2012 Jan 28 12:42 AM
I am trying to set-up a VCF for installations meters that self correct for guage pressure. However, the installations do not correct for altitude/air pressure, i.e. they are not absolute pressure corrected.
Therefore, I need a procedure that converts for air pressure but not guage/absolute pressure.
An example would be that the installations air pressure is 1.000 Bar, with the Gauge Pressure being 0.50 Bar. Therefore, the total pressure correction factor should 1/1.0135, NOT 1.5/1.0135.
Can anyone tell me what the VCF set-up should be?
Note I realise there's also temperature and super compressiblity involved in the VCF, however this is immaterial for my question.
2012 Jan 30 7:28 AM
Hi Jayshree,
I actually do not know the combination you have asked for but
I do find that there are a lot of options in VCF in the block for
'Measured Pressure' and 'Atmospheric Pressure' which should work for your scenario.
Most of the times the Meter is capable of self adjusting these parameters so we tend
to use Fixed VCF(in my case ).
but anyways try setting breakpoint in fm 'isu_consumption_determine'.
we have a subroutine there 'thgas_zw',look into that,probably you will get an idea on what combination to use.
Do please write back if it works out or if you get a solution. Good Luck
Cheers,
Rakesh..
2012 Feb 01 11:57 PM
We have a solution.
For the Volume Correction Factor Procedure to be used for gauge corrected meters, we've ticked Air Pressure Correction.
And then for the gauge corrected meters, we've populated the Air Pressure Correction value as being the negative value of the gauge pressure.
So, therefore for the relevant installation at say 0.6 Bar gauge pressure at an air pressure area that is 1 Bar, the pressure calcuation becomes
= (Air Pressure + Gauge Pressure + Air Pressure Correction)/(Standard Air Pressure)
= (1 + 0.6 + -0.6)/1.01325
= (1)/1.01325
= 0.9878
The number of gauge corrected meters we have is very small (<100), therefore using the Air Pressure Correction as a way of stoppping gauge pressure being double applied (once by the meter, and then by SAP) is a suitable solution.