Elgas DATCOM, Operating Instructions Manual

Page: 143 / 228

8
Metrological Features
141
instead of "calculated" to "Constant value". The range of the constant entered is not limited.
Fig. 68 Setting the constant compressibility value for calculating C (SW Compass)
8.4 Volumes Measurement and Calculation
To measure and calculate volumes, the following counters are used for each channel in the
device:
V
m
- Volume counter under the measurement conditions (primary volume)
V
c
- Corrected volume under the measurement conditions (volume corrected
based on the correction profile of the meter)
V - Volume V
m
or V
c
Vs - Operating volume counter at error conditions (substitute primary
volume)
Vb - Volume counter at base conditions
Vbs - Base volume counter at error conditions
8.4.1 Calculation of conversion number C for volume conversion
As stated in paragraph 7.9.1, the following relation applies to the calculation of volume under
basic conditions:
V
b
= V * C
The following applies to the conversion number:
C = p *
T
b
* 1
p
b
(t + 273.15) K
The conversion number C depends on the degree of compressibility of the gas K, the reference
conditions (pb, Tb), the gas pressure p and the gas temperature t.