Verification of Gas Flow Traceability from 0.1 sccm to 1 sccm Using a Piston Gauge

NCSLI Measure ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 10-16
Author(s):  
Michael Bair
Keyword(s):  
Laminar Flow ◽  
Gas Flow ◽  
Vertical Displacement ◽  
Pressure Control ◽  
Effective Area ◽  
Flow Measurements ◽  
Piston Cylinder ◽  
Measurement Assurance ◽  
Piston Gauge ◽  
Means Of Measurement

Fluke Calibration is accredited for gas flow measurements in the range of 0.1 sccm to 6000 slm in nitrogen and air. Traceability is maintained directly through a gravimetric f low standard but only recently from 1 sccm to 10 sccm. The traceability of flow in the range of 0.1 sccm to 1 sccm is based on extrapolation of the use of laminar flow elements (LFE) below 1 sccm. This part of the range has never been completely verified through interlaboratory comparisons, proficiency testing or other means of measurement assurance. In an internal document from DH Instruments in the early 1990s it was suggested that a piston gauge might improve traceability for very low gas flows. In order to prove out traceability in this range an attempt was made to use a piston gauge using a piston-cylinder size of 35 mm diameter as a reference. One reason for choosing a piston gauge as a reference is its pressure control. This is crucial when measuring gas flow through a LFE in this design and range. In addition, the effective area is known to within 0.001 %, leaving the vertical displacement of the piston to dominate the uncertainty of the dimensional part of the flow test. This was a challenge because the measurements required absolute mode and the internal piston position sensor supplied with the piston gauge did not have sufficient precision. This paper describes the theory and design of the gas flow measurement system, the current results, and improvements desired or suggested. Two different designs are discussed, one with a single piston gauge as a reference and one with two piston gauges measuring flow on either side of the laminar flow element. Note: sccm (standard cubic centimeters per minute) is an industry accepted alternative to kg/s [1]. It is used out of convenience to normalize flow rates of gases with significant differences in density.

scholarly journals Validation of a PTB force-balanced piston gauge primary pressure standard

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 271
Author(s):  
Ahmed Salama Hashad ◽  
Wladimir Sabuga ◽  
Sven Ehlers ◽  
Thomas Bock
Keyword(s):  
Gas Flow ◽  
Rarefied Gas ◽  
Operation Mode ◽  
Experimental Methods ◽  
Effective Area ◽  
Standard Uncertainty ◽  
Operating Pressure ◽  
Pressure Balance ◽  
Piston Gauge ◽  
Relative Standard

Experimental methods using different pressure standards were applied to verify theoretical results obtained for the effective area of the piston-cylinder assembly (PCA) and for pressures measured with a force-balanced piston gauge (FPG). The theoretical effective area was based on the PCA’s dimensional properties defined via diameter, straightness and roundness measurements of the piston and cylinder, derived by gas-flow modelling using principles of the rarefied gas dynamics, and presented as two values: one obtained for absolute and the other for gauge pressure operation mode. Both values have a relative standard uncertainty of 5×10<sup>-6</sup>. The experimental methods chosen were designed to cover the entire operating pressure range of the FPG from 3 Pa to 15 kPa. Comparisons of the FPG with three different PTB pressure standards operated in different pressure ranges – a pressure balance, a mercury manometer and a static expansion system – were performed using the cross-float method and by a direct comparison of the generated pressures. For the theoretical and experimental effective area, as well as for pressures generated by the FPG and the reference standards, all the results demonstrated full agreement within the expanded uncertainties of the standards.

Evaluation of effective area of air piston gauge with limitations in piston-cylinder dimension measurements

Metrologia ◽  
2021 ◽  
Author(s):  
Vikas Narayan Thakur ◽  
Felix Sharipov ◽  
Yuanchao Yang ◽  
Sandeep Kumar ◽  
Jokhan Ram ◽  
...  
Keyword(s):  
Effective Area ◽  
Piston Cylinder ◽  
Piston Gauge

scholarly journals Rarefied gas flow in pressure and vacuum measurements

ACTA IMEKO ◽  
2014 ◽  
Vol 3 (2) ◽  
pp. 60 ◽  
Author(s):  
Jeerasak Pitakarnnop
Keyword(s):  
Gas Flow ◽  
Rarefied Gas ◽  
Slip Flow ◽  
Effective Area ◽  
Low Flow ◽  
Vacuum System ◽  
Rarefied Gas Flow ◽  
Pressure Balance ◽  
Piston Cylinder ◽  
Flow Leak

Flows of a gas through the piston-cylinder gap of a gas-operated pressure balance and in a general vacuum system have one aspect in common, namely that the gas is rarefied due, respectively, to the small dimensions and the low pressure. The flows in both systems could be characterised as being in either slip-flow or transition regimes. Therefore, fundamental research of flow in these regimes is useful for both pressure and vacuum metrology, especially for the gas-operated pressure balance where a continuum viscous flow model is widely used for determining the effective area of the pressure balance. The consideration of gas flow using the most suitable assumption would improve the accuracy of such a calculation. Moreover, knowledge about rarefied gas flow will enable gas behaviour in vacuum and low-flow leak detection systems to be predicted. This paper provides useful information about rarefied gas flow in both slip-flow and transition regimes.

scholarly journals Establishment of air piston gauge as primary pressure standard at CSIR-National Physical Laboratory INDIA

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 329
Author(s):  
Vikas N. Thakur ◽  
Sanjay Yadav ◽  
Ashok Kumar
Keyword(s):  
Primary Standard ◽  
Effective Area ◽  
National Physical Laboratory ◽  
Area Measurement ◽  
Internal Diameter ◽  
Piston Cylinder ◽  
Piston Gauge ◽  
Si Units ◽  
Physical Laboratory ◽  
Pressure Standard

The air piston gauge (APG) was established at CSIR-National Physical Laboratory, India (NPLI) since 2000. Later the same piston- cylinder(p-c) assembly was calibrated in NIST USA; however, it was never published for metrology communities. As per international protocol, the establishment of the APG as a primary standard, the effective area of p-c assembly, and masses must be directly traceable to SI units. The first time we have calculated the effective area and associated uncertainty of p-c assembly using dimension and mass metrology, traceability to the SI units, i.e., meter and kilogram. To realize the APG as primary pressure standards, we have calculated the effective area of p-c assembly of APG directly from dimension metrology, which is further supported by various other methods. The effective area values obtained in the pressure range of 6.5 – 360 kPa lie in the range of 3.356729 – 3.357248 cm² due to uncertainty limitation in the measurement of dimension of internal diameter of cylinder. The expected values of the effective area which are also measured from cross-float technique against ultrasonic interferometer manometer (UIM), primary pressure standards. The accuracy in effective area measurement is possible only when the resolution in the internal radius of the cylinder should at least be up to 5th decimal order and the uncertainty is 80 nm. The expanded uncertainty was measured nearly 11 ppm at <em>k</em> = 2 by considering the uncertainty in internal radii of cylinder and radii of piston around 80 nm.

scholarly journals Research on collaborative control of double-plunger gas prover based on EtherCAT

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2667-2687
Author(s):  
Zhipeng Xu ◽  
Feipeng Xu ◽  
Dailiang Xie
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Gas Flow ◽  
Control Unit ◽  
External Diameter ◽  
Piston Cylinder ◽  
Collaborative Control ◽  
Critical Nozzles ◽  
Parallel Mode ◽  
Working Principle

Piston prover has been widely used as a gas flow standard for its advantages of high accuracy in standard volume, flow stability and repeatability. It has also been employed as the primary gas flow standard in many countries to calibrate meters. However, it is difficult to ensure the uniformity of the inside dimension of the piston, thus the application of conventional piston provers are limited by the maximum calibration flow generated by the piston cylinder volume. In this paper, an improved piston gas prover that mainly consists of two uniform plungers was proposed. Their external diameter constitutes the flow standard. The plungers are driven by servo motor, and the high speed fieldbus EtherCAT has been introduced as the control unit. Hence the two pistons could work collaboratively and operate in three modes: single-piston mode, double-pistons parallel mode, and double-pistons reciprocating mode. Besides generating steady-flow rate, the double-plunger prover can even produce an unsteady-flow rate which could be used to research the dynamic characteristics of flow meters. The structure and working principle of the three modes were carefully introduced. Then experiments for calibrating critical nozzles were carried out, and the results show that the repeatability of the discharge coefficient could be better than 0.06%, and the pressure fluctuation during the process was less than 50 Pa.

Modern tools for accurate gas flow measurements

1970 ◽  
Vol 13 (9) ◽  
pp. 1311-1315
Author(s):  
N. M. Khusainov ◽  
A. A. Tupichenkov
Keyword(s):  
Gas Flow ◽  
Flow Measurements

Evaluation of Uncertainty in the Effective Area and Distortion Coefficients of Air Piston Gauge Using Monte Carlo Method

MAPAN ◽  
2019 ◽  
Vol 34 (3) ◽  
pp. 371-377 ◽  
Author(s):  
Vikas N. Thakur ◽  
Sanjay Yadav ◽  
Ashok Kumar
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Effective Area ◽  
Piston Gauge

Einfluß der Strömungsform des Gases auf die chemischen Transportprozesse in Halogenglühlampen

1974 ◽  
Vol 29 (10) ◽  
pp. 1471-1477
Author(s):  
Gerhard M. Neumann
Keyword(s):  
High Pressure ◽  
Laminar Flow ◽  
Gas Phase ◽  
Flow Separation ◽  
Gas Flow ◽  
Chemical Transport ◽  
Transport Processes ◽  
Inert Gas ◽  
Good Accord ◽  
Incandescent Lamps

Abstract By raising the inert gas pressure and thus changing the type of gas flow chemical transport processes in tubular halogen incandescent lamps may be influenced. At medium pressures in the region of laminar flow separation of halogen and inert gas due to thermodiffusion occurs, the halogen cycle breaks down, and bulb blackening of the lamp is observed. At low and high pressure, where the streaming behaviour of the gas phase is dominated by diffusion or turbulence, separation of halogen and inert gas is overcome and the lamps stay clean. Observed pressures for changing from laminar to turbulent flow are 3.5 atm in xenon, 5.5 atm in krypton, and > 8 atm in argon in good accord with the well-known Reynolds' criterion.

Steady State Characteristics of a Flapper-Nozzle Relief Valve

1987 ◽  
Vol 201 (2) ◽  
pp. 135-144 ◽  
Author(s):  
J S Yun ◽  
H S Cho
Keyword(s):  
Steady State ◽  
Pressure Control ◽  
Effective Area ◽  
Body Motion ◽  
Model Parameters ◽  
Dynamics Model ◽  
Relief Valve ◽  
Load Pressure ◽  
Hydraulic Load ◽  
The Relationship

The static and dynamic characteristics of flapper-nozzle type electromagnetic relief valves have not so far been investigated analytically in depth, although they have been widely used for hydraulic load pressure control. In this paper a non-linear model of the relief valve is formulated explicitly, based upon rigid-body motion and fluid dynamics. Model parameters such as discharge coefficients, effective area of the nozzle and the electromagnetic constant were identified from the steady state characteristics and physical dimensions of the valve. Based upon this constructed model the static characteristics such as the pressure override and the relationship between input current and main pressure were obtained analytically and compared with those obtained experimentally. The comparison shows that this constructed analytical model can precisely predict such characteristics.

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