Leak testing dictionary<\/p>\n<\/h1>\n
Brief explanations for important terms<\/p>\n<\/h2>\n
What is a leak calibrator and what exactly does absolute pressure mean? At what stage in the testing process is the filling phase and what are the parameters of a gas flow rate?<\/p>\n
We provide brief explanations for the most important terms in our leak testing dictionary. Have fun learning!<\/p>\n<\/div>\n
(Symbol p; unit Pa)<\/p>\n
The pressure relative to empty space. Absolutely empty space defines the pressure zero point.<\/p>\n
[According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n
A measuring device that measures the absolute pressure.<\/p>\n
[According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n
A leak testing method in which the component is placed in a sealed volume and then subject to tracer gas. A measuring device then measures the temporal concentration increase in this volume, which is caused by the leak in the component.<\/p>\n
[According to EN 1330-8]<\/p>\n<\/div>\n<\/div>\n<\/li>\n
A conductance leak having a diameter much greater than the leakage path length.<\/p>\n
NOTE: It may be considered an opening in a very thin wall.<\/p>\n
[According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n
See Virtual leak<\/a><\/p>\n<\/div>\n<\/li>\n The pressure of the atmosphere at a specified time and place.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n<\/ul>\n See Bombing<\/p>\n<\/div>\n<\/li>\n In the case of a leak test using a pressure change method, the balancing phase gives the system the necessary time to minimize undesirable contributions to the pressure change that result from an effective leak. Typical disruptive factors are the thermal effects due to inhomogeneity of the temperature in the gas and the test object and physical effects due to evaporation or condensation of vapors in the test object. The duration of the balancing phase is heavily dependent on the test object and the ambient conditions and is usually calculated empirically.<\/p>\n<\/div>\n<\/li>\n See Tight chamber<\/a><\/p>\n<\/div>\n<\/li>\n Bell testing during leak testing with air<\/p>\n The meaning of the term bell testing in the context of leak testing with air is explained under the leak testing method.<\/p>\n Bell testing during tracer gas leak detection<\/p>\n An integral test in which the test object is placed in a soft enclosure at atmospheric pressure.<\/p>\n NOTE 1: If the test object is under vacuum, the enclosure is filled with tracer gas and the leak detector is connected to the inner volume of the object.<\/p>\n NOTE 2: If the test object is pressurized with the tracer gas, the leak detector is connected to the enclosure\/bell.<\/p>\n A gas sniffer or a gas detector (He \/ H2) can be used as the leak detector.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n A test in which sealed test objects are subject to a back pressurizing process prior to testing them in a vacuum chamber.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n See Bubble testing<\/p>\n<\/div>\n<\/li>\n A leak testing method in which leaks from test objects subject to excess pressure can be found by completely immersing them in a test liquid (water) or by covering their surface with a surfactant solution (foaming agent). The pressure in the test object is therefore high enough to indicate leaks by bubble formation.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n<\/ul>\n Calibration in general and in leak testing with air<\/p>\n Refers to the measurement and documentation of the deviation of a measuring device test compared to a traceable standard.<\/p>\n Calibration of a mass spectrometric leak detector:<\/p>\n The setting of the sensitivity or calibration factor of a leak detector so that the display change is equal to the leakage rate of a test leak.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n See Balancing phase<\/a><\/p>\n<\/div>\n<\/li>\n Conductance leak where the diameter is small in relation to the length.<\/p>\n<\/div>\n<\/li>\n This can mean both bell testing and the accumulation testing.<\/p>\n Also see Bell testing<\/a> (symbol nB)<\/p>\n The ratio of the number of atoms or molecules of a given constituent to the total number of atoms or molecules in a mixture. For gases, this ratio is equivalent to the volume fraction (symbol c).<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n A leak which consists of one or more discrete openings, including porous areas, through which a fluid may flow.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n A mass spectrometric leak detector where the tracer gas enters through the backing line into the outlet of the high vacuum pump and the partial pressure of the tracer gas is measured on the high vacuum side of this pump.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n<\/ul>\n The volume of the leak testing system added to the volume of the test object.