scholarly journals Characterization of spinning rotor gauge-3 using orific flow system and static expansion system

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 325
Author(s):  
Ashok Kumar ◽  
Vikas N. Thakur ◽  
Harish Kumar
Keyword(s):  
Flow System ◽  
National Physical Laboratory ◽  
Transfer Standard ◽  
Physical Laboratory ◽  
Accommodation Coefficients ◽  
Orifice Flow ◽  
Expansion System

This article elucidates the calibration of newly procured spinning rotor gauge (SRG 3) from MKS Instruments, USA using primary vacuum standards: Orifice flow system (OFS) and Static expansion system (SES) established at National Physical Laboratory, India (NPLI) in the range of 10<sup>-4</sup> Pa to 1 Pa and further compared with manufacturer reported value which was calibrated by transfer standard of National Institute of Standards &amp; Technology (NIST). The key parameters to calculate the pressure measured by SRG is the accommodation coefficients. The accommodation coefficients for N<sub>2</sub> gas obtained using OFS, SES, and calibration report form NIST USA (SRG2) are 0.957, 0.961, and 0.954 respectively.

Characterization of Capacitance Standards at High Frequency at National Physical Laboratory, India

MAPAN ◽  
2017 ◽  
Vol 33 (2) ◽  
pp. 131-137
Author(s):  
Satish ◽  
Jyoti Swami ◽  
Babita ◽  
Thomas John
Keyword(s):  
High Frequency ◽  
National Physical Laboratory ◽  
Physical Laboratory

scholarly journals 75th Foundation Day of CSIR-National Physical Laboratory: Celebration of Achievements in Metrology for National Growth

MAPAN ◽  
2021 ◽  
Author(s):  
Sanjay Yadav ◽  
Goutam Mandal ◽  
V. K. Jaiswal ◽  
D. D. Shivagan ◽  
D. K. Aswal
Keyword(s):  
National Physical Laboratory ◽  
Physical Laboratory ◽  
National Growth

Comparison of the acceleration due to gravity at the National Physical Laboratory, Teddington, the Bureau International des Poids et Mesures, Sèvres, the Physikalisch-Technische Bundesanstalt, Brunswick, and the Geodetic Institute, Potsdam

1952 ◽  
Vol 213 (1114) ◽  
pp. 408-424 ◽  
Keyword(s):  
National Physical Laboratory ◽  
Absolute Value ◽  
Geodetic Institute ◽  
Physical Laboratory ◽  
The Absolute

The values of gravity at these stations have been compared by means of pendulum observations with Invar invariable pendulums. The observed differences of gravity from the National Physical Laboratory are: B. I. P. M. -256·73 ± 0·49 mgal P. T. B. + 68·68 ± 0·49 mgal Bad Harzburg - 15·68 ± 0·49 mgal The accuracy of the measurements is not so great as has been achieved once or twice previously with the same apparatus, mainly because the changes in the lengths of the pendulums were greater than usual. These differences have been combined with German pendulum observations and with gravimeter comparisons with the following results: Value of gravity at N. P. L. on the Potsdam system: 981196·29 ± 0·3 mgal. Differences between sites of absolute determinations of gravity: N. P. L. - B. I. P. M. +256·45 ± 0·3 mgal N. P. L. - P. T. B. - 68·98 ± 0·3 mgal P. T. B. - Potsdam - 8·95 ± 0·4 mgal ( g at Potsdam = 981274 mgal.) The effects of these results on gravity surveys based on Cambridge and on the absolute value of gravity are indicated.

scholarly journals A standard measuring machine

1912 ◽  
Vol 87 (597) ◽  
pp. 385-390
Keyword(s):  
National Physical Laboratory ◽  
Standard Measuring ◽  
Physical Laboratory ◽  
Accurate Comparison ◽  
Measuring Machine ◽  
Regular Work ◽  
Absolute Measurements ◽  
Line Standard

In some physical researches it is required to measure the dimensions of a regular solid, whether parallel-sided, cylindrical, or spherical-ended, with the greatest possible accuracy. Again, in the regular work of a metrology bureau, accurate comparison of the size of an end-standard of length with reference to a line-standard is required. Until 1906 the only apparatus available for these purposes was the measuring machine made for comparing engineering gauges. In that year the writer described a machine based on the principle of electric touch, which was much more delicate than the older mechanical machines. It also had facilities for exploring the solid under test, to prove its accuracy of figure. This machine has been installed and used in the National Physical Laboratory since 1909. Improvements in it were described later. The present paper gives an outline of an improved machine of the same type embodying the experience gained in using the 1906 machine. The chief novelties are: (1) greater strength in the supporting parts, and consequent rigidity of the whole apparatus; (2) larger and much improved table to carry the solid under test; (3) improved measuring-ends; (4) an innovation for making absolute measurements, whereby the line-standard moves but the reading microscope remains fixed; (5) side girders to relieve the bed of load and so reduce friction, abrasion, and strain.

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