How to Buy a Leak Tester

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What You Should Know Before Buying Leak Test Equipment

Leak testing might appear simple and straightforward; however, finding a leak testing system best suited to your application can be deceivingly complex. This guide outlines what you need to know and the questions you should ask before buying a leak tester.


What is an Automatic Leak Tester?

Automatic leak testers perform tests without operator attention or interpretation.  Today’s high manufacturing standards demand sophisticated product testing.

Typical leak testing requires:

  • Specialized testing techniques
  • Various test pressures or vacuum levels
  • Multiple programs for various parts to be tested
  • Multiple testing either sequentially or simultaneously

A complete automatic cycle performs one or multiple tests from start to finish displaying quantitative results with accept and reject status. Accept and reject limits are programmable.

Common leak tester types:

  • Flow testers
  • Differential pressure decay leak testers
  • Pressure-decay and vacuum-decay leak testers

Automatic production leak testers typically perform leak tests in 0.2 seconds to 30 seconds. These testers easily communicate with programmable logic controllers (PLCs).

Common features:

  • Store test data
  • Monitor testing trends
  • Have maintenance programs
  • Change test programs automatically
  • Compensate for temperature changes
  • Automatically compensate and calibrate
  • Offer alarms for out-of-calibration conditions
  • Provide multiple station and multiple pressure
  • capability

What Does My Supplier Need From Me?

If you have testing parameters, provide them to your supplier. These facts will be important to your supplier:

  • Test volume
  • Part material
  • Reject leak rate
  • Test pressure
  • Test part description
  • Production rate
  • Part numbers of all items to be tested

If test parameters are not available, explain your application and challenges to your leak test supplier. Your supplier should have years of application experience to help you set parameters and select a system that’s right for your application.

For a new product, certain variables should be considered when setting leak test specifications. Answers to these questions will be helpful:

  • Working pressure of the product
  • Type of liquid or gas used in the product
  • How your product is used in the marketplace
  • Material from which the product is constructed
  • Whether the seal must prevent liquid or gas leakage
  • Consequences of leakage or improper flow, such as:

    • Cost to the user
    • Product malfunction
    • Product deterioration
    • Possible fire or explosion
    • Frustration or inconvenience
    • Harm to people or surroundings
    • Unsightly or displeasing environment

What About System Flexibility?

Without a doubt, one of the most important considerations in buying a leak tester is flexibility— one or two great features do not make a reliable leak test system.

Initially there may be a tendency to think you only need a go, no-go tester. Later on, however, you will realize the importance of qualifying test results. In the future, you might have specification changes, new products, or product variations that will require different types of testing. As your requirements change and increase, you will recognize needs for solid software maintenance and documentation, good manuals, and training support provided without hidden charges.

In the not-too-distant future, you might need data collection, active statistical analysis, LAN capability, bar code reading, temperature compensation, or other analog inputs. Experienced users have long recognized the need for flexibility built into well-designed leak testers. Flexibility is added to well-designed leak and flow testers for good reason. Although built-in flexibility may increase initial cost, flexibility has potential to save considerable amounts of time and money over the system’s lifetime.

Investigate what experienced users of leak testers buy. Experienced users insist on flexibility for many sound reasons.


What Should I Look For In A Supplier?

Be sure you select a leak tester supplier who has diverse experience and offers leak testing techniques that exactly match your application and requirement. Be cautious of suppliers who push one or two test types and must sell those as “the best way.” At a minimum, your leak tester supplier should offer and support a wide variety of test techniques, including:

❊Most common because of ruggedness and simplicity. With these techniques available, your supplier can honestly evaluate your requirements and recommend ideal techniques for your specific applications. Remember, when you purchase a quality product from a qualified and trusted supplier, you are provided with security and guaranteed performance. Look for quality registrations such as:

  •  ISO 9001
  • CSA (Canadian Standards)
  • CE MARK (European requirement)

These registrations help ensure additional overall quality, documentation, and validated software.


Are Resolution and Sensitivity Important?

Sensitivity and resolution should be among your major considerations when purchasing a leak tester. But they should be reviewed in the light of knowledge. Be sure you consider a complete system as well as long-term repeatability and stability of the test instrument.



When evaluating leak testers, you might see resolution claims such as .0001 psi or better. Be aware this resolution could merely reference analog-to-digital converters operating under ideal conditions, without noise, and without connection to the real world. While raw resolution numbers might be true, they are often not usable figures. To determine usable resolution, it is important to consider the entire system: electronics, sensors, pneumatic components, and the environment in which the test system will be used. Only then will you see the true picture of system resolution.



When you hear claims such as .01 cubic centimeters per minute leak sensitivity, be skeptical. While that sensitivity might be achievable, it might only be achievable in a few applications. As with resolution, the true testing sensitivity depends on the total system, including your part and test specifications. Purchasing a leak tester based on exaggerated claims of resolution and sensitivity can be a costly mistake.


What About Price?

You should never buy a leak tester based solely on price. Many factors should be considered besides initial cost. If you buy on price alone, you should also budget additional time and money for potential failure and on-going problems. If you can afford to do this, you can probably afford to purchase a quality leak tester from the beginning. For example, say you save several thousand dollars on your leak test machine’s initial purchase, this seemingly large savings can rapidly cost you in:

  • No local support
  • Poor performance
  • No telephone support
  • Extra cost for training
  • Non-repeatable results
  • Continuous breakdowns
  • Poor or inadequate manuals
  • Inadequate application support
  • No emergency parts availability
  • Extra cost for installation assistance
  • Lack of flexibility for changing needs
  • Calibration failures and product recall
  • Poor software maintenance and documentation

You cannot analyze tester cost by the formula that lower purchase price equals lower cost. Always consider the long-term value you will receive over years of ownership, and your partnership with a successful and innovative supplier.


Uson’s experts can help you select the best tester for the job.

As leaders in the industry, Uson continues to provide the highest level of leak testing equipment and solutions for medical, automotive, electric vehicle battery, industrial and packaging industries.  Our team of experts have assisted customers with thousands of applications allowing them to meet and exceed their production and quality standards.

We offer a variety of flexible, highly-accurate, automatic, air leak  and flow testing equipment to meet any testing and quality requirement.

If you’re in need of expert guidance on what test method and equipment is the best option for your project, the team at Uson can help.  Let’s talk about your next project!

Get reliable and accurate test results.


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