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n See Minimum detectable leakage rate<\/a><\/p>\n<\/div>\n<\/li>\n A mass spectrometric leak detector where the gas from the inlet line enters through the high vacuum pump and the partial pressure of tracer gas is measured on the high vacuum side of this pump.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n<\/ul>\n The pressure displayed by a pressure gauge that measures relative to atmospheric pressure.<\/p>\n [According to EN 1330-8]<\/p>\n Also see Relative pressure<\/a><\/p>\n<\/div>\n<\/div>\n See Filling phase<\/p>\n<\/div>\n<\/div>\n<\/li>\n In this phase, the test object is filled to a pressure level equivalent to the test pressure. The duration of the filling process (filling time) is dependent on the volume of the test object and the pressure value.<\/p>\n The filling phase can be preceded by a pre-filling phase. This preparation phase is intended to pre-stress and mechanically stabilize the test object and to minimize the thermal effects in the tracer gas. Duration and pressure value are calculated empirically. Typically, the pre-filling pressure is 10\u201320% higher than the filling pressure.<\/p>\n<\/div>\n<\/li>\n The pressure at which the measurement is executed. This is typically specified as relative pressure<\/p>\n See Relative pressure<\/a> See Filling phase<\/p>\n<\/div>\n<\/li>\n (For gas flow through a line, part of a line, or an orifice) (symbol C, U; unit m3\/s): The quotient of the pV throughput and the difference in the pressures prevailing at two specified cross sections or at either side of an orifice, assuming temperature uniformity in the system.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n<\/ul>\n The property of a non-porous material to allow gas to pass through under a partial pressure difference by a process of solution\/diffusion.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n (Mass: Symbol qM; unit kg\/s<\/p>\n Particles: Symbol qN; unit s\/1<\/p>\n Molar: Symbol qv; unit mol\/s)<\/p>\n The rate at which a quantity of gas passes through a given cross section of the system. The flow rate is given as the number of moles, the mass, or the number of particles moving per unit of time.<\/p>\n The flow rate is expressed in moles per second, kilograms per second, or 1\/second (for particles).<\/p>\n For gases, the volume flow rate (volume: Symbol qV; unit m3\/s) is a measure of quantity only under specified conditions.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n<\/ul>\n Leak detector that responds to helium (4He) tracer gas.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/div>\n The ideal gas in physics and physical chemistry is an idealized model of a real gas that precisely fulfills the relationship pV=nRT<\/p>\n where: See Integral leakage rate<\/p>\n<\/div>\n<\/li>\n The sum of all leakage rates from all leaks in an object, expressed as pV throughput.<\/p>\n [According to EN 1330-8]<\/p>\n<\/div>\n<\/li>\n A leak test which allows the integral leakage rate of a component to be determined. Integral testing methods include the pressure change test, the accumulation test, and the vacuum test.<\/p>\n<\/div>\n<\/li>\n<\/ul>\n In non-destructive test technology, a hole, porosity, permeable element, or other structure in the wall of a test object capable of passing gas from one side of the wall to the other due to a pressure or concentration difference.<\/p>\n [According to EN 1330-8]<\/p>\n Also see Leakage rateAtmospheric pressure<\/h3>\n
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Back pressurizing test<\/h3>\n
Balancing phase<\/h3>\n
Bell<\/h3>\n
Bell testing<\/h3>\n
Bombing<\/h3>\n
Bubble test<\/h3>\n
Bubble testing<\/h3>\n
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Calibration<\/h3>\n
Calming phase<\/h3>\n
Capillary leak<\/h3>\n
Chamber test<\/h3>\n
Also see Accumulation testing<\/a><\/p>\n<\/div>\n<\/li>\nConcentration<\/h3>\n
Conductance leak<\/h3>\n
Counterflow leak detector<\/h3>\n
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Dead volume<\/h3>\n
Detection limit of a leak test<\/h3>\n
Direct flow leak detector<\/h3>\n
Excess pressure<\/h3>\n
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Filling<\/h3>\n
Filling phase<\/h3>\n
Filling pressure<\/h3>\n
See Filling phase<\/p>\n<\/div>\n<\/li>\nFilling time<\/h3>\n
Flow conductance<\/h3>\n
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Gas permeability<\/h3>\n
Gas flow rate<\/h3>\n
Helium leak detector<\/h3>\n
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Ideal gas<\/h3>\n
n = m\/M;
p = pressure;
V = volume;
m = mass of the gas;
M = molecular mass;
R = universal gas constant;
T = absolute temperature.<\/p>\n<\/div>\n<\/li>\nIntegral leak<\/h3>\n
Integral leakage rate<\/h3>\n
Integral test<\/h3>\n
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Leak<\/h3>\n
Also see pV throughput<\/a><\/p>\n<\/div>\n<\/li>\nLeak calibrator<\/h3>\n