HeMaTech Prüftechnik GmbH & Co. KG
Differential pressure testing
Detect Leaks with Precision
Precise Leak Testing for Industrial Applications
Differential pressure testing is one of the most proven methods of industrial leak testing. In mass production in particular, it is used wherever components must be reliably tested for leaks and where high standards of accuracy, reproducibility, and cost-effectiveness are required.
Compared to other testing methods, differential pressure testing offers very high measurement accuracy and minimizes the influence of external factors such as temperature fluctuations. This makes it suitable for numerous industrial applications and allows it to be easily integrated into automated manufacturing processes. The following content is based on the technical description of the method provided.
Compared to other testing methods, differential pressure testing offers very high measurement accuracy and minimizes the influence of external factors such as temperature fluctuations. This makes it suitable for numerous industrial applications and allows it to be easily integrated into automated manufacturing processes. The following content is based on the technical description of the method provided.
Measuring Pressure Differences with Precision
What is a differential pressure test?
Differential pressure testing is a method used to test components for leaks. The measurement principle is based on comparing the pressure inside the test specimen with that in a reference volume or a reference body.
During the measurement, even the smallest pressure differences are detected. If air escapes from the test specimen due to a leak, a differential pressure develops between the test specimen and the reference volume. This pressure difference is measured and used to assess the tightness of the specimen.
The method is particularly suitable for applications with higher requirements for measurement accuracy and is frequently used in industrial quality testing.
During the measurement, even the smallest pressure differences are detected. If air escapes from the test specimen due to a leak, a differential pressure develops between the test specimen and the reference volume. This pressure difference is measured and used to assess the tightness of the specimen.
The method is particularly suitable for applications with higher requirements for measurement accuracy and is frequently used in industrial quality testing.
Compare Reference Pressure
How does differential pressure measurement work?
Unlike methods that monitor only the pressure within the test specimen, the differential pressure test uses an additional reference volume.
Depending on the application, the following can be used for this purpose:
Depending on the application, the following can be used for this purpose:
Particularly when dealing with larger test volumes or elastic test specimens, the use of a suitable reference volume can significantly improve measurement accuracy.
To ensure reliable measurement results, both the measurement system and the test fixture itself must be leak-tight. Only under identical test conditions can the smallest pressure differences be unequivocally attributed to a leak in the test specimen.
To ensure reliable measurement results, both the measurement system and the test fixture itself must be leak-tight. Only under identical test conditions can the smallest pressure differences be unequivocally attributed to a leak in the test specimen.
Four testing phases
Procedure for a Differential Pressure Test
A differential pressure test is generally divided into four consecutive phases.
Build up test pressure
1. Filling Phase
At the start, both the test specimen and the reference volume are pressurized simultaneously.
Both volumes reach the same test pressure. At the same time, the differential pressure sensor is protected from excessive pressure loads.
Both volumes reach the same test pressure. At the same time, the differential pressure sensor is protected from excessive pressure loads.
Stabilize the system
2. Stabilization Phase
Filling is followed by the equilibration phase.
During this time, the pressure and temperature within the system can stabilize. The goal is to create uniform initial conditions for the actual measurement and to minimize the influence of physical disturbances as much as possible.
During this time, the pressure and temperature within the system can stabilize. The goal is to create uniform initial conditions for the actual measurement and to minimize the influence of physical disturbances as much as possible.
Identify a Leak
3. Measurement Phase
For the actual measurement, the test specimen and the reference volume are separated from one another. If the test specimen is leak-tight, the pressure difference between the two volumes remains nearly constant.
If, on the other hand, there is a leak, the pressure in the test specimen changes. The resulting differential pressure is recorded and evaluated by the measurement system. In this way, even very small leaks can be reliably detected.
If, on the other hand, there is a leak, the pressure in the test specimen changes. The resulting differential pressure is recorded and evaluated by the measurement system. In this way, even very small leaks can be reliably detected.
Complete the exam
4. Venting
Once the measurement is complete, the test pressure is gradually released.
The next test cycle can then be started.
The next test cycle can then be started.
Various Measurement Principles
Measurement Procedures for Differential Pressure Testing
Depending on the test task, different measurement systems can be used.
Simple Measurement Principle
Measurement Using a Pressure Sensor
Compare Two Pressures
Measurement Using Two Pressure Sensors
Highest Measurement Accuracy
Measurement Using a Differential Pressure Sensor
In this variant, the pressure inside the test specimen is measured using a single pressure sensor. The measurement is based on absolute or relative pressure.
Here, both the test specimen and the reference volume are monitored by their own pressure sensors.
By comparing the two pressure readings, the leak tightness of the test specimen can be assessed.
The most precise version uses a differential pressure sensor.
In this design, two chambers are separated from each other by a diaphragm. Even the smallest pressure differences cause the diaphragm to move, allowing for highly precise measurements.
This measuring principle forms the basis of modern differential pressure testers.
In this design, two chambers are separated from each other by a diaphragm. Even the smallest pressure differences cause the diaphragm to move, allowing for highly precise measurements.
This measuring principle forms the basis of modern differential pressure testers.
Alternative Testing Methods
The Hood and Bell Method
For certain applications, the differential pressure test can also be combined with a hood or bell method.
Depending on the test requirements, the test is performed using either an overpressure or a vacuum method. The measurement principle is also based on comparing pressure ratios and enables a reliable assessment of leak tightness.
Depending on the test requirements, the test is performed using either an overpressure or a vacuum method. The measurement principle is also based on comparing pressure ratios and enables a reliable assessment of leak tightness.
Precise and cost-effective
Advantages of Differential Pressure Testing
Differential pressure testing offers a number of advantages for industrial testing processes:
As a result, this process is one of the most commonly used methods for industrial leak testing.
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A Wide Range of Applications
Typical Applications
Differential pressure testing is suitable for a wide variety of components and industries.
The specific test method used in each case depends on factors such as component geometry, test volume, permissible leakage, and the requirements of the test process.
Submit a Request NowThe specific test method used in each case depends on factors such as component geometry, test volume, permissible leakage, and the requirements of the test process.
Typical applications include, among others:
Expertise Based on Experience
Why HeMaTech?
HeMaTech helps companies select and implement suitable solutions for industrial leak testing.
Its range of services includes, among other things:
Its range of services includes, among other things:
Leak Testing Instruments
Learn MoreLeak Testing Systems
Learn MoreFlow Measurement Technology
Learn MoreIntegration into automated production lines
Learn MoreAdvice on Selecting the Appropriate Test Method
Learn MoreThe combination of testing technology and automation results in cost-effective solutions that are precisely tailored to the specific testing task.
Personalized advice
The Right Solution for Your Leak Test
Each testing task has different requirements in terms of accuracy, testing time, and cost-effectiveness. We’ll work with you to develop the right solution—from selecting the appropriate differential pressure method to integrating it into your existing production process.
Do you have questions about differential pressure testing, or wouldyoulike to reliably test your components for leaks?
Contact us—we’d be happy to advise you personally.
Do you have questions about differential pressure testing, or wouldyoulike to reliably test your components for leaks?
Contact us—we’d be happy to advise you personally.
HeMaTech Prüftechnik GmbH & Co. KG
Siemensstr. 7
D-71409 Schwaikheim
FAQ on Leak Testing
Frequently Asked Questions
What is a differential pressure test?
A differential pressure test is a leak testing method in which the pressure in the test specimen is compared to that in a reference volume in order to reliably detect leaks.
When is a differential pressure test used?
This method is particularly well-suited for industrial applications with high requirements for measurement accuracy, reproducibility, and process reliability.
What are the advantages of differential pressure testing?
Among the most important advantages are high measurement accuracy, minimal temperature effects, reproducible results, and suitability for automated batch testing.
What is a reference volume?
The reference volume serves as a reference volume during the measurement. It can be designed as an internal reference vessel or as a reference block and improves the accuracy of the differential pressure measurement.
For which components is this process suitable?
Differential pressure testing is used for valves, housings, piping, plastic components, and other hollow bodies, among other things.