What you should know before buying leak testers
Leak testing may seem simple and straightforward, but finding the most suitable leak testing system for your application can be extremely complex. This guide tells you what you need to know and the questions you should ask yourself before buying a leak tester.
...
What is an automatic leak tester?
Automatic leak testers perform tests without the operator having to intervene or evaluate them. Today's high manufacturing standards require sophisticated product testing.
Typical leak tests require:
Specialised testing techniques
Different test pressures or vacuum levels
Multiple programmes for different parts to be tested
Multiple tests either sequentially or simultaneously
A complete automatic cycle runs one or more tests from start to finish and displays the quantitative results with acceptance and rejection status. Acceptance and rejection limits are programmable.
Common types of leak testers:
Flow testers
Differential pressure drop leak testers
Pressure decay and vacuum decay leak testers
Automatic leak testers for production typically perform leak tests in 0.2 seconds to 30 seconds. These testers can easily communicate with programmable logic controllers (PLCs).
Common features:
Storage of test data
Monitoring of test trends
Availability of maintenance programmes
Automatic change of test programmes
Compensation of temperature fluctuations
Automatic compensation and calibration
Provides alarms for out-of-calibration conditions
Provides multiple station and pressure
Capability
What does my supplier need from me?
If you have test parameters, provide them to your supplier. These facts will be important to your supplier:
Test volume
Material of the part
Leakage rate
Test pressure
Description of the test part
Production rate
Part numbers of all parts to be tested
If test parameters are not available, explain your application and problems to your leak testing supplier. Your supplier should have years of application experience to help you establish parameters and select a system suitable for your application.
For a new product, certain variables should be considered when establishing leak test specifications. Answers to these questions are helpful:
Operating 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 made
Whether the seal needs to prevent leakage of liquid or gas
Consequences of leakage or improper flow, such as:
Cost to the user
Malfunction of the product
Deterioration of the product
Possible fire or explosion
Frustration or inconvenience
Damage to persons or the environment
Unsightly or unpleasant environment
What about system flexibility?
One of the most important considerations when buying a leak tester is undoubtedly flexibility - one or two great features do not make a reliable leak testing system.
Initially, you may be inclined to think that all you need is a device to test whether it works or not. Later, however, you will realise how important it is to qualify the test results. In the future, you may have changes in specifications, new products or product variants that require different types of testing. As your requirements change and increase, you will realise that you need solid software maintenance and documentation, good manuals and training support with no hidden costs.
In the not-too-distant future, you may need data acquisition, active statistical analysis, LAN capability, barcode reading, temperature compensation or other analogue inputs. Experienced users have long recognised that a well-designed leak tester must be flexible. Flexibility is built into well-designed leak and flow testers for good reason. Although built-in flexibility can increase initial cost, it has the potential to save significant amounts of time and money over the life of the system.
Inquire about what experienced users of leak testers buy. Experienced users insist on flexibility for many good reasons.
What should I look for in a supplier?
Make sure you choose a leak testing equipment supplier that has a wide range of experience and offers leak testing procedures that fit your exact application and requirements. Be wary of suppliers who only offer one or two types of testing and have to sell it as "the best method". At a minimum, your leak test equipment provider should offer and support a wide range of testing techniques, including:
Mass flow
Pressure drop ❊
Vacuum drop ❊
Pressure rise
Tests on sealed components
Differential pressure drop
❊ Most widely used for their robustness and simplicity. With these procedures, your supplier can honestly evaluate your requirements and recommend the ideal procedures for your specific applications. Remember, when you buy a quality product from a qualified and trusted supplier, you get peace of mind and guaranteed performance. Look for quality certificates such as:
ISO 9001
CSA (Canadian standards)
CE Marking (European requirement)
These certifications ensure additional quality, documentation and tested software.
Are resolution and sensitivity important?
Sensitivity and resolution should be among the most important considerations when purchasing a leak tester. However, they should be reviewed in light of the level of knowledge. Look for a complete system as well as long-term repeatability and stability of the tester.
Resolution
When evaluating leak testers, resolution claims such as 0.0001 psi or better are often made. Note that this resolution could refer only to analogue-to-digital transducers operating under ideal conditions, with no noise and no connection to the real world. Raw resolution figures may be correct, but they are often not useful. To determine a usable resolution, the entire system must be considered: Electronics, sensors, pneumatic components and the environment in which the test system is used. Only then will you get a true picture of the system resolution.
Sensitivity
When you hear claims like 0.01 cubic centimetres per minute leak sensitivity, you should be sceptical. This sensitivity may be achievable, but only in a few applications. As with resolution, actual test sensitivity depends on the overall system, including your part and test specifications. Buying a leak tester based on exaggerated claims of resolution and sensitivity can be an expensive mistake.
What about price?
You should never buy a leak tester based on price alone. Many factors should be considered in addition to the initial cost. If you buy based on price alone, you should also factor in extra time and money for potential failures and ongoing problems. If you can afford it, you can probably afford to buy a high-quality leak tester from the start. For example, if you save several thousand dollars on the purchase of your leak tester, this seemingly large saving can quickly cost you dearly:
No on-site support
Poor performance
No telephone support
Additional costs for training
Non-repeatable results
Constant breakdowns
Poor or inadequate manuals
Inadequate application support
No availability of spare parts for emergencies
Additional costs for installation support
Lack of flexibility to meet changing requirements
Calibration failures and product recalls
Insufficient software maintenance and documentation
Tirron and Uson can help!
The experts at Tirron and Uson can help you choose the best tester for your job.