The Beginner’s Guide to Leak Testing – Part 5: How to Select the Best Instrument for Your Needs

With the multitude of leak and flow instruments on the market, selecting the right or best leak instrument for your application can be a complex decision, but it doesn't have to be overwhelming.

In Part 5 of this series, we will guide you through the critical steps of choosing the best instrument for your specific needs. Whether you're performing simple leak tests, complex multi-step processes, or flow and burst tests, understanding the nuances of your application is key.

We’ll cover everything from technical qualifications like test volume, sensitivity, and throughput, to evaluating instrument manufacturers for quality, flexibility, and support. By the end, you’ll be equipped with the knowledge to confidently select the best leak and flow instrument to ensure efficiency, accuracy, and long-term value for your manufacturing process.

Technical Qualification: Defining Your Leak Testing Requirements

What’s the Application?

Before selecting a leak instrument, you must clearly define the application. This will be the foundation of your instrument choice. When speaking with our applications engineering team or sales specialists, this is the first topic we’ll discuss.

Your application could be:

• A simple leak test
• A complex test requiring multiple steps and program linkages
• A flow test, crack test, burst test, sealed component test, or flexible packaging test

During this conversation, we’ll help you identify key factors such as:

• Part or Product Volume: What is the volume of the product or how much volume can the product hold?
• Part or Product Material: What raw materials are used to manufacture the product? For example, polystyrene, PTFE, etc.
• Reject Leak Rate: What is the acceptable threshold for leakage?
• Test Pressure: What pressure or pressure range will the test be performed at?
• Time Available for the Test: What is the ideal or preferred cycle time for each test?
• Part of Product Description: Detailed information of the product being tested to understand use cases
• Part or Product Numbers: Identification of all parts to be tested

Additional details that may come up include:

• Working Pressure of the Product: What pressures does your product experience in operation or during usage?
• Liquid or Gas used in the Product: What medium is used when the product is in used in real-world situations?
• Product Usage in the Marketplace: How is your product utilized?
• Seal Requirements: Is the product intended to prevent liquid or gas leakage?
• Consequences of Leakage: What are the risks of failure, including product malfunction, deterioration, fire hazards, harm to surroundings, and costs to the end user?

These factors will guide the technical requirements for your leak testing instrument.

What’s the Leak Specification?

Once the application is defined, the next step is determining the leak specification. This will drive the selection of the most suitable testing technique and instrument.

The leak specification sets the criteria for pass/fail decisions and may be expressed in terms of:

• Volumetric Leak Rate
• Pressure Drop
• Flow Rate
• Force Reading

Armed with the leak specification and application, we can narrow down the options to ensure we provide the most accurate and repeatable results for your process. Additionally, this information helps us calculate the test cycle time to ensure that the instrument can meet production requirements.

What’s the Throughput and Environment for Testing?

Environment and throughput are key factors that determine the type of testing and instrument you’ll need to perform your part or product analysis efficiently. The testing environment is broadly categorized into:

• Lab Testing: This type of testing is performed in a laboratory or clean room to analyze the product, which is normally located in a different area or adjacent to the manufacturing floor. This type of environment can be a research and development lab for designing new products or a quality control lab to ensure the product batch is meeting product specifications and Certificate of Analysis (COA) generation.
• On-line Testing: This testing is performed directly on the production line, often requiring 100% testing of products produced during the manufacturing process. In this type of environment, the calculated cycle time can be longer than the production rate requiring multiple instruments or a multi-channel instrument, like the Optima vT.

On-line testing will also clarify the level of automation required, including:

• Input/Output Controls
• Program Linkages
• Communication Protocols
• Data Handling Capabilities

By the end of the technical qualification, we’ll have determined the appropriate technique, instrument type, and necessary features to meet your product testing requirements.

Are Resolution and Sensitivity Important?

Resolution and sensitivity are critical considerations in leak testing, but they must be evaluated holistically with long-term repeatability and stability as key factors.

Resolution
When instrument manufacturers claim ultra-high resolution (e.g., 0.0001 psi), it’s important to understand these figures may be based on ideal conditions without noise interference and real-world environments. To get a true picture of usable resolution, we consider the entire system: electronics, sensors, pneumatic components, and real-world conditions.

Sensitivity
Similarly, claims of extremely high sensitivity (e.g., 0.01 cc/min leak rate) should be viewed with caution as this may only be for specific applications. Actual performance depends on the part being tested, the environment, and the test specification. Focusing on exaggerated numbers without considering the total system could lead to costly mistakes.

System Flexibility
One of the most important factors in selecting a leak instrument is flexibility. As product designs evolve and testing needs change, a flexible system can adapt to new requirements, such as:

• Data Collection
• Statistical Analysis
• Bar Code Reading
• Temperature Compensation

While flexibility may increase the initial cost, it pays off in the long run by reducing downtime and avoiding additional costs over the system’s lifetime. A well-designed, flexible leak instrument ensures that you can meet future needs without investing in entirely new systems to meet new testing requirements.

Since this guide is tailored to first-time users or those new to the field, availability of support services is another crucial consideration. Ensure that your chosen supplier provides comprehensive support, maintenance, and training without hidden costs.

Instrument Manufacturer Qualification: Choosing the Right Partner

Selecting the right instrument manufacturer is as important as choosing the right instrument. The quality of your leak testing solution depends not only on the product but also on the expertise and support behind it.

Here are key factors to consider:

Range of Capabilities

A supplier with a diverse range of leak detection techniques or methods can objectively recommend the best solution for your application. Look for a manufacturer that can offer:

• Mass Flow
• Pressure Decay
• Vacuum Decay
• Pressure Increase
• Differential Pressure Flow
• Differential Pressure Decay
• Downstream Sensor Testing Capabilities
• Closed Chamber Analysis

Manufacturers with limited techniques may try to fit your application to their product, rather than recommending the optimal solution.

Quality Certifications

When evaluating manufacturers, ensure to look for manufacturers with certifications that demonstrate quality and reliability, such as:

• ISO 9001
• ISO 17025
• CE Mark (for European compliance)

These certifications ensure proper documentation, software validation, and overall system quality.

Support and Service

Finally, ask upfront who will provide support services. Will it be the manufacturer, a distributor, or a third-party representative? A reliable post-sales service ensures that your system continues to perform at its best throughout its lifecycle.

By following these guidelines, you can make an informed decision and select a leak testing solution that not only meets your current needs but is also adaptable to future challenges.

What's next?

This concludes our comprehensive series on The Beginners Guide to Leak Testing. Throughout this series, we have explored the fundamental aspects of leak testing, providing you with essential knowledge and practical insights to help you navigate the complexities of selecting and utilizing leak testing instruments. From understanding the importance of leak testing and exploring various methods such as air pressure and flow measurement, to examining advanced features of leak testers and offering detailed guidance on purchasing the right equipment, we have covered a wide array of topics to equip you with the tools needed for effective leak detection.

• Part 1 - Why Leak Test?
• Part 2 - Leak Testing Using Air
• Part 3 - Beyond Air Pressure & Flow Measurement
• Part 4b - Leak Tester Features
• Part 5 - How To Buy a Leak Tester

Leak Testing Resources on Demand

Want more leak testing basics?  You can find a plethora of resources right here at Uson.com.  Check out our Blog and Resources section for educational articles, test method library, videos and more.

Find the Right Process and Leak Tester for Your Application

If you're ready to find the right process and leak tester for your application, reach out to Uson for expert help.  Uson has helped thousands of product manufacturers around the world with their toughest application challenges for 60 years. We can help you too. Contact us today!