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Leak test methodology (measuring, testing and practical use)

Principle and methodology of dry air leak test whether it is standard or complex design testing environmental system

Following dry air leak test methods are widely used for production and development purposes that has a concern of actual media leakage in automobile and general industry applications. TeSys is representing JW Froehlich GmbH in long term based partnership for leak test technology and measurement panel products with local engineering support and services, including repair and calibration capability in the near future.


Relative Pressure Measurement (Standard pressure decay)

In the relative pressure method, the test part is pressurized with air and the pressure sensor is used to detect any leakage following the balancing phase.

As the pressure sensor is only pressurized on one side, the test pressure which can be applied is limited. The relative pressure method is used for smaller

test volumes and when sufficient test time is available, and is favored for its cost effectiveness.

  • Compact and cost effective design
  • Small intrinsic test volume with sufficient test time
  • Large measuring range - JW Froehlich leak test panels
  • Applicable leak test panel products: MPS100/200/300/400/500

Differential Pressure Measurement (High-resolution pressure decay)

In the differential pressure method, the test part is pressurized with air and the differential pressure sensor is used to detect any leakage following the balancing phase.

As this sensor is pressurized on two sides, high test pressures of up to 20 bar can be achieved, delivering very fine measurement resolutions.

The differential pressure method is thus preferred for high pressures and low allowable leak rates.


  • High test pressure up to 20 bars
  • High resolution independent of test pressure (low leak rate even at high test pressure)
  • Testing of unstable parts by using original reference part
  • Applicable leak test panel products: MPS150/250/350/450/550

Mass-flow Measurement (Standard range)

The first step of the mass flow method is to fill a reference volume VEX with test air. This is then used to fill the test part and achieve the test pressure.

Unlike the pressure decay method, the mass flow sensor delivers immediate measurement results in the event of a leakage, which makes it the most suitable method for high-volume parts and short cycle times.


  • Instantaneous measuring signals by mass flow sensor
  • Test signal independent to test volume and pressure
  • Measuring large test volume from 500ml
  • Shorter test time compared to pressure measurement
  • Test signal correspondent to leak rate in standard condition
  • Applicable leak test panel products: MFL200/300/400/500

Mass-flow Measurement (Wide range)

The high-range measuring method is used when high allowable leak rates

(> 500 cm3/min) are required. The measuring circuit is designed in such a way that large air flows can be detected as mass flows at a constant test pressure.

  • Measuring technology for high leak rates
  • Measuring signal independent of test volume and test pressure
  • Measuring signal corresponds to leak rate in normal conditions
  • Exceptionally reproducible measurement results
  • Applicable leak test panel products: MFL260/360/460/560


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