What is a leak-proof product?

INTRODUCTION

In everyday practice and in many areas of life, we deal with objects, products, devices whose important feature is tightness, ensuring their proper use in various conditions. Such products found in our daily practice are, for example, parts used in cars (tires, tanks, EV batteries, brake, cooling and air conditioning systems, etc.), household appliances (refrigerators, gas stoves, washing machines, dishwashers, coffee machines, etc.), packaging, medical devices (syringes, vials, blisters, …), water and gas fittings (valves, water filters, dispensers,…), electronic devices (watches, phones, module-sealed housings batteries…), and many more.

Manufacturers of these devices should ensure the quality of their products, min. through appropriate quality control in the production line. One of the parameters indicating the proper quality of the product is its tightness, so it is also necessary to control this feature of the product at the production stage.

In common understanding, the tightness feature of the product is defined in a “binary” way, i.e. the product can be tight or leaky. Such a feature defines the product only in a qualitative way, because we could similarly say that the product is “heavy” or “light”, or “long” or “short”. It can be seen that the product feature formulated in this way is imprecise, because criteria and tolerances are needed to quantify this parameter, which is tightness.

A good example of colloquially understood leak control is testing a leak from a car tire, when the wheel is immersed in water, and observing air bubbles escaping from the tire in the case of a leak. Then we can conclude that if an air bubble appears, the tire is leaking. We then make a “qualitative” distinction: the product is leak-proof or not leak-proof. At this point, the question can be asked:

• What will happen if the bubble appears only after a minute of observation?
  Either 10 minutes or after an hour… etc..
• How long should we observe the tire underwater to make a proper “tight/leaky” assessment?
  It can be seen that this type of leak control is not very precise, because we have not provided a “quantitative” criterion for the assessment of this feature of the product.

WHY LEAK TESTING IS SO IMPORTANT?

In the production process, if the quality control process should be more or less automated, we must measure a certain value defining the tested feature of the product, and then compare the result of this measurement with the adopted criterion determining the correctness of the parameter describing this feature. Such criteria are referred to as technical specifications for the product, which should be specified at the stage of developing the product structure in such a way that the product is adapted to its intended use and ensures its proper use by the future user. Such criteria may concern, for example, dimensions with a given tolerance, weight, electrical, thermal parameters, etc., always with tolerances acceptable for a given parameter.

1. HOW TO DETERMINATE A LEAK RATE?

The above remarks apply equally to the need to determine the tightness of the product in a quantitative manner, and to provide a criterion allowing for the qualification of the product as good (OK, tight) or bad (NOK, leaky).

Therefore, we need to define a certain parameter that will indicate the “degree of tightness” of a given product, and provide a range of values of this parameter, at which we will be able to qualify the product as “good” (OK) or “bad” (NOK).

Such a parameter, which we will define, will be a value that we will call “leak rate”, hence we will mark with the letter L. We can now formulate a criterion for this feature of the product, which we will call:

• „Value of Acceptable leak rate” (L_max).

It is very common to find a statements that since the product should be tight, no leakage can be allowed. However, in nature there is no concept of absolute tightness, just as it is impossible to create an absolute vacuum, or a temperature of zero Kelvin… In the example with the tyre, our evaluation criterion also depended on the time in which we observe the tested tyre. If we do not notice a leak for e.g. a minute, it does not mean that a bubble will not appear after a longer time…

The tightness of the product, like any other feature, should be adapted to its intended use and ensure its proper operation in the assumed conditions. There will be a different criterion, for example, for a valve operating in a nuclear power plant, and another for the exhaust system in a car, different for a high-pressure tank for hydrogen, and different for a bathroom faucet….

Leakage can occur as a result of a defect in the wall of the product, it can be e.g. crack, porosity, lack of adhesion, sealing defect, material defect, etc. Leakage is defined as the amount of a substance (gas, liquid…) escaping per unit of time from the tested product, as a result of the existence of this defect.

For a liquid (e.g. water), the definition of a leak would be:

• L = dV / dt, where dV is the volume of the liquid and dt is the time.

Since liquids are incompressible, the dV value is a good indication of the amount of substance escaping from the product.

For a gas, in order to determine the amount of gas coming out, we should give the pressure at which this volume is measured. This results from the equation of the state of an ideal gas (Clapeyron equation) which relates the parameters describing the state of the gas: pressure (P), volume (V) and temperature (T).

• P * V = n * R * T (n is the number of moles of gas, R is the gas constant)

Thus, the product of P * V is a measure of the amount of gas at a given temperature.
The definition of a leak for a gas (e.g. air) is:

• L_g = P * dV / dt

The above definition is determined in the units in which we define a leak (in the SI system):

• [ P * dV / dt ] = Pa * m³ / s, which is Pascal times a cubic meter per second.

As a reminder: Pascal (Pa) is a pressure equivalent to a pressure of 1 N/m² (one Newton per
square meter). This is a very small amount, corresponding to, for example, the pressure exerted by a 0.1 mm thick layer of water. Atmospheric pressure (1 bar) is 100 000 Pa, i.e. 1 Pascal is one hundred thousandth of atmospheric pressure

In practice, other corresponding units are used to describe a leak, the most commonly used include:

• mbar*l/s (millibar liter per second, a unit often used for helium tests).
• atm*cm³/s or atm*ml/s (atmosphere milliliter per second, a unit often used in the U.S.).
• bar*cm³/min, (bar cubic centimeter per minute), if leakage occurs into the atmosphere.

This last unit is quite commonly used in leak tests of products in production, because then we are dealing with the measurement of the volume of air escaping into the atmosphere from the tested product. Since the volume is measured at a pressure of 1 bar, this unit is often “simplified” and the leakage value is given in an abbreviated form:

• cm³/min or ml/min

However, it should be remembered that in any calculation it is necessary to take into account the fact that there is a “hidden” value of 1 bar in this quantity.

