CEN/TC 138/WG 6 - Leak testing

ISO 20485:2017 describes the techniques to be applied for the detection of a leak, using a tracer gas and a tracer gas specific leak detector.

ISO 20486:2017 specifies the calibration of those leaks that are used for the adjustment of leak detectors for the determination of leakage rate in everyday use. One type of calibration method is a comparison with a reference leak. In this way, the leaks used for routine use become traceable to a primary standard. In other calibration methods, the value of vapour pressure was measured directly or calculated over a known volume.
The comparison procedures are preferably applicable to helium leaks, because this test gas can be selectively measured by a mass spectrometer leak detector (MSLD) (the definition of MSLD is given in ISO 20484).
Calibration by comparison (see methods A, As, B and Bs below) with known reference leaks is easily possible for leaks with reservoir and leakage rates below 10−7 Pa·m3/s.
Figure 1 gives an overview of the different recommended calibration methods.

ISO 20484:2017 defines the terms used in leak testing.

This European Standard specifies criteria for the selection of equipment for the leak detection methods described in EN 1779. The minimum requirements for the performance of the instruments used are also given as a guideline for personnel involved in testing. The definite selection of an instrument for a given test is within the responsibility of a qualified operator (at minimum level 2 qualification - see EN 473).

This standard describes the techniques for the determination of the rate of leakage across the boundary of an isolated object, subjected to a pressure difference. The techniques are based on the evaluation of the change of the mass of gas within the test object. The ideal gas equation states the relationship between mass, pressure, temperature and volume of the gas contained in the internal free volume of the object. In some circumstances one or more variables may be considered constant and so the mass change can, for example, be assessed by monitoring the pressure or pressure-temperature changes within the test object.

This European Standard describes procedures for the detection and location of leaks by the bubble emission techniques. The sensitivity depends on techniques and materials used.  Two techniques are described:  a)  immersion technique: quantitative measurements can be made using this procedure with particular devices (see informative annex A); b)  liquid application technique.  This standard can be used for equipment which can be evacuated or pressurised.

This European Standard describes criteria for the selection of the most suitable method and technique for the assessment of leak tightness by indication or measurement of a gas leakage. Annex A, normative, allows a comparison of standard test methods. Leak detection using hydrostatic tests, ultrasonic or electromagnetic methods is not included in this document.  This standard can be used for equipment which can be evacuated or pressurized.

This European Standard specifies terms and procedures for the characterization of mass spectrometer leak detectors (MSLD). It is not intended to give a complete set of specifications for an acceptance test but a description of procedures that can be used without particular calibration equipment.  An MSLD has an integral high vacuum system for maintaining the sensing element (mass spectrometer) at low operating pressure and for establishing a partial pressure related to the incoming gas flow.

This draft European Standard specifies the calibration of those leaks that are used for the adjustment of leak detectors for the determination of leakage rate in everyday use. The preferred calibration method in this case is a comparison with a standard leak. In this way the leaks used for routine use become traceable to a primary standard as the ISO 9000 series of standards require.
The comparison procedures are preferably applicable to helium leaks, because this test gas can be selectively measured by a mass spectrometer leak detector (MSLD) (the definition of MLSD is given in EN 1330-8).
Calibration by comparison (see methods A and B below) with known standard leaks is easily possible for leaks with reservoir and leakage rates below 10-7Pa·m3/s.
From 10-7 Pa·m3/s to 10-4 Pa·m3/s no leaks reliable enough to be used as transfer standard exist. Leaks in this range can only be calibrated by measurement of flow in a calibrated capillary tube (see method C below).
Leakage rates greater than 10-4 Pa·m3/s can be measured by flow meters calibrated against primary national standards.

This standard describes the techniques to be applied for the detection of a leak, using a tracer gas and a tracer gas specific leak detector.

This European Standard defines the terms used in leak testing.