Smart Energy and Sustainable Environment , ISSN 2668-957X
2022, Volume 25, Issue 1
Pages 35-46


Nicolae Bidica * , Narcisa Ghimiş

National Research and Development Institute for Cryogenics and Isotopic Technologies - ICSI Rm. Valcea, Uzinei Street no. 4, PO Box Râureni 7, 240050, Râmnicu Vâlcea, Romania

*Corresponding author: Nicolae Bidica, E-mail:

Received 15 December 2021 Received in revised form 18 March 2022 Accepted 29 March 2022 Available online 04 April 2022
OBSERVATION: The article is presented to the 23rd International Conference “New Cryogenic and Isotope Technologies for Energy and Environment" EnergEn 2021, Baile Govora, Romania, October 26-29, 2021


Generating of very low (and well-known) gas flows meets a wide variety of needs in industry and research (especially in vacuum science and technology), but also among consumers and society (e.g: calibrations of vacuum gauges and leak detectors, leak testing to verify the tightness of many industrial products, assurance of product reliability and performance, environmental and other safety issues, and so on). So far, many methods and devices have been developed for generating very- and ultra-low flows, generally with the goal of setting flow standards for metrology. However, most of them are very complex, so that in case of certain particular research applications, new or adapted methods and devices appear to be more suitable. Such particular case is the calibration of the measurements of hydrogen isotopes permeation fluxes, when very low flows of hydrogen and/or deuterium are injected directly into the permeation cell which is operated in very different modes. This paper presents the concept of a new method proposed to accomplish this purpose, its corresponding mathematical model of flow, as well as the experiments performed to test the feasibility of the method. Briefly, the concept is based on two leaks of constant conductance through which a so-called reference flow is generated, with two stages of pressure reduction, as well as on a variable leak valve through which well-controlled flows (and over a wide range) are generated to be injected into the permeation cell.


S. Avdiaj, J. Šetina, (2017) Flowmeter for very low gas flows of inert gases, Measurement, Vol. 111, pp. 384-388.

M. Bergoglio, A. Calcatelli, G. Rumiano, (1995) Gas flowrate measurements for leak calibration, Vacuum, Vol. 46, Issues 8-10, pp. 763-765.

N. Bidica, N. Sofilca, G. Popescu, B. Monea, C. Moraru, (2020) Experimental setup and pre-experiment issues for multi-component hydrogen isotopes permeation through metals in non-steady-state, Fusion Engineering and Design, Vol. 157, pp. 1-7

L. Detian, C. Yongjun, F. Yan, (2011) Extension of the range of a constant-conductance flowmeter by a flow divider, Measurement Science and Technology, Vol. 22, No. 12, pp. 1-5.

L. Detian, C. Yongjun, F. Yan, X. Zhenhua, Z. Lan, (2013)Very low gas flow measurements for UHV/XHV and leak calibration, Metrologia, Vol. 50, pp. 15-19.

C. D. Ehrlich and J. A. Basford, (1992) Recommended practices for the calibration and use of leaks, Journal of Vacuum Science & Technology A, Vol. 10, Issue 1, pp. 1-17.

E. Hedlund and L. R. Pendrill, (2006) Improved determination of the gas flow rate for UHV and leak metrology with laser refractometry, Measurement Science and Technology, Vol. 17, No. 10, pp. 2767-2772.

M. Guo, Z. Ren, Y. Cheng, W. Sun, Y. Li, L. Zhao, M. Dong, (2019) A new high precision, broad range gas micro-flow calibration apparatus, Vacuum, Vol. 164, , pp. 428-435.

J.M. Hidalgo and J.L. de Segovia, (2008) Leak calibration by comparison with reference standard leaks, Vacuum, Vol. 82, Issue 11, pp. 1151-1156.

John F. O'Hanlon, (2003) A User's Guide to Vacuum Technology, Third Edition, John Wiley & Sons, Inc., Hoboken, New Jersey.

S. A. Tison, (1993) Experimental data and theoretical modeling of gas flows through metal capillary leaks, Vacuum, Vol. 44, No. 11 /12, pp. 1171-1175.

L. Wangkui, Z. Dixin, L. Qiang, L. Shiliang, L. Detian, M. Yang, (1996) A gas flow standard apparatus, Vacuum, Vol. 47, Issues 6-8, pp. 519-522.


very low flows of gases, leak, conductance, calibration, permeation, hydrogen

Tag search very low flows of gases leak conductance calibration permeation hydrogen