In order to be able to assess whether a fitting meets the airtightness requirement, measurements must be taken. The principle of measurement is basically the same as for measurements on air ducts. A standard test rig is required for measurements on the single fittings. This test setup looks like the one shown next to the text. For the Luka Quality Certificate Luka members require measurement reports from suppliers of fittings or information through the Luka Fitting Register, the "LAR", to be able to assess whether the projected fittings satisfy the airtightness requirement imposed. Measurements must have been carried out by a measurement institute with a quality system according to ISO 17025. The international or national accreditation body of this measurement institute must be recognized and affiliated to the EA or MLA. Please refer to the website of the Dutch Accreditation Council for more information on accreditation. The Luka members also accept their own measurement reports from suppliers of fittings, provided these suppliers have a valid TÜV Rheinland Measuring Label.

There are three European standards relating to the measurement of air density for fittings:

• NEN-EN 1751; applicable to valve registers and control and/or shut-off valves
• NEN-EN 13180; applicable to flexible hoses
• NEN-EN 15727; applicable to other fittings (only measured on overpressure)