FAQ

Pressure decay leak testing is one of the most widely used techniques for detecting leaks in objects. The test process consists of 4 consecutive steps:

1. Preparation:
   The test part is first pressurized or vacuumed at a determined pressure/vacuum level.
2. Stabilization:
   After isolation, the system is left idle for a period to stabilize the air inside it.
3. Test:
   The system is monitored for any pressure variation using pressure transducers and/or differential pressure sensors. A pressure variation indicates the presence of a leak in the part, and the device shows if the test part is within an acceptable leak rate or not.
4. Venting:
   The test air is vented out to the atmosphere, and the part returns to initial pressure conditions and is prepared for the next test cycle.

This type of test is preferred due to its non-destructive testing (NDT) capability, quick testing cycle, high sensitivity, and accuracy in leak detection.

Air leak testing methods include several techniques depending on the application and required accuracy. Below are some common methods:

• • Dunk Testing:
    Dunk testing, also known as bubble testing, is one of the oldest and most basic air leak testing methods. The test is conducted by pressurizing the part or vessel, submerging it in water, and observing for bubbles that indicate escaping air or gas. The rate of bubble formation and size of the bubbles are directly proportional to the size of the leak. This is a simple, cost-effective method for leak location but cannot measure accurately or quantify the leak rate.
  • Tracer Gas Method:
    For devices with very low leak rates in the range of 10⁻⁵ SCC/sec or lower, the tracer gas or sniffer test can be used. These tests involve pressurizing the test part with a non-atmospheric gas, such as helium, hydrogen, or halogen, and using a sniffer probe to detect the leak location. These tests can be performed using two methods: with a sniffer probe to localize the leak or in a chamber to identify minute leak rates. Highly sensitive, these tests can identify and localize even the tiniest leaks but require manual operation and a controlled test environment to minimize external interferences like wind, temperature, and pressure changes.
  • Pressure Decay Leak Testing:
    The test part is first pressurized to a predetermined level, isolated from any pressure loss, and then monitored for any pressure drop. These tests can be performed either directly with reference to a master test object or indirectly using a chamber. These methods, which use pressure transducers and/or differential sensors, are fast and highly accurate for detecting and quantifying the leak rate.
  • Vacuum Decay Leak Testing:
    Vacuum decay leak testing operates on the same principle as pressure decay testing, but in this case, the test part or assembly is evacuated of air and monitored for any pressure increase in the system due to airflow from the external environment.
  • Mass Flow Testing:
    With the help of a flow meter, pressurized air is sent through the test part at a predetermined level and used to measure the flow rate. Typical applications include medical tubes, catheters, and HVAC leak detection.

Air leak testing plays a significant role in manufacturing processes across various industries. Below listed are a few of its key advantages:

• Quality improvement: Leak testing not only enhances the quality, reliability, and safety of products but also minimizes customer complaints by identifying and allowing corrections to be made early in the production process.
• Reduce failure rate: Early leak detection can prevent product failures and potential safety hazards that can be caused in the future. It helps to identify flaws in the manufacturing process, improve, and ultimately achieve higher-quality products.
• Cost reduction: Leak testers can significantly reduce operational costs. They help prevent product defects that can arise at the customer’s end. Additionally, the automated, nondestructive nature of these tests cuts down cycle times and operates at minimal costs, further optimizing production efficiency.
• Highly accurate and calibrated device: These devices can perform highly accurate tests with utmost precision. The low maintenance requirements of leak testers ensure smooth and continuous operation, requiring only annual calibration. This enables continuous performance with minimal downtime.
• Non-Destructive Test Nature: These leak testing devices facilitate safe, reliable non-destructive testing that preserves the integrity of the test part.

Leak rate calculations depend on several factors such as volume, pressure, and test cycle time. It is derived from the Ideal gas law. 