The leakage value given in this unit (cm³/min) also has a simple, intuitive interpretation with the immersion test in water. It is simply the total volume of air bubbles escaping from the product per minute, e.g. a leak of 5 cm³/min means that when the product is immersed in water, a total of 5 cm³ of air bubbles will escape in one minute.

The relationships between leak values expressed in different units are as follows:

• 1 Pa*m³/s = 10 mbar*l/s
• 1 (bar)*cm³/min = 1,67*10^-2 mbar*l/s = 1,67*10^-3 Pa*m³/s

A common industry leak unit is an “informal” unit

• 1 sccm

which is an abbreviation of the English words: „standard cubic centimeter per minute”. This means leakage into the atmosphere under standard conditions, i.e. at a temperature of 20°C and a pressure of 1013.25 hPa. This unit is basically the same as 1 cm³/min (for 1 bar), it only contains a specification about the ambient conditions.

Properly formulated requirements for the “class” of product tightness should therefore contain information about the permissible amount of medium (e.g. air) escaping from the product per unit of time, if it is filled with this medium at a specific pressure.

Thus, the specifications for product leak testing should contain two parameters:

• Test pressure P (when determining which medium we use for the test – most often air, helium, …).
• Maximum permissible leakage value (L_max).

An example of such a specification is the requirement for a car radiator at one of the manufacturers (air test):

• Test pressure: 2 bar
• Acceptable leak rate value: 1 cm³/min

One could ask why we allow such a leak for a product which is quite an important part of the engine cooling system in a car.

The radiator contains a water-based coolant during operation. The test, on the other hand, is performed using air, which penetrates through small holes much more easily than water. The difference in viscosity of the two fluids is important here: water has a viscosity about two orders of magnitude higher than air.

The difference in viscosity for the oil-air system is even greater, hence the acceptable air leak rate values for products containing oil (e.g. car engine lubrication system) are even greater, e.g. for the oil circuit in the engine head at one of the manufacturers:

• Test pressure: 500 mbar
• Acceptable leak rate value: 10 cm³/min

One of the most important “challenges” for the product designer (as well as for the manufacturer) is the correct determination of the quality requirements that the product must meet for such a features as tightness.

The question may be asked how the specifications for tightness are created, formulated by designers or manufacturers, to ensure the proper operation of the product.

There are several methods to determine such a parameter as the permissible leakage value.

1. The first is the analysis of physical phenomena related to the flow/leakage of a specific medium by a defect causing a leak. Such a theoretical analysis can be carried out on the basis of the laws of physics for the flow of substances through theoretical models of product defects. There is, for example, a simplified model of flow through a defect, in the form of a round hole in the wall of the product and a given diameter, at the given pressures on both sides of the hole. Assuming a laminar (viscous) flow, the Hagen-Poiseuille law can be used for the flow of gases and liquids through such an hole.

In addition, phenomena such as surface tension for the liquid (blocking the leakage in some cases), different defect geometry, etc. can be taken into account. Such an analysis allows, for example, to determine at what air leakage value (at a given pressure) the liquid will not escape from the product (the product will be tight to this liquid). Such analyses are used for many products in which there is a liquid during operation and the test is performed with gas (air, helium, …). Phenomena related to flow (leakage) due to real defects of various kinds are described by complicated laws, however, the use of simplified models allows for a relatively good determination of the L_max value (e.g. for air, at a given test pressure). Such models also allow for the analysis of the dependence of the leakage on the diameter of the defect (or its geometry in general), on the test pressure, viscosity of the medium, etc. More detailed data on this topic can be found in the literature on the subject, training materials, and the Internet.

2. Another method to determine the specifications for the product leak test is to perform a leak tests using a selected production method (e.g. air), and then to carry out experimental tests in simulated conditions of real operation of the product. On the basis of the comparison of the results, it is possible to find correlations between the results of tests used in production (e.g. with the use of air) and the appearance of defects that can be encountered during the use of the product. In other words, we can determine what air leakage can be allowed in given conditions, so that it does not affect the proper use of the product. There are many studies available in the literature describing the results of experiments consisting in finding a correlation between air leakage and leakage for different liquids for the same defects. In particular, such research was carried out for the automotive industry, where many parts and subassemblies contain liquids such as fuel, brake fluid, coolant, oil.

These liquids work in different pressure and temperature conditions, so it is necessary to simulate such conditions in experiments, and determine what defect of the product we can still allow so that it does not affect the actual operation of such a component in the car. In the conditions of serial production for such a car part, tests are usually performed by air, hence the need to find correlations between the results of tests carried out using different methods. One example of such a method of determining the requirements for the leak test is also the testing of water fittings for common use (valves, taps, connectors, etc.).

The test consists in testing workpieces with defects detected by the air method and using water under simulated operating conditions (at different pressures and temperatures).

2. WHICH OTHERS CRITERIAS CAN DETERMINE A LEAK RATE?

Specifications for the leak test are often given directly in the standards for a given type of product, these are often the standards that apply to all manufacturers of a given industry, in a given country or in the world. An example is the standards for the tightness requirements of gas fittings for domestic use, where the following conditions are explicitly stated: permissible leakage of 1 cm³/min for a test with air at a pressure of 150 mbar. Similarly, in generally applicable standards, specifications for the tightness of air conditioning and refrigeration systems are given. For these products, the permissible leakage value results from the permissible loss of the refrigerant during the period of operation. A typical value found in the standards is a maximum loss of 1 gram/year. Some manufacturers have their own standards for a given type of products, defining their quality properties on the basis of previous research and production and exploitation experience.

Therefore, if a manufacturer of a similar product would like to formulate his own specifications, he can use the experience of other manufacturers, or standards, if they are generally available.

