FAQ – Frequently Asked Questions


What is ATEQ?

ATEQ is the world’s leading manufacturer of automated equipment for leak testing, flow measurement, pneumatic and electrical testing, used in assembly lines, laboratories and workshops. ATEQ instruments operate in virtually every industry: automotive, aviation, medical, household appliances, electronics, packaging, water and gas fittings, construction and others.
ATEQ has offices in more than 40 countries, creating a vast network of local structures covering the entire world. Beside instrument sales and consulting they also provide comprehensive service, including joint work on the correct equipment implementation through on-site technical support, tests, trainings, after-sales service and calibrations. Thanks to this, selling the instrument is just one stage of a long-term partnership with our Customers.


What is a “leak-proof product”?

We encourage you to read the article in the press section explaining the meaning of a leak-proof product.

The article is available as part of the ATEQ Leak Testing Academy, committed to providing educational content on industrial leak testing, flow measurement, blockage testing and pneumatic testing used in production lines, laboratories and workshops through training, publications, articles, videos and application studies.


What is leak testing by air-air method?

The air-air leak testing method involves applying air to the tested element at a certain pressure (overpressure or vacuum) in an air environment at atmospheric pressure. The pressure difference between the interior of the tested element and the exterior environment generates an air leak.
There are many types of air leakage testing methods, such as:

Air methods are usually the most suitable and commonly used methods for leak testing of most industrial products.

Advantages:

  • easy automation
  • elimination of operator errors
  • speed
  • clear reject level
  • very low cost of air compared to gas methods
  • relatively low cost of equipment
  • wide range of applications
  • variety of air methods enables selection of the appropriate method to the test requirements
Disadvantages:

  • no possibility of locating the leak (however, it can be combined with other methods, such as locating the leak using foam, soap solution or the “bubble” method by immersing in water)

What is leak testing by air-water method?

The air-water leak testing method involves applying air to the tested element at a certain pressure and immersing the part in a tank of water. Leaks will become visible due to air bubbles escaping from the element. For that reason this method is also called the “bubble method” or “bubble test”.

Advantages:

  • relatively low cost
  • leak location
Disadvantages:

  • test automation impossible
  • operator errors
  • wet parts
  • no clear reject level
  • subjective assessment of leak size
  • difficult handling of tested part

What is leak testing by gas method?

The gas leak testing method involves applying gas other than air to the tested element at a certain pressure and detecting the presence of that gas in the surrounding environment.
Various gases or gas mixtures are used for gas leak testing, e.g. helium, hydrogen, carbon dioxide, sulfur hexafluoride (SF6), propane, butane, and others. Since many gases may pose a threat to the operator (e.g. flammable, explosive gases) or the environment (refrigerants, freon), technical gases are most often used, which are safe and cheap, like 5% hydrogen solution in nitrogen (5% H2 / 95% N2). The equipment used for such tests must be suitable for detecting the presence or concentration of the particular type of gas.
The most common types of gas leak testing methods:

Gas methods are usually used for very demanding tests that cannot be solved by simpler and cheaper air methods (very small leaks, very large volumes, high temperature of the tested item, localization of the leak). For the most restrictive requirements, helium leak detectors are used, equipped with a mass spectrometer.

Advantages:

  • leak location
  • high measurement sensitivity
  • ability to test large volumes
  • low sensitivity to temperature
Disadvantages:

  • high cost of equipment
  • high operating cost depending on the type of gas used and its consumption (gas consumption depends on the volume of tested parts and test pressure)
  • need for a skilled operator
  • complicated and time-consuming operation
  • need for good ventilation
  • large leaks contaminate the environment by creating a “gas background” and prevent resuming the tests

What is leak testing by pressure drop measurement method?

The pressure drop measurement (pressure decay) leak testing method involves applying air to the tested element at a certain pressure. After stabilizing the pressure in the tested system, changes in this pressure are measured. Air leaking from the test part generates a pressure drop. If the measured pressure drop is greater than the allowed tolerance level, the part will be rejected.
The most frequently used variations of the pressure drop measurement method are:

Advantages:

  • easy automation
  • elimination of operator errors
  • speed
  • clear reject level
  • very low cost of air compared to gas methods
  • relatively low cost of equipment
  • wide range of applications
  • variety of air methods enables selection of the appropriate method to the test requirements
Disadvantages:

  • no possibility of locating the leak (however, it can be combined with other methods, such as locating the leak using foam, soap solution or the “bubble” method by immersing in water)

Is it possible to use vacuum for leak testing by pressure drop measurement method?