On a general note, the leak rate is given by

LR (atm·cm³/min) = 0.0006 × Vol (cm³) ×
(∆P/∆t) (Pa/s)

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Choosing the right air leak tester depends on several factors based upon your application. The most influential factors are:

• Acceptable leak rate: The “acceptable leak rate” is a critical parameter for selecting an appropriate air leak tester. It refers to the maximum rate at which a part can leak air and still meet operational standards. Determining this rate is essential as it influences the choice of both the leak testing method and the technology.
• Test pressure and method: The pressure level used during the test, along with the selected leak testing method, are crucial factors in choosing the appropriate leak tester. These elements are determined based on the specific application and requirements of the part being tested.
• Test piece characteristics: The shape and volume of your test part also play an important role in choosing the right leak tester. For instance, an EV lithium-ion battery pack is of large volume and requires specially designed leak testers that can conduct these tests within the shortest time period.
• Test environment: The environment in which leak testing is conducted affects your test results. Our F610 equipped with a water-proof case is an excellent solution to withstand external influential factors.
• Space: The availability of space in your testing facility or production line is another influential factor in choosing the right leak tester

Many regulatory requirements govern air leak testing procedures. A few of the standards are below

ASTM E2930 – 13(2021): Standard Practice for Pressure Decay Leak Test Method

ISO 20486:2017 – Non-destructive Leak testing – Calibration of reference leaks for gases

ISO 27895:2009 – Standard Practice for leak testing of valves in a vacuum system

ISO 20485:2017 – Non-destructive Leak testing — Tracer gas method

ASTM F2338-09 – Standard Test Method for Non-destructive Detection of Leaks in Packages by Vacuum Decay Method

ATEQ products adhere to international leak testing standards. Refer to our certificates and accreditations or contact us to know more.

Absolutely! Air leak testing can be semi-automated or fully automated and integrated into your existing production line for improved efficiency and accuracy.

It reduces your factory operational costs, provides real-time feedback on parts tested, and permits multiple product testing with the multi-channel option.

Check out our F620 or F6900 which permit single or multi-channel automated leak testing and can be easily integrated with your PLCs for automation, data collection, and analysis. Talk to our experts to know more about how leak testing can be automated in your organization.

Air leak testing is conducted by applying pressure or vacuum to a test part, vessel, or system and monitoring it for any presence of leaks in the system. The test object undergoes the following testing procedure:

• Fill / Vacuum time: The test part is sealed and connected to the test equipment. Depending on the test method, the test part is filled with air or gas or vacuumed according to production specifications.
• Stabilization Period: After reaching the set pressure or vacuum level, the system enters a stabilization phase to ensure that there are no temperature or pressure fluctuations within the system that can influence the results.
• Test Period: During this testing period, the test piece is monitored for any pressure changes in the system. Various types of leak testing principles can be followed here depending on the test accuracy. Test results are displayed on the equipment indicating if the product has a leak within acceptable levels or not. Also, the results can be transferred to your PC (monitoring system) via communication protocols.
• Venting: The test air is vented out to the atmosphere and the circuit is open. The test part returns to initial pressure conditions and prepares for the next test.

It is essential to acknowledge that every object in this world has some degree of leakage, but the key factor is whether it remains within acceptable limits. 

Leak testing is crucial because

• Safety: Ensures that it detects and prevents hazardous gas leaks or entry of contaminants into your test piece or system.
• Quality Control: To ensure that your test part is meeting the quality standards and regulatory requirements.
• Environmental Protection: To ensure that your test piece is leakproof and does not pollute or contaminate the surrounding environment.
• Improved product lifespan: To improve your product lifespan by restricting entry of contaminants or restricting wear and tear and damage due to continuous leaks.

Leak testing is a test method that is used to confirm the test piece’s tightness or to detect the location of a leak.

A leak can be defined as an unintended crack, hole, or porosity in an enclosing wall or joint that is meant to contain or exclude various fluids and gases. This defect allows the escape of the enclosed medium. Leakage occurs when there is unintended flow of fluid through the walls of a vessel or sealed container. This occurs due to the pressure difference between the inside of the vessel and the external atmosphere, causing air to flow from areas of higher pressure to areas of lower pressure.

Leak testing is conducted by applying a set pressure or vacuum to your test part and using various test methods such as pressure decay, bubble testing, or tracer gas sniffing, to detect, measure, and localize any leaks. The objective of air leak testing is to ensure manufacturers that their products are manufactured with the required leak-tight specifications to ensure safe and reliable operation.