A very important factor influencing the determination of tolerance for each parameter determining the quality of the product are economic considerations. According to the principle of „fitness for purpose”, i.e. adaptation to the intended use, the product should meet certain quality assumptions to such an extent that it can be properly used, and at the same time its price is acceptable to the user.

In highly competitive conditions, manufacturers try to adjust quality parameters so that the production process is profitable and the product can be sold on the market. This involves some “optimization” of production processes, which can sometimes reduce quality. As we can see, it is a certain trick to find a compromise between economic factors (price, profitability of production) and quality parameters of the product, which depend on the production technology used, quality control, etc.

The requirement of an appropriate “class” of tightness for the product is also one of the parameters where such a compromise is needed. For example, manufacturers use different leak testing methods and different leakage limits for the same product. As an example, we can mention the elements of the fuel system in a car, where values from less than 1 cm³/min to several cm³/min can be found. In the case of high requirements for the tightness of the product, helium methods must be used for testing, which are much more expensive than air methods.

Hence, for example, the prices of cars in which such components with “stricter” criteria are installed, can differ even several times depending on the car brand.

In addition to the economic aspects for the formulation of specifications for the tightness of the product, it is necessary to mention very important other factors that must be taken into account, such as the safety of use of the product, its impact on the environment, etc. Only the combination of all aspects: technical, technological, economic, environmental and safety allows for the proper determination of the specification for this feature of the product, which is its tightness.

The formulation of requirements for the product leak test, in the form of specifying the acceptable leak rate for air at a given pressure, allows to assess, in a certain sense, the geometry of the largest permissible defect of the product (diameter, shape, form of the defect), for which the correct use of the product in accordance with its intended purpose is still ensured. This is mainly used for products in which there is a medium in the form of a liquid or gas during operation, and the leak test allows to check whether, under the assumed requirements, the medium will not escape outside the product during use. An example is parts and components in automotive production, where tightness must be ensured due to the possibility of leakage of various fluids. Such tightness is assumed to be ensured if the size of any defects in the product does not exceed certain sizes. Then, in production air tests, the permissible leakage is directly related to the maximum size of the defect.

There are also other formulations of specifications for production leak tests, depending on the type of product and its operating conditions.

If we are dealing with a product in which a constant pressure should be maintained for a certain period of time, tightness can be defined as the maximum permissible pressure drop during operation. An example is the car tire mentioned above, in which the tightness can be determined assuming that the pressure does not drop more than, for example, 0.5 bar during the year. Of course, when testing such a tyre in the production process, we do not have such a long time to detect this assumed maximum pressure drop. The question arises as to what method and at what parameters of such a test should be performed. If a leakage value is measured, the criteria in the form of a permissible leakage value should be linked to the pressure drop requirements. Then, by performing a quick leak measurement, we detect defects in the product that could cause its leakage. However, there is a problem with such a direct relation between this leakage value (which corresponds to a certain size of a single defect) and the pressure drop in the product, because it may happen that there are many micro-defects in the product (undetectable by leak testing equipment), which in total cause a greater pressure drop than assumed. Therefore, in such cases, methods for measuring pressure drop will be more reliable.

Another example of a different formulation of specifications for leak testing is the requirements for refrigeration and air conditioning systems, where the maximum amount of refrigerant gas that can escape in the long term is given. The most common leakage limit for such device is 1 g/year (one gram per year). If the tests are carried out in the production process, e.g. using the helium method, appropriate conversions of this limit value should be made into a leakage value for helium, generally given in units of mbar*l/s (millibar liter per second).

In the packaging, cosmetics and medical industries, there are sometimes the specifications for leak testing, in the form of the maximum diameter of the defect that must be detected (e.g. 0.05 mm). When using a production test method, either by means of pressure drop or leakage measurement, appropriate calculations should also be made using the laws describing the dependence of the leak (flow) on the geometry of the defect. It should be remembered that such theoretical relationships apply to simplified conditions (e.g. regular shape of the defect), so they can be the basis for an approximate determination of the acceptable leak rate value. In such a case, it is also possible to confirm the assumed values by performing measurements on products with standard defects, or with the participation of appropriate leakage calibrators and masters.

Another important area in which leak tests are used is the production of parts that should be airtight due to their use in changing environmental conditions. This applies to e.g. devices exposed to precipitation, immersion in water, dust contamination with moisture, etc. For such devices, the requirements of airtightness are defined by IP standards, which specify to which external factors the product should be resistant. An example is the IP67 standard, which requires the product to be sealed when immersed in water to a depth of 1 m, for 30 minutes. A similar requirement is the water resistance of the watch, when submerged, e.g. to a depth of 50 m. At this depth, there is a pressure of 5 bar, which immediately determines the requirements for the pressure at which the test should be performed.

Other IP standards specify the requirements for “splash-proof” and “dust-proof”, etc. Again, the problem arises how to select the conditions for production tests of such products so that they meet the requirements of IP standards. In mass production, where rapid air tests are used, it is impossible to reproduce the conditions formulated in these standards. Therefore, it is necessary to carry out appropriate calculations or perform comparative tests to find correlations between the requirements of the standards and the criteria for the leakage values measured in the production tests.

The problem of airtightness of devices according to IP standards or similar standards and conditions for testing tightness in production is emerging more and more often in various fields. An example is the entire electric car industry, where it is necessary to ensure adequate tightness for batteries, electronic components, wiring, etc. Other examples are the production of waterproof devices containing electronic components inside a sealed case, such as mobile phones, watches, sensors, telecommunication components, cameras, etc. Such devices should be tested in the mass production process, so it is necessary to formulate specifications for leak tests in such a way that they can be adapted to the requirements of the relevant standards and to ensure their proper operation.

