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National ESZ force standard 200 kN

Name of Standard: National ESZ force standard 200 kN

Code designation: ECM 150-2/02-020

Year of publication: 2002

Department: nr. 8011 CMI LPM Praha

Guarantor: Ing. Lukáš Vavrečka Ph.D.

Number of CMC lines provided: 1
Mode:Scope:
Uncertainty
(k = 2):
tensile loading
0,5 kN – 200 kN2·10-4
loading compressive
0,5 kN – 200 kN2·10-4
The state standard ESZ 200 kN is designed for calibration of standard force gauges with nominal forces from 20 kN to 200 kN under tensile and compressive loading.
 
The standard was custom-made for the Office for Standardization and Measurement (ÚNM) by WPM in Leipzig. It was installed in the force laboratory in the building of the then Regional Department of the Ministry of Industry and Trade in Prague 1, Celnice 5. It was put into operation in 1958.  It served as a force standard in the ÚNM until the establishment of the CSMI. After the establishment of the CSMI in 1968, it was taken over with the entire laboratory as a force standard for calibration of force standards in the range of nominal forces from 3 kN to 150 kN. Here the standard was used until 1979. In 1979 the standard was dismantled and moved to the new force laboratory in the building of the CSSMU in Prague 5, V Botanice 4. The reason for the dismantling was the destruction of the laboratory building due to the reconstruction of the area around the Square of the Republic.  After the reconstruction, the standard was installed in this laboratory. The standard was put back into operation in 1985. In 2002, it was declared the state standard of strength. The standard was operated until the 2002 flood. During the flood, the laboratory was flooded with sewer water and the standard had to be completely dismantled. In doing so, some parts were repaired and the standard was completely reconstructed. Its range of force gauge standards after reconstruction is from 20 kN to 200 kN nominal force. The standard was installed and put into operation in 2005 after the creation of new laboratories in the building in Prague 5. The first major reconstruction of the standard took place between 1979 and 1985.  The second major reconstruction took place between 2002 and 2005. Theoretical and experimental work between 1979 and 2001 was carried out by a team led by Ing. M. Chlumský managed to prepare the etalon scientifically and technically for its announcement as a state etalon, which was successfully carried out in 2002.
 
The calibration force of the etalon is generated by the action of the earth's gravitational field on the load bodies of the etalon and amplified by a lever gear with a ratio of 1:50. The standard has three load cell systems. The small load cell system contains 5 load cells for generating a force of 10 N, the medium load cell system contains one load cell for generating a force of 50 N and the large load cell system contains 39 load cells for generating a force of 100 N. Thus the standard is capable of generating a force of 200 kN in the working area.
 
The force generated by the standard is given by the equation:

Where stands for:

F

...........….

the power generated by the standard,

m

...........….

the weight of the load bodies,

g

...........….

the gravitational acceleration at the location of the load bodies,

ρvzd

...........….

air density at the location of the load bodies,

ρZT

...........….

density of load bodies.
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