble Tester, a low pressure, controlled flow bubble tester, or the TME WORKER™ Integra – for reliable leak, flow and vacuum decay testing in one integrated process control tool. 

Common types of leak testing

Depending on the type of sample material or component that you’re inspecting, there are several different methods of leak testing available. The following two are the most commonly used when it comes to the leak testing of food and beverage packaging.   

Bubble testing: also known as dunk testing, is the most basic type of leak test. It relates to submerging and pressurizing a sample or component under water and then looking for gas bubbles. Compressed air is commonly used for bubble testing, and the part is tested at various pressures and time frames. The size and frequency of bubbles both signify the size of the leak.  

Sniffer testing with trace gas: for parts and systems with extremely low leak rate requirements, you can use tracer gas leak tests such as sniff leak testing, nitrogen purge leak testing, accumulation leak testing, and hard vacuum helium mass spec leak testing. 

How much leakage is too much?

As a packaging manufacturer or user, it’s up to you to decide how large a hole must be to cause a failure, and where that hole is likely to be located. Leak testing will help you with this. An accurate moisture or air leak tester will guide the selection of your raw materials, supporting both your research and development and quality control processes.  

In order to define how much leakage is too much leakage, and indeed, to measure leakage at all, we need to understand one basic relationship:  

leakage (or leak rate) = ∆V / ∆t

where V is the volume of the medium exiting or entering, and t is the time period during which you are measuring the change in volume.  Leak rate is therefore the volume of material (air, fluid etc.) that escapes from a closed or sealed containment in a predetermined amount of time. 

The price of “no leaks”

Once you have determined the size of the critical leak for your particular package, part or device, you can develop your test specifications and research the best test method to serve your needs. 

As you set your specifications, you’ll encounter wide bands around each method to accommodate the different instrument types and the fixturing required to implement the right leak test. There’s typically a cost involved in this quality control step. As you may expect, the greater the sensitivity you need, the higher the cost. When it’s important to your business that you can detect very low leak rates, then the higher cost of equipment can be justified.  

To give you an idea, the following graphic offers an estimate of the capital costs involved in the various types of leak testing. 

Read more in our leak testing whitepaper

Read more about the different types of leaks faced by manufacturers in various industries and how they relate to devices, products and packages in this extract from our whitepaper on leak, flow and package testing.  

Published by TME, our specialist leak testing brand, the paper includes lots of information, including tables of typical leak rates for a variety of medical and industrial products. It also provides information and guidance on how to make sure that your testing parameters are appropriate for the type of leak test you need to perform and the units of measure to use.  

If you have any questions about leak testing, our range of moisture or air leak testers, or any aspect of inspecting your food or beverage packaging – get in touch!