To sum up, in order to ensure proper leak testing of products in the mass production process, it is necessary to formulate requirements and specifications specifying the testing method and parameter values to determine whether a product is “good” (leak-proof) or “bad” (leaky). Depending on the type of product and its intended use, it is often necessary to adjust the acceptance criteria for the measurement of the leakage rate (during production tests) to the quality performance assumptions for the product. This involves the need to carry out analyses using laws describing relevant physical phenomena, or the results of laboratory research and experiments, and taking into account economic, environmental and safety aspects. Therefore, it is necessary to have extensive knowledge in various fields and extensive experience to solve many issues related to product tightness testing in production conditions.

CONCLUSION

Thanks to their competence and many years of experience in the use of various leak control methods in many areas of production, ATEQ engineers have the knowledge to propose solutions related to the testing methodology, selection and optimization of test parameters, definition of criteria and specifications for quality control in production.

The transfer of knowledge can take place through consultations, participation in tests and experiments related to a specific applications, as well as through training organized in the Company’s office or at the Client’s premises.

ATEQ’s offer includes instruments and devices that can be used in practically all applications in production, from detectors operating on the principle of air pressure drop measuring, through direct testing of flows and micro-leaks using air, helium, hydrogen and electrical methods.

ATEQ engineers provide their knowledge and experience at every stage of the implementation of leak control in specific applications in the customer’s production plant.

WŁODZIMIERZ WOJDOWSKI
Through education and passion physicist. He obtained a Doctor of Physics degree and was a doctoral student at the University of Warsaw. For 10 years, he was a university lecturer at Warsaw University’s Faculty of Physics, then worked for six years at the Polish Academy of Science, dealing, among other things, with non-destructive research. The next career step was to work in the early 1990s for the French company ATEQ, with which he is still associated today. He was President of ATEQ Poland before handing over the subsidiary’s management to his son Wojciech Wojdowski in 2022.

Tightness under control

ATEQ anniversary

We talk about the decades-long history of ATEQ, contemporary standards in leakage control
and the importance of cooperation with integrator companies with Włodzimierz Wojdowski,
the founder of the Polish subsidiary of the international company ATEQ.

Last year ATEQ, having a subsidiary in Poland, celebrated 45 years of activity. What were the beginnings?
The company was founded in France, starting its operations with production, which – as was often the case at that time – was carried out in a garage. The first solution produced was a device for testing leakage. The market demand for this type of product was starting to grow rapidly at that time. Leak testing, which was the focus of ATEQ’s attention at the beginning of its activity, remains a key area of ​​the company’s activity to this day. This applies to testing tightness, leak detectors and flow testers in relation to air and pressure, excluding the flow of media, e.g. liquids. Initially, ATEQ devices were used, among others, to test the tightness of gas tanks on ships. Later it turned out that such tests are very much needed in production processes. One of the first areas of application was the production of household appliances, e.g. gas cookers, which were becoming increasingly popular in France. Leak tests were needed at all stages – from the production of components, through their assembly, to the final control of the complete device. After the household appliance sector, which was the first recipient of ATEQ solutions, it was time for applications related to the automotive industry and the production of car parts. Due to the variety of these components and the need to produce them in large quantities, the production of such parts is very automated, so there was a great demand for testing the leak parameter on the production line – automatically, quickly, reliably and ensuring measurement precision.

What is ATEQ’s development strategy today?
The dynamic development of the parent company, ATEQ France, meant that the company’s solutions began to reach other European markets. The policy adopted by Jacques Mouchet – the founder of ATEQ and currently its main shareholder – assumed from the very beginning that the company would not look for distributors, but would open subsidiaries. This strategy results, among other things, from the desire to provide each customer not only with access to our solutions, but also with support at all stages – from selecting the test methodology through performing tests and examinations for a specific application, to launching the equipment, consultations, training, etc. This philosophy – to offer the customer comprehensive support, not just a device, and to be as close to the recipient as possible directly, not through distributors – remains unchanged. Thanks to our know-how and experience, we can support customers in choosing the right solution and the right method of leak testing, as well as provide assistance in the field of service or calibration. I believe that this approach is behind the company’s success. There are already about 30 ATEQ subsidiaries operating worldwide, employing a total of about 500 employees, and the Asian region is currently in the spotlight. Subsidiaries are already operating in China, Japan, Korea, Singapore, among others, and there are plans to launch more.

And what were the Polish beginnings like?
ATEQ’s history in our country began in 1991. At that time, the company noticed the potential of the emerging markets of Central and Eastern Europe, and I became its representative for Poland, the Czech Republic and other countries in the region. An important and interesting experience for me was observing the development of industrial technologies, which was very dynamic in the 1990s. It was a moment of market transformation and no one had yet dreamed of such testing methods offered by ATEQ devices. ATEQ’s first customers in Poland, similarly to France before, were primarily manufacturers of household appliances. However, from the very beginning, the target direction of business development was industrial production, not just the consumer goods sector. In 2001, i.e. 10 years after I became ATEQ’s representative, a subsidiary of the company was established in Poland. Due to the level of market development, it was considered necessary to increase the scale of operations. This also applied to other Eastern European markets, which is why the decision was made shortly afterwards to open an office of the Polish subsidiary in the Czech Republic. This was our Polish initiative, which enabled us to operate on a larger scale, including the Czech and Slovak markets. Today, the Polish subsidiary also has a representative in Hungary and Romania.

Where is the location of devices production that are sold to countries around the world?
Production takes place in France. Part of the assembly is carried out in China and the USA, which facilitates global operations, but the “hearts” of the devices are manufactured in France.

