In this article, we will we discussing Calibration of the DP transmitter when the transmitter installed above 0% level.
(1) DRY LEG
Let, consider the above-stated example in which we have a height from the centre to centre tapping is 5470 mm and the height from 0% to HP connection is 1250 mm.
1. Calculate Range :
Range = centre to centre (0% to 100%) * S.G.
= 5470 * 1.12
Range = 6126.4 mmH20
2. Calculate LRV :
LRV = HP - LP
= (1.12 * (-1250)) - 0
(Here transmitter installed in elevation so we have minus the height and in suppression, we have to add that height.)
LRV = -1400 mmH20
3. Calculate URV :
URV = LRV + Range
= 6126.4 - 1400
URV = 4726.4 mmH2o
(2) WET LEG
Now let consider same example as above with this time for wet leg having a specific gravity of 1.17
1. Calculate Range :
Range = centre to centre (0% to 100%) * S.G.
= 5470 * 1.12
Range = 6126.4 mmH2o
2. Calculate LRV :
LRV = HP - LP
= (-1250 * 1.12) - (4490 * 1.17)
(Due to wet leg and elevation height is 5470 + 270 - 1250 = 4490)
= - 1400 - 5253.3
LRV = -6653.3 mmH2o
3. Calculate URV :
URV = LRV + Range
= -6653.3 + 6126.4
URV = -526.9 mmH2o
After calculation of LRV and URV put this value in the transmitter.
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