WIKA CPB5000HP - Handbuch (Seite 9)

Pressure Balance High-Pressure GB
CPB 5000 HP
WIKA Operating Instructions Pressure Balance High-Pressure Version 2.3 9
2.3.4 How the cross-sectional surface responds to pressure .
At higher pressures, the effective cross-sectional surface changes due to the pressure load.
The ratio of the cross-section and prevailing pressure is linear within an initial approximation. It is
represented by the coefficient of expansion caused by pressure distortion (
λ).
pressure Nominal 1
pressure Nominal
⋅ +
=
λ
pressure True
Example:
Measuring point: 1000 bar
System with distortion coefficient: 10
–7 1/bar:
bar bar pressure True 90 . 999
1000 10 1 1
1000
7
=
⋅ ⋅ +
=
−
Without the correction, measurements would all be "off" by 0.01 %.