KROHNE Summit 8800 Vol 2 - Manual (Page 185)

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08/2013 - MA SUMMIT 8800 Vol2 R02 en
SUMMIT 8800 APPENDIX 2: GAS CALCULATIONS 17
With:
cal op
P P = P
− ∆
Equation 24 Delta meter body pressure
Where:
Pop Field operation pressure [Pa]
Pcal Calibration pressure [Pa]
3) For both directions the volume flow rate is corrected as follows:
max 0
1
0
1
/ .
* *
re bodypressu atur bodytemper
line t p bc
Q
Q
Q
Q
q q 











=
Equation 25 Bi-directional volume flow rate
Where:
qbc p/t meter body corrected volume flow [m3/hr]
qline uncorrected volume flow [m3/hr]
17 .2 Low flow cut-off control
The low flow cut-off entered in m³/h, determines whether the stream status is on-line or off-
line. As well as controlling the display status, this limit determines whether the stream can be
considered ‘non-flowing, along with environment conditions which may influence the setting.
For example expansion of gas due to increase of temperature may indicate a small flow. This
value is normally around the accuracy of the meter applied. The default value is around the +/-
1%.
17 .3 Perform meter curve linearisation
The gas meter linearisation correction can be entered as a table of data points of flow rate and
corresponding error. The size of the table can be selected from 2 to 20 points. The correction
type is linear where the correction is applied through the operating range.
CallErr
q q
actual
t p b c bc +
=
% 100
% 100
*
/ .
Equation 26 Corrected volume flow rate
Where:
qbc Corrected volume flow [m3/hr]
qbc.p/t Corrected volume flow for pressure and temperature [m3/hr]
CallErractual Meter error at actual flow rate [%]
17 .4 Calculation for normal volume flow rate
The flow computer will calculate the flow rates for corrected volume qN, mass qM and energy
qE according to the following equation: