New method of a constant-pressure flowmeter traceability

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00177016%3A_____%2F23%3AN0000091" target="_blank" >RIV/00177016:_____/23:N0000091 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.nist.gov/system/files/documents/noindex/2023/05/22/CCM%20Program%20Book.pdf" target="_blank" >https://www.nist.gov/system/files/documents/noindex/2023/05/22/CCM%20Program%20Book.pdf</a>

DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

New method of a constant-pressure flowmeter traceability

Popis výsledku v původním jazyce

Czech Metrology Institute covers the range of high vacuum by a primary standard based on the orifice-flow (also continuous or dynamic expansion) principle. A continuous and precisely determined gas throughput is admitted into a calibration chamber, which is pumped through a precise orifice by a known pumping speed. The calibration pressure in the chamber can be calculated as their ratio. The gas throughput must be generated by means of a suitable primary gas flowmeter. In our case, the utilization of two constant pressure flowmeters (CPF) was necessary to cover the entire demanded range of the generated pressures. Volume displacers of both flowmeters are based on directly compressed welded bellows (consisting of the welded metal foil annuli), each compressed by a screw driven by a step motor. After a fatal leakage had occurred in one CPF, the leaky welded below has been replaced with an identical one. Of course, its pressure-compression dependence of displaced volume had to be calibrated. On this occasion, the quicker calibration method has been developed. The new method utilizes a very slow but constant displacement of the piston with a tied-up but discontinuous volume-change of the bellow. Thus, a several times shorter calibration time can be achieved with the same or slightly lower uncertainty of the volume-change.

Název v anglickém jazyce

New method of a constant-pressure flowmeter traceability

Popis výsledku anglicky

Czech Metrology Institute covers the range of high vacuum by a primary standard based on the orifice-flow (also continuous or dynamic expansion) principle. A continuous and precisely determined gas throughput is admitted into a calibration chamber, which is pumped through a precise orifice by a known pumping speed. The calibration pressure in the chamber can be calculated as their ratio. The gas throughput must be generated by means of a suitable primary gas flowmeter. In our case, the utilization of two constant pressure flowmeters (CPF) was necessary to cover the entire demanded range of the generated pressures. Volume displacers of both flowmeters are based on directly compressed welded bellows (consisting of the welded metal foil annuli), each compressed by a screw driven by a step motor. After a fatal leakage had occurred in one CPF, the leaky welded below has been replaced with an identical one. Of course, its pressure-compression dependence of displaced volume had to be calibrated. On this occasion, the quicker calibration method has been developed. The new method utilizes a very slow but constant displacement of the piston with a tied-up but discontinuous volume-change of the bellow. Thus, a several times shorter calibration time can be achieved with the same or slightly lower uncertainty of the volume-change.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

20205 - Automation and control systems

Projekt

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Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů