In this article, we will we discussing Calibration of the DP transmitter when the transmitter installed below 0% level.
(1) DRY LEG
Let, consider the above-stated example in which we have a height from the centre to centre tapping is 8360 mm and the height from 0% to HP connection is 310mm.
1. Calculate Range
Range = centre to centre (0% to 100%) * S.G.
= 8360 * 1.21
Range = 10115.6 mmH20
2. Calculate LRV
LRV = HP -LP
= (1.21 * 310) - 0
LRV = 375.1 mmH20
3. Calculate URV
URV = LRV + Range
= 375.1 + 10115.6
URV = 10490.7 mmH2o
(2) WET LEG
Now let take same above example with this time for wet leg having a specific gravity of 1.25
1. Calculate Range
Range = centre to centre (0% to 100%) * S.G.
= 8360 * 1.21
Range = 10115.6 mmH2o
2. Calculate LRV
LRV = HP - LP
= (310 * 1.21) - