Final Report on Key Comparison CCM.P-K7 in the range 10 MPa to 100 MPa of hydraulic gauge pressure

Abstract

This report describes a CCM key comparison of hydraulic pressure standards of nine National Metrology Institutes that was carried out in the period from November 2002 to June 2004 in order to determine their degrees of equivalence in the range 10 MPa to 100 MPa of the gauge pressure. The pilot laboratory was PTB. The primary pressure standards were pressure balances of different design equipped with piston-cylinder assemblies operated in freedeformation, controlled-clearance or re-entrant operation mode. The transfer standard was a pressure balance equipped with a piston-cylinder assembly and a mass set. The pressuredependent effective areas of the transfer standard at specified pressures were reported by the participants and led to the reference values calculated as medians. All participants' results agree with the reference values and with each other within the expanded uncertainties calculated with a coverage factor 2, most of them even within their standard uncertainties. In addition, the results were analysed in terms of the zero pressure effective area and the pressure distortion coefficient. Also for them agreement within expanded uncertainties (k=2) is observed. The results of the comparison demonstrate equivalence of the laboratory standards and support their measurement capability statements.

Improvement of reliability in pressure measurements and international mutual recognition

“…The international equivalence of the AIST national standard was confirmed according to the results of the international comparisons of several pressure ranges [19]- [23] [25] . AIST is planning to participate actively in the future international comparisons, and will continue to ensure the international equivalence of the Japanese national standards.…”

“…We were able to obtain sufficient comparative precision that could be used in the international comparison, by understanding the details of the property of the digital pressure gauge as the transfer device and conducting appropriate corrections. Figure 8 shows the results of the calibration values at 100 MPa of the participating institutes in the two international comparisons (CCM.P-K7 [25] and APMP.M.P-K7 [19] ), including the aforementioned international comparisons. The horizontal axis shows the acronyms of the participating institutes and the country names, and the vertical axis shows the relative deviation from the international comparison reference value of the calibration values of each institute.…”

Standardisation of pressure measurement using pressure balance as transfer standard

“…The NPL100MPN has also participated in several key comparison exercises, APMP.M.P. K7 [21], CCM P. K7 [22] and APMP-SIM.M.P. K7 [23].…”

A Computer Controlled Precision High Pressure Measuring System

“…The high precision pressure calibrator thus developed consists of a hydraulic screw pump of volume 5 cm 3 , an oil reservoir of capacity 150 cm 3 , two needle valves, a DPQT pressure sensor, power supply, and an output port for gauge under calibration. All the components are mounted on a rigid stainless steel base plate of 2.5 mm thickness.…”

“…Therefore, the use of pressure transducer (PT) with intelligent instrumentation as TS is the convenient way to address such difficulties. The use of PGM as TS is limited up to 500 MPa [3][4][5][6] due to their bulky size, high costs, high operation demands and difficulties in transportation.…”