The company is currently intensifying its operations in several sectors. Which industries are they?
After a long period of ATEQ’s industrial production activities began its expansion in the aviation sector, introducing pressure testers to its offer, which can be used very widely – from gliders to Boeings. They allow testing of on-board systems, e.g. measuring the altitude or speed of an aircraft. We also supply electrical testing devices and battery testers. These are the three main points of the offer for the aviation industry. When we entered this market, it was already heavily dominated by renowned manufacturers of this type of equipment. Despite this, ATEQ managed to gain a strong position, and our customers today include Airbus, Boeing, Embraer, and even the armies of some countries. In the aviation sector, ATEQ provides solutions both for aircraft service centers and for the production of aircraft and their components. The Polish branch sells aviation equipment throughout South-Eastern Europe. We record large sales, for example, in Serbia, where many investments are currently being made. The recipients of our solutions include the Serbian army. Another area that is currently the subject of our interest is TPMS. Tire Pressure Monitoring Systems are systems for monitoring the pressure in car wheels. Currently, each tire has a sensor that communicates by radio with the car’s on-board computer. This system must be checked periodically, and we offer devices that allow such checks to be carried out. They can be found, for example, at tire repair stations, service stations and dealerships. In Poland, there is a central ATEQ service for the TPMS area in Europe.

The automotive industry, which holds a significant position among the recipients of ATEQ solutions, is undergoing a clear crisis during the pandemic. Is it noticeable for the company?
This is an interesting question, because our situation in this regard is very interesting. After a slight slowdown, which we managed to survive in quite good condition, there was a significant rebound. Previously suspended projects were resumed, budgets were unfrozen and this year we are recording an exceptionally large increase in sales in this segment. At the moment, we are seeing a certain flattening of the earlier recovery on the market, which is probably the result of problems with production downtime, but our results are very good.

A relatively new issue is leak tests in the production of electric vehicles. Can ATEQ’s knowledge and experience in testing combustion or turbojet engines be helpful?
Electromobility is another point on the map of the most important business sectors, after the aforementioned aviation and TPMS systems, that we currently focus on. Until now, the largest recipient of ATEQ solutions was the manufacturing sector of parts for combustion cars. The production of such cars will slowly be phased out and we must follow these changes. Thanks to our technology, experience and know-how, we have a fairly comfortable situation, but so far we have not had solutions strictly for the electromobility sector, which is why a separate department was created to develop activities in this area.

IN THE CASE OF ELECTRIC CARS, THE NEEDS FOR LEAK TESTS ARE COMPLETELY DIFFERENT THAN FOR COMBUSTION CARS. VERY HIGH REQUIREMENTS APPLY ESPECIALLY TO THE BATTERY, WHICH CANNOT HAVE CONTACT WITH MOISTURE, WHICH REQUIRES A HIGH LEVEL OF TIGHTNESS. IN ADDITION, THERE ARE TECHNICAL CHALLENGES IN TERMS OF ACHIEVING PRECISION AND APPROPRIATE MEASUREMENT SENSITIVITY.

When did you start your adventure with electro-mobility?
About three years ago. In the case of electric cars, the needs for leak tests are completely different than for combustion cars. Very high requirements apply especially to the battery, which cannot have contact with moisture, which requires a high level of tightness. In addition, there are technical challenges in terms of achieving precision and appropriate measurement sensitivity. In order to test electrical systems, develop methods for checking leakage that can be used in the production of electric cars and meet other market needs, we have created the aforementioned separate division in the company focusing on electromobility. We develop some solutions together with partners – for example, in cooperation with Toyota, we implemented solutions for testing insulation in electric motors. We conduct many tests, not only for our own needs, in our laboratory. An example is cooperation with the Swedish company Northvolt, which wants to produce state-of-the-art batteries for electric cars. It is currently building a factory in Gdańsk, and the Polish branch of ATEQ is testing solutions and checking the possibilities of their application in production. The well-known ATEQ brand, combined with our know-how, makes our position in the area of ​​solutions that we offer to the electromobility sector strong compared to the competition.

Are there any industrial sectors in which ATEQ is not present with its solutions and plan to start cooperation with them?
One of such sectors is the medical industry. This is a specific industry, and leak tests are needed in the production of many elements, such as syringes or pumps. In this case, however, offering only devices is not enough – being present in this sector requires cooperation with a company that will install them in a machine adapted to work in medical production conditions. This is still ahead of us. However, we are already present in most industrial sectors where leakage control is required in production. Outside the sphere of our interests is heavy industry, e.g. shipbuilding, metallurgy, pipeline production, etc. In this area, the needs for tightness control are specific and we do not offer solutions for these industries. Sometimes, however, representatives of these sectors consult with us on the solution to the problem, because even though our devices are not suitable for them, we can provide them with knowledge and sometimes also technical support. Without false modesty, I can risk saying that we know leak testing like no one else in Poland.

In addition to product solutions, you also offer services. What kind?
We are seeing a very large increase in calibration services. We perform several thousand calibrations a year, not only in the scope of our devices, but also solutions of other, competitive manufacturers who do not offer such services. This is a very important area of ​​activity, because the quality of measuring devices and correct calibration must be confirmed by certificates, which must be renewed every year. We are developing our activity in this area and are currently in the process of applying for laboratory certificates, including accreditation according to the ISO 17025 standard, appropriate for pressure measurements. After obtaining the ISO certificate, we will join the group of several ATEQ laboratories that have this accreditation and we will be able to expand our calibration services.

ATEQ also supports customers through training activities. Can you tell us more about it?
When we launch a device at customer’s premises, we always organize operator training. Often, customers want to deepen their knowledge, and then we organize training for them – at our office or at the customer’s premises. A typical training lasts two days. On the first day, we present the theory – often broadly, not limiting ourselves to operating specific devices, but also familiarizing recipients with methods of leakage control, etc. – and on the second day, we translate it into practice, i.e. working with specific devices or applications. Thanks to the knowledge acquired during the training, in the event of problems, the company can often solve them on its own, without having to send equipment to us or call our employee. At the same time, we offer service – warranty and post-warranty – and technical support. A customer who delivers broken equipment to us can collect the repaired device within an hour. We guarantee high availability of parts and knowledge, which allows us to eliminate problems very quickly.

Who dominates the group of recipients of ATEQ solutions – the end customer or integrator companies?
I think that the balance of power is distributed more or less in half, perhaps with a slight advantage of integrator companies. In my opinion, one of the sources of ATEQ’s success in Poland is the fact that we have many integrator companies with very high competences. They are usually created by Polish engineers, enthusiasts with extensive knowledge, who build production lines and assembly stations. At the moment, we are cooperating with over a hundred such companies. It fills me with great joy, and the effects of this activity are best visible in the fact that large corporations carrying out production in Poland do not order production lines, assembly stations or their components from the West, but in our country. Not everyone is aware of this. It is quite a common belief that the activity of integrator companies in our country comes down mainly to the assembly of solutions on production lines. Meanwhile, Polish companies often create these lines or assembly stations from scratch.

How strong is the competition on the market in which you operate?
There is a visible difference between Poland and other markets. In Poland, ATEQ has by far the strongest position when it comes to companies providing solutions such as ours. The Polish market is dominated by distributors of various devices from many companies, who usually do not offer the same support and competence as we do. In the Czech Republic, the competition is stronger. ATEQ remains the leader in offering solutions for leak testing on the market of our southern neighbors, but other manufacturers, mainly from Germany, are starting to appear with a similar offer.

How can you sum up the many months of operating under pandemic conditions?
Initially, there were great concerns. We limited our presence in the company, we worked in two shifts. However, in terms of financial results, we felt practically no changes. Projects in the industries we work for are usually long-term, often lasting several months or even many years, which is why the pandemic did not take its toll on us financially. Now, when various initiatives and activities are gaining momentum again, we are recording turnover that we did not expect and I do not rule out that this will be a record year for us in terms of financial results. Recent years have also been years of prosperity for us, and the annual increase in turnover has reached even 15-20%. However, concerns still accompany us – on the one hand, the implementation of various projects has been resumed, and on the other, the pandemic continues and there are shortages in production. We will also increasingly deal with the elimination of combustion cars from the market, the production of which was associated with a significant part of our revenue. Therefore, we must constantly be vigilant and ready for changes, hence, among others, the decision to develop the offer for electromobility.

Interviewed by
Urszula Chojnacka
AUTOMATYKA

WŁODZIMIERZ WOJDOWSKI
Through education and passion physicist. He obtained a Doctor of Physics degree and was a doctoral student at the University of Warsaw. For 10 years, he was a university lecturer at Warsaw University’s Faculty of Physics, then worked for six years at the Polish Academy of Science, dealing, among other things, with non-destructive research. As part of the contract, he supervised the construction of gas pipelines in Syria. The next career step was to work in the early 1990s for the French company ATEQ, with which he is still associated today.
He is a keen sailor. He likes cycling, table tennis, traveling and books, especially popular science and physics books. Today, his favorite way of spending free time is also with his grandchildren.

ATEQ solutions for testing in electric vehicle production

ATEQ is an international supplier of advanced measuring devices for industrial quality control, with over 45 years of experience.
It specializes in leak testing, as well as flow and electrical parameters measurements for products in assembly lines.
One of the largest recipients of ATEQ devices is the automotive industry, where product leak testing methods are very widely used.

A standard combustion engine vehicle has hundreds of different parts that require leak testing at the production stage. These are such systems components as the engine and gearbox assemblies, fuel, brake, air conditioning, lubrication, cooling systems, etc. However, the design of electric vehicles is different, which means different requirements, also in terms of testing the quality of components.

In mass production of electric vehicles, the use of leak tests is a relatively new challenge, due to the specific quality requirements for components and parts used in these vehicles. One of the critical areas related to the proper functioning of electronic and electrical systems, such as batteries and cells, sensors, control elements, etc., is ensuring the tightness of systems and components. Any, even trace amount of water from the environment can pose a threat to the proper functioning and even the safety of the vehicle user. Such challenges arise not only in the production of electric cars, but also in relation to such electrically powered vehicles as trucks, motorcycles, trains, airplanes, drones, and even scooters, bicycles and other electric “gadgets”.

ATEQ, focused on finding innovative technical solutions, has developed new ways of testing these components in mass production. It also offers control and measurement equipment and devices for testing using various methods, adapted to the quality specifications of individual products.

Tightness under control

One of the most important quality parameters subject to 100% quality control is the tightness of components. ATEQ, as a company with many years of experience specializing in such tests, participates in the specification of quality criteria together with manufacturers and offers appropriate equipment for production tests. The most popular methods of leak testing products are pressure measurements, using air as a medium. The pressure drop, leakage or air flow are measured directly. Adapting these methods to the high tightness requirements for electrical and electronic devices, ATEQ has developed theoretical models of leakage correlation for various media. The aim of these studies was, among others, to determine the maximum air leaks for which waterproofness of components will be ensured, in accordance with the specifications, often defined as compliance with IP5X or IP6X protection classes. These models were then confirmed in many experiments and tests performed by qualified engineers in ATEQ subsidiaries in many countries around the world.

The waterproof parameter is of particular importance for electric battery packs, where even trace amounts of water are unacceptable. An additional difficulty in testing these components is their large volume, which limits the sensitivity of testing using air methods. ATEQ has developed equipment and patented solutions that significantly increase leak detection, while ensuring process stability under production conditions. ATEQ equipment and high-resolution differential pressure transducers are used, as well as a patented method of compensating the impact of ambient conditions on measurement (DNC technology). This allows for fast, stable and very precise leak tests to be performed in mass production. The devices communicate with the production line controllers, ensuring full automation of the quality control process.

ATEQ has extensive experience in testing waterproofness of components containing electronic driving assistance systems, such as various types of sensors, cameras, lasers, lidars, etc., increasingly installed in vehicles, not only electric ones. The specificity of such tests is usually the inability to fill the product with air, due to the closed housing. In this type of housing, membranes are often installed, ensuring watertightness and allowing for the equalization of internal pressure with atmospheric pressure. Testing such parts requires the use of special functions of closed components, often including measurement of proper membrane assembly, performed using flow meters. In some designs, check valves are used instead of membranes, which are also subject to functional tests. ATEQ equipment with the appropriate configuration for a given product is used for such tests.

Industrial components leak tests are aimed solely at detecting and rejecting leaky products. If full diagnostics of detected defects is needed, e.g. their location, methods using gas detection are used. ATEQ offers gas detectors (sniffers) that use forming gas for detection, containing a small (and safe for the environment) concentration of hydrogen in nitrogen.

Air ionization methods are also used for leak testing of plastic battery housings and car batteries, using devices developed at ATEQ. Electric motors in vehicles are located in sealed housings, isolating the engine components from the influence of external conditions – humidity, water splashes, dust and other similar contaminants. Complete assembled housings of enclosed motors are also subject to leak tests, and therefore require the use of appropriately precise equipment, similar to the previously described applications.

The basic element of each battery is a cell. The battery consists of a set of cells, isolated from each other by plastic covers. ATEQ has developed a method for testing these covers using ionized air. A leak test using this method can be used to assess the complete insulation of cells, as well as to locate possible defects. Similar methods and devices are also used in winding insulation tests in electric vehicle motors.

Additional measurements

In addition to leak testing devices – which is the company’s main focus – ATEQ has developed many other innovative solutions for testing components in production. In the case of electric vehicles, proper maintenance of battery cells is important. Based on ATEQ’s experience with aircraft battery testers, devices based on charging and discharging cycle measurements have been developed, allowing the condition assessment of the complete battery. So-called balancers, used when assembling or replacing faulty modules, are also intended for maintenance and servicing. These devices enable the performance of electrical balancing cycles of the entire battery, i.e. equalization of the charge of individual cells.

A large amount of heat is generated during battery operation, so it is necessary to use cooling systems, most often using appropriate heat exchangers containing a glycol-based cooling liquid. The penetration of this liquid into the battery components can be dangerous, so precise leak testing methods of such systems are also necessary, mostly based on pressure drop measurement or mass air flow measurement. Another important parameter subject to testing is the patency of the exchanger’s cooling channels, which is tested with appropriate ATEQ flow meters. Gas and appropriate leak detectors are used to locate any defects.

Traditional applications

It’s important to note, that in addition to new applications for components leak testing, many traditional applications for testing leaks in automotive components still exist in electric vehicles. Such leak tests include brake systems, headlights and lamps, ABS systems, central computer electronics, steering components and air conditioning systems. The methods and specifications used to check such products are similar to the differential pressure drop measurements used in production to date, as well as direct leak or flow measurement methods.

In electric vehicles, as in “regular” cars, tire pressure monitoring systems are used. TPMS systems (Tire Pressure Monitoring Systems) are based on special sensors mounted inside the wheels, which measure the pressure and use radio waves to send information about its possible drop to the on-board computer, e.g. in the event of a tire failure. ATEQ is a manufacturer of the most advanced diagnostic devices on the market for testing and servicing these systems, which also allow for programming and copying sensors, entering data into the car’s computer, etc. The recipients of these devices are car service and maintenance stations, tire producing companies, as well as car factories, where TPMS systems are checked on production lines using special, industrial versions of ATEQ diagnostic devices.

New answer to new challenges

Modern vehicle manufacturers are facing many new challenges during the production process, such as the increasing complexity of new vehicles, new technologies and the increasing pressure to achieve the highest level of quality in order to avoid threats to safety and operating conditions. To meet these new challenges, ATEQ offers devices for testing leaks, flow and other parameters of systems installed in electric vehicles, to ensure the quality of many components throughout the production process. ATEQ engineers have extensive experience in existing applications for testing the quality of components in automated production lines. They are also ready to design new solutions, within the framework of research in their own laboratories and with the participation of specialists from production plants, as well as in cooperation with integrator companies implementing complete solutions for automatic assembly and quality control. With offices and experienced engineers all over the world, ATEQ can provide local support in developing the optimal technical solution for industrial quality testing of products and components. At the same time, it offers full service support for purchased devices, periodic calibrations, training, etc. ATEQ engineers are at your disposal.

Looking forward to Your cooperation.

dr Włodzimierz Wojdowski

ATEQ

ATEQ READY TO TEST
HEV / EV / PEV / Fuel Cell EV VEHICLES

Jacques Mouchet
President, ATEQ

Whether it involves electric cars, trucks, buses or bikes, the ATEQ Group, a multinational measurement solutions provider with more than 45 years of experience, provides the quality processes car manufacturers require to manufacture better, faster and more reliable HEV / EV / PEV / Fuel Cell EV vehicles.

Using leak testing in the mass manufacturing of electric vehicles is relatively recent since the transportation industry was accustomed to testing internal combustion engines and turbojets. The drive away from fossil fuels and CO2 emissions has driven the development of new technologies. These new devices present new challenges for production line leak testing. Testing for leaks in one submarine electric motor or battery system per year versus leak testing thousands of vehicle motors per day has very different testing solutions.

E-mobility is not for toys and prototypes anymore. E-vehicles can range from an electric assisted bicycle, a fully electric motorbike or scooter, a fully electric car or hybrid vehicle, small electric drones and even large aircraft. ATEQ, with its technical focus and innovation culture, has found new ways to test these components for mass manufacturing.

The first basic component of every battery is a cell. A battery is a collection of cells. To keep the weight low, battery cells are frequently packaged in flexible pouches. ATEQ has developed a leak test method, patent pending, for testing these pouch cells using Ionized air technology. It allows for the testing of pouches, even without evaporating solvent.

