Elgas DATCOM, Operating Instructions Manual

Page: 137 / 228

7
Technical Description of the Device
135
where:
V
c
... Corrected volume at the measurement conditions (volume
corrected based on the correction profile of the gas meter)
V
m
... Volume at the measurement conditions (primary volume)
Q ... Flow rate at the measurement conditions (primary flow rate)
The linear interpolation method is used as the implicit interpolation method to determine the
values between the calibration points.
The principal scheme of volume calculations is shown in Fig. 65.
Conditions for using Volume Correction
The conditions are in accordance with the requirements of CSN EN 12405-1 + A2:
 The correction is used if only the gas meter measures at least 10 pulses per second at
Qmin.
 Below Qmin, the correction is not applied, and the value of the correction factor specified
for Qmax is used above Qmax.
It follows from these conditions that the correction can only be applied to gas meters with a HF
pulse sensor and in the connection with ELCOR plus type.
7.9.4 Conversion of Volume to Energy
The device allows to recalculate the amount of consumed gas in the amount of energy E and it is
therefore possible to use the device as an Energy conversion device according to EN 12405-2.
The conversion of the volume to energy uses the value of combustion heat H
s
. Only when the
AGA8-DETAIL method is used, the gross calorific value Hs is calculated according to EN ISO
6976:2016 by the device. In the case of other methodologies, the fixed value of the gross calorific
value Hs is used (the user can change this value). It is thus possible to define reference
conditions (t1 / tb, pb) for the heat of combustion Hs in the device. The calculation is made by
adding increments of volumes dV
b
(and dV
bs
)) multiplied by the actual value of combustion heat
H
s
:
dE=H
s
x dV
b
, dE
s
=H
s
x dV
bs
For measuring in energy units, the device contains two additional counters, the energy counter E
and the energy substitute values counter Es.
When configuring, the energy measurement unit can be selected from the following list: MJ, kWh,
Btu.
The gas meter correction data file is uploaded to the device using the utility
program [42], [43].
Gas meter correction values are stored in a file as a table. The table can contain up
to 10 flow-dependent correction values.
Information on entering the correction profile of the gas meter in the device is
stored in the settings archive.