Leak Tester / Measurement procedures

We will asses your individual test situation and configure the leak-measurement computer LTC 602 on the basis of the required task setting. As a service we offer test measurements and initial samplings in our laboratory.

Index of contents / Test methods with compressed air 1. Differential pressure measurement procedure   1.1 Pressure dropping-/ decrease measurement procedure 1.1.1 Absolute pressure measurement procedure LTC-602 A 1.1.2 Relative pressure measurement procedure LTC-602 R 1.1.3 Dosing measurement procedure LTC-602 D 2.1 Pressure increase measurement procedure LTC-602 S 3. Mass flow measurement procedure with reference LTC-602 M 4. Flow measurement LTC-602 Q

[ Picure enlarge ] 1.1.1 Absolute pressure measurement procedure with Leak Tester LTC-602 A The pressure dropping /pressure decrease procedure is by far the most used procedure in leak testing.. Test medium: Compressed air / vacuum, nitrogen, hydrogen, helium Observable leak rates: volume and pressure dependent > 1 cm3/min Method: The sample will be charged with pressure. The pressure change (pressure drop) caused by leakages, will be measured and evaluated. Advantages: simple, quick and cost efficient method a small number of tools little demand of operation and maintenance personnel automated test sequence available evaluation independent of the operator Disadvantages: Usable pressure differential resolution depends on pressure and volume. Thermical and elastic modifications of the sample affect the measuring result, usually not applicable for leak rates < 1 cm3 / min

[ Picture enlarge ] 1.1.2 Relative pressure measurement procedure with Leak Tester LTC-602 R The pressure decrease procedure is by far the most used procedure in leak testing. Test medium: Compressed air / vacuum, nitrogen, hydrogen, helium Observable leak rates: volume and pressure dependent > 1 cm3/min In case of small volumes even < 1 cm3 / min Method: The sample will be charged with pressure. The pressure change in the sample caused by leakage, will be measured and evaluated against an internal reference through a transmitter. Advantage: same features as the absolute pressure measurement procedure good measuring signal resolution, even at a high test pressure the reference volume for elastic parts is also advantageous, because the volume dilatation is better compensated for. where required, external reference for complex or elastic parts   Disadvantage: a bit more complex because of the use of an extra pressure difference sensor, that measures against a difference unsuitable for high pressure drops or burst tests

[ Picture enlarge ] 1.1.3 Dosing procedure with Leak Tester LTC 602 D Pressure dropping /pressure decrease procedure with volume determination for closed components testing or for volume determination Test medium: Compressed air / vacuum, nitrogen Observable leak rates: volume and pressure dependent > 1 cm3/min Observable volume differences Prefilling volume > 2-3 %, depends on sample volume / referenz ratio Method A known pre-filling volume is charged with pressure / vacuum and then stabilized. Afterwards this gas volume is led into the sample or the test chamber. The appearing pressure is a measurement for the volume. The additional pressure change that develops through leakage is measured and evaluated.  Characteristics: Simple and cost-efficient procedure Volume determination, testing of closed components is possible

[ Picture enlarge ] 2.1. Pressure increase procedure with Leak tester LTC 602 S Test medium: Compressed air / vacuum, nitrogen Test pressures up to 500 bar possible Observable leak rates: volume and pressure dependent > 0,1 cm3/min Method: The samples are charged with pressure / vacuum. The pressure change that develops through leakage in the cover surrounding the sample, is measures and evaluated. Sometimes this method is performed in combination with a pressure decrease prcedure (for ex. for oil coolers) Advantage: possibility of choosing any high test pressure (up to 500 bar) very fast testing procedure because there is no slow-down phase small leak rates up to 0,1 Ncm3 / min possible evaluation independent of the operator Disadvantage: often there is a high mechanical effort required, due to the use of a volume optimized test cover. Through the cover, the sample and the adaption are only visible to a certain extent A leaky cover can lead to incorrect results The test chamber also has to be charged with slight overpressure or low-pressure in order to identify leakage of the chamber.

[ Picture enlarge ] 3. Flow testing procedure with reference with Leak Tester LTC 602 M Test medium: Compressed air / vacuum, nitrogen Observable leak rates: volume and pressure dependent > 0,5 cm3 / min Method: The sample is charged with pressure / vacuum. The air that is released due to leakage is leveled by a reference volume. The equalizing current is determined by a mass flow gauger and is a measurement for the leak rate. Advantage: even when there are large volumes, small leak rates of less than a few Ncm3 / min can be measured. Possibility of a short measuring period, because the response time of the mass flow < 1 sec small leak rates of less than 0,1 Ncm³ / min possible Disadvantage: more work in the measuring device due to the required reference volume the ratio of reference volume to sample volume should not exceed 5:1

Bild vergrößern 4. Flow measuring device / Leak tester LTC 602 Q The flow measuring device LTC 602 Q is a measurement computer for measuring the flow of gases. The device is avaiable in different pressure ranges and with different flow measuring ranges. Test medium: Compressed air, nitrogen, special models for water, additional models upon request Test pressures: different measuring ranges, continuous from 0,1 to 20 bar Flow measuring range: 1,5 – 50 ml/min, resolution 0,5 ml/in at high performance resolution. Flow range up 400 Nl/min, special models can be even higher

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