The ionized air test can provide a leak test result for the whole pouch and it can also be used to locate the leak’s location in the cell. For metallic body cells, ATEQ also has a test method that detects the evaporation of the solvent. Each battery cell has a semi-permeable membrane that separates the battery’s plus and minus sides. This cell is flow tested prior to assembly to make sure the air flows through the membrane within the designated specifications and that there is not an unexpected hole in the membrane. Cells can be packaged together in a module with a protective envelope for easy handling.

At this stage, the module housing is generally not leak tight but sometimes a pressure decay leak test is used to test the module housing. ATEQ has a module balancer. A group of cells does not reach full charge if the cells are not at an identical charge level. The module balancer is used to even the charging level of cells during the manufacturing or maintenance process. The cells or modules are packaged together in leak tight protective housings to protect them against dust, water and mud splashing. It can be the 12 V battery of a classic internal combustion engine vehicle, a small bicycle rechargeable battery, or a fully electric vehicle car-sized battery. The leak tests all function similarly.

These battery housings and covers are tested for leaks separately before the cells/modules are mounted inside. If the housing is plastic, a differential pressure decay test with noise cancellation technology can be used to test for overall leaks in battery covers. If there is a desire to locate the defect in the cover, an ionized air leak test can be used. If the cover or tray is metal, only pressure decay technology with noise cancellation can be used. To locate leaks on a metal cover, a forming gas (H2N2) leak detection and localization with portable gas sensitive detector H6000 is the solution. ATEQ also proposes to automate this test with a smart holding robot.

Once the battery cells and modules are assembled in the housing, a final leak test needs to be performed. It can be done using a pressure decay or air mass flow technology with very low pressure drop sensors to quickly measure leaks. ATEQ’s patent pending Differential Noise Cancelling DNC technology blocks out background conditions from the leak reading. The housing typically has a semi-permeable membrane that enables the air pressure to equalize with atmospheric and temperature changes. This semi-permeable membrane lets air through, but not water.

Based on ATEQ’s experience with aviation battery testers, ATEQ can make custom battery testers that charge and discharge an entire battery.

ATEQ has an air flow tester to test the breathing patch to ensure it is not double-stacked and that it did not get poked. The tester can also perform a wet test which puts air over water to detect smaller defects at the sub-assembly level. Some batteries have a check valve instead of a breathing patch that relieves the pressure generated by any gasses emitted during charging. This check valve is tested with air pressure to look for openings, “cracking” pressure and flow using an ATEQ ERD leak tester.

Some large battery housings can be equipped with a liquid cooling circuit. The cooling circuit is also tested for leaks with an air tester. For large battery failure analysis, a forming gas sniffer can be used to locate leaks since air leak tests cannot show leak locations. Gas sniffer leak tests are also useful for troubleshooting potential leaks in a fixture. The disadvantage of using a tracer gas leak test on large batteries is that the tracer gas can take a lot of time to mix with the atmospheric air inside a battery if there is no tracer gas current across the battery. It is recommended to fully evacuate the atmospheric air from the battery tray or cover prior to pressurizing it with tracer gas since the tray/cover cannot sustain much vacuum.

It is also recommended to monitor the tracer gas concentration on multiple sealed openings in the battery to verify that the tracer gas has reached every corner of the battery.

Based on ATEQ’s experience with aviation battery testers, ATEQ can make custom battery testers that charge and discharge an entire battery. A fuel cell creates chemical energy by combining hydrogen, or any other combustible gas, with oxygen from the air and turning it into electricity for the vehicle.

The fuel side components are typically tested for leaks with a mix of 5% H2 (hydrogen) and 95% N2 (nitrogen) called forming gas. Contrary to pure hydrogen, forming gas is not flammable, and it helps detect defect areas that hydrogen could flow through. The air side is typically tested for leaks with an air pressure decay or mass flow instrument. The fuel cell’s semi-permeable membrane should be tested for air flow and the vehicle’s cooling system is leak tested with an air tester.

The upstream fuel storage and delivery systems are also tested for leaks, with air or forming gas, depending on the applications. The electric motors that operate the wheels are in leak tight housings that protect the motor against splashing water. A motor housing made of plastic can be tested using ionized air when it is not mounted. If the housing is metal, or fully assembled, it can be tested with air. The motor coil wires are coated with an insulating “varnish”. At times, this “varnish” gets cracked, mainly where the wires are bent. ATEQ has developed a test to detect this defect using ionized air technology.

The new electric vehicles also come with automated driving assistance that uses sensors to feel the environment. Whether the sensors are cameras, lidar, or something else, the sensors are in leak-tight housings since they are exposed to the elements. ATEQ also tests the TPMS sensors (Tire pressure monitoring system), during wheel and vehicle assembly and at maintenance level. An air leak test is generally preferred to test these sealed sensors.

At times, a car battery cannot sustain a fast enough charge so the energy has to be stored in a large capacitor to keep it from breaking. ATEQ has an instrument designed to safely discharge these capacitors before servicing the vehicle.

In addition to the new electric vehicle leak testing applications, it is important to remember that many of the traditional automotive air leak testing applications still exist within an e-vehicle such as: brake systems, headlights, tail lights, ABS and central computer electronics, steering components and air conditioning systems for example.

With the accelerated HEV/EV/PEV/Fuel Cell EV technology shift, OEMs must introduce new models to the market quicker than ever to stay competitive. However, this means that vehicle producers will face many new challenges during the manufacturing process such as: the increasing complexity of new vehicles, new technologies not yet fully mastered and the increased pressure to achieve the highest level of quality to avoid security risks and vehicle recalls.

To address these new challenges, ATEQ offers leak, flow, battery and TPMS testing instruments to ensure the quality testing of numerous components all throughout the EV vehicle manufacturing process.

ATEQ application engineers are familiar with existing electric vehicle leak test applications. They can also design a new leak testing solution for an application that has never been leak tested before. ATEQ has hundreds of experienced professionals who are trained in leak testing technologies. With offices and engineers all over the world, ATEQ is able to provide local assistance in developing the perfect quality testing solution for your application.