Overpressure is most often used for pressure drop measurement tests, as compressed air from the supply network is cheap and available in nearly every plant. Under the influence of pressure, leaking air generates a certain pressure drop in the tested element proportional to the size of the leak.
Since tests are carried out in an air environment at atmospheric pressure, vacuum (underpressure, negative pressure) can also be used, under the influence of which the leaking air generates a certain increase in pressure (drop of negative pressure level) in the tested element proportional to the size of the leak. For tests in vacuum, a vacuum source is needed (e.g. a vacuum pump or generator).
When vacuum is used, the direction of the leak also changes, since air flows from the exterior environment into the interior of the tested element.

Advantages:

  • higher resistance to temperature fluctuations than in pressure tests
  • easy automation
  • elimination of operator errors
  • speed
  • clear reject level
  • very low cost of air compared to gas methods
  • relatively low cost of equipment
  • wide range of applications
  • variety of air methods enables selection of the appropriate method to the test requirements
Disadvantages:

  • no possibility of locating the leak (even when using e.g. foam, since bubbles would form on the invisible, inner side of the tested element)
  • necessary vacuum source (e.g. vacuum pump)
  • reachable level of vacuum is limited by atmospheric pressure

What is leak testing by absolute pressure drop measurement method?

The absolute pressure drop measurement (pressure decay) leak testing method is a basic, simple variation of the pressure drop measurement method.
It involves applying air to the tested element at a certain pressure, and after stabilizing the pressure in the tested system, changes in this pressure are measured. Air leaking from the test part generates a pressure drop. If the measured pressure drop is greater than the allowed tolerance level, the part will be rejected.
With the absolute pressure drop measurement method, the pressure change is measured by the same pressure gauge or transducer that measures the test pressure, so the measurement range of this pressure gauge or transducer must be greater than the maximum test pressure. To measure the pressure drop, the total (absolute, hence the name of the method) range of available pressure can be used. A large measurement range of the pressure gauge or transducer translates into poor resolution and low measurement accuracy, hence the absolute pressure drop measurement method is used to detect leaks that generate relatively large pressure drops, such as leak testing of very small components or detecting large leaks.

Advantages:

  • very low cost of equipment
  • easy automation
  • elimination of operator errors
  • clear reject level
  • very low cost of air compared to gas methods
  • wide range of applications
Disadvantages:

  • no possibility of locating the leak (however, it can be combined with other methods, such as locating the leak using foam, soap solution or the “bubble” method by immersing in water)

What is leak testing by differential pressure drop measurement method?

The differential pressure drop measurement (pressure decay) leak testing method is a very precise variation of the pressure drop measurement method.
It involves applying air to the tested element and a very tight reference element at a certain pressure, and after stabilizing the pressure in the tested system, changes in this pressure are measured. Air leaking from the test part generates a pressure drop relative to the pressure in the tight reference element. If the measured pressure drop is greater than the allowed tolerance level, the part will be rejected.
With the differential pressure drop measurement method, the pressure change is measured by an independent, precise differential pressure gauge or transducer, which measures the pressure difference (hence the name of the method) between the tested element and a very tight master (reference) element. The measurement range of this differential pressure gauge or transducer is very small, thanks to which it has a high resolution and measurement accuracy, which is independent of the applied test pressure.
The differential pressure drop measurement method is used to detect leaks that generate very small pressure drops, such as leak testing of large components or detecting small leaks.

Advantages:

  • high precision independent of test pressure
  • easy automation
  • elimination of operator errors
  • speed
  • clear reject level
  • very low cost of air compared to gas methods
  • relatively low cost of equipment
  • wide range of applications
  • variety of air methods enables selection of the appropriate method to the test requirements
Disadvantages:

  • no possibility of locating the leak (however, it can be combined with other methods, such as locating the leak using foam, soap solution or the “bubble” method by immersing in water)

What is leak testing by gas sniffing method?

