Diffusion leak artifacts as a secondary standard for gas flow

Jitschin, W.; Grosse, G.; Wandrey, D

doi:10.1016/0042-207x(88)90485-x

Cited by 9 publications

(1 citation statement)

References 10 publications

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“…To calibrate the flow rate of the standard leak with its uncertainty, information about the degrees of the stability of both the MSLD and the leaks are important. The temperature dependence [2,[4][5][6] and the depletion rate [5][6][7] of the flow rate generated by the standard leak, the linearity [7] and the stability [8], and the transition properties [8] of the reading of MSLD were investigated. In this paper, stability tests of a MSLD and standard leaks in terms of the effects of the exposure to the ambient air and the accumulated helium gas enclosed between the valve and the leak are investigated for the proper procedure of the calibration.…”

Section: Introductionmentioning

confidence: 99%

Stability tests of standard leaks for the calibration by a comparison method

et al. 2012

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Section: Introductionmentioning

confidence: 99%

Stability tests of standard leaks for the calibration by a comparison method

et al. 2012

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Stabilität der Leckrate von Helium‐Testlecks

Jitschin

1999

Vak Forsch Prax

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Zur Kalibrierung der Empfindlichkeit von Helium‐Lecksuchern werden Testlecks mit bekanntem Helium‐Gasstrom eingesetzt. Weit verbreitet ist eine Bauform von Testlecks, bei der sich das Gas in einem Reservoir befindet und mittels Permeation durch eine Wand austritt. Bei konstanter Temperatur wird ein zeitlich konstanter Leckstrom erwartet, der aufgrund des Gasverlustes allmählich geringfügig abnimmt (typisch −1% pro Jahr). Dieses Verhalten wird bei Testlecks mit Quarzglaswand auch tatsächlich beobachtet. Bei Testlecks mit Kunststoffwand treten jedoch erhebliche Schwankungen auf, die nicht verstanden sind. Ergänzend werden gemessene Reaktionszeiten der Leckrate auf Änderungen der Temperatur und des Fülldrucks für Lecks mit Quarzglaswand und mit Kunststoffwand mitgeteilt.

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Precise measurements of small gas flows—metrological basis for the calibration of leak detectors

Kuz'min¹

1997

Meas Tech

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This article discusses technical aspects of the calibration of leak detectors by using a series of artificial control flows. Results are presented from the calibration of several mass-spectrometric leak detectors. Procedures and methods of analyzing measurements obtained in the calibration of such flows are discussed, and several approaches to the metrological certification of halogen and electron-capture leak detectors are described.In the system established by the Russian Federation to metrologically certify instruments that measure gas flows, an important role is assigned to the development of methods and equipment for calibrating the instruments used to check the hermeticity of leak detectors. This problem is most important for helium mass-spectrometric leak detectors.Leak detectors are devices designed to detect leaks, i.e. disturbances in the hermeticity of vessels and joints in vacuum systems and instruments. The output signal of a leak detector generally depends on the flow of a penetrating test gas (usually helium). Thus, these instruments can be regarded as a special type of flowmeter [1, 2].Until recently, leak detectors were made commercially as indicating devices even though they were designed for use with artificial control flows. However, the metrological characteristics of these instruments (working flow range, average sensitivity, etc.) were determined only in special cases and only by indirect means. The control flows themselves were calibrated in a manner that was quite arbitrary, due to the lack of a metrologically certified master flowmeter.An analysis of the needs of different sectors of industry [3] showed that it is no longer sufficient that the leak detector be clearly sensitive to the test gas. This sensitivity must be not only not be lower than the specified values, but must also not be higher than these values. The working range of modern leak detectors must also be broad enough to meet the needs of the customer (generally, this range goes from 10-t2-10-t~ to 10-5-10 -4 m3-pa/sec). Finally, leak detectors must meet all of the normal requirements established for measuring instruments. All this led the D. I. Mendeleev All-Union Scientific Research Institute of Metrology (VNIIM) (in St. Petersburg) to formulate the problem in a new way and develop a master flowmeter for the calibration of leak detectors and artificial flows [4, 5]. Certain leak detectors can be calibrated by comparing them directly with the master flowmeter. However, this approach is not always feasible or expedient in practice. A simpler and more convenient method is to calibrate leak detectors on the basis of sets of standard measures of gas flow -thermostatted artificial flows. CALIBRATION OF STANDARD FLOWSEvery artificial flow can be calibrated at a fixed temperature in order to make it an unambiguous (or multivalued) measure of the flow of a test gas. The flow is assumed to be constant within certain limits (such as 10-20%) over a certain time interval AT" (see below). Assuming that certain conditions related to the...

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Diffusion leak artifacts as a secondary standard for gas flow

Cited by 9 publications

References 10 publications

Stability tests of standard leaks for the calibration by a comparison method

Stability tests of standard leaks for the calibration by a comparison method

Stabilität der Leckrate von Helium‐Testlecks

Precise measurements of small gas flows—metrological basis for the calibration of leak detectors

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