The gas sniffing leak testing method (“sniffer”) involves applying gas other than air to the tested element at a certain pressure and detecting the presence of that gas in the surrounding environment by using a test probe with a sensor appropriate for the particular type of gas. The probe with a gas sensor is slowly moved along the tested product, “sniffing” the joints, seals, seams, welds and other elements where a leak may occur.
Various gases or gas mixtures are used for gas leak testing, e.g. helium, hydrogen, carbon dioxide, sulfur hexafluoride (SF6), propane, butane, and others. Since many gases may pose a threat to the operator (e.g. flammable, explosive gases) or the environment (refrigerants, freon), technical gases are most often used, which are safe and cheap, like 5% hydrogen solution in nitrogen (5% H2 / 95% N2).
Gas methods are usually used for very demanding tests that cannot be solved by simpler and cheaper air methods (very small leaks, very large volumes, high temperature of the tested item, localization of the leak). For the most restrictive requirements, helium leak detectors are used, equipped with a mass spectrometer.

Advantages:

  • leak location
  • high measurement sensitivity
  • ability to test large volumes
  • low sensitivity to temperature
Disadvantages:

  • high cost of equipment
  • high operating cost depending on the type of gas used and its consumption (gas consumption depends on the volume of tested parts and test pressure)
  • need for a skilled operator
  • sensitive to operator errors, e.g. too high probe movement speed or distance from the tested element
  • time-consuming operation, hence application most often limited to testing sensitive elements (joints, seams, welds, etc.)
  • need for good ventilation
  • large leaks contaminate the environment by creating a “gas background” and prevent resuming the tests

What is leak testing by gas accumulation in test chamber method?

The gas accumulation in test chamber leak testing method involves applying gas other than air to the tested element at a certain pressure and placing the part in a test chamber.
Gas leaking from the tested element gradually accumulates inside the test chamber, reaching an increasingly higher concentration. After a certain accumulation time, the leak detector collects a sample from the test chamber and measures the gas concentration in that sample.
Since the tested element is enclosed in a chamber in which the total leakage from the entire element accumulates, this method cannot be used to locate the leak.
Various gases or gas mixtures are used for gas leak testing, e.g. helium, hydrogen, carbon dioxide, sulfur hexafluoride (SF6), propane, butane, and others. Since many gases may pose a threat to the operator (e.g. flammable, explosive gases) or the environment (refrigerants, freon), technical gases are most often used, which are safe and cheap, like 5% hydrogen solution in nitrogen (5% H2 / 95% N2).
Gas methods are usually used for very demanding tests that cannot be solved by simpler and cheaper air methods (very small leaks, very large volumes, high temperature of the tested item, localization of the leak). For the most restrictive requirements, helium leak detectors are used, equipped with a mass spectrometer.

Advantages:

  • high measurement sensitivity
  • ability to test large volumes
  • low sensitivity to temperature
Disadvantages:

  • very high cost of equipment and tooling
  • high operating cost depending on the type of gas used and its consumption (gas consumption depends on the volume of tested parts and test pressure)
  • need for a skilled operator
  • no possibility of locating the leak
  • complicated and time-consuming operation
  • need for good ventilation
  • large leaks contaminate the environment by creating a “gas background” and prevent resuming the tests

Should the reference part be same as the test part when leak testing by differential pressure drop measurement method?

Of course YES!
Contrary to popular belief, using a reference element allows for significant time savings. Tested elements change temperature and volume under the influence of pressure. Maintaining symmetry between the tested and reference systems means that the thermal and volume stabilization of both systems is identical, thanks to which these fluctuations compensate each other and become invisible to the differential transducer. Since the transducer “does not see” these disturbances, the pressure drop measurement can be started much earlier and cycle time can be saved.

 

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Send your questions to info@ateq.pl or use the contact form.
Direct phone numbers may be found on our Contact page.

ATEQ also offers trainings in leak detection, flow measurement and correct operation of test instruments, as well as technical support tailored to the individual needs of our Customers.

Also feel free to check the materials available on-line at the ATEQ Leak Testing Academy.

Our engineers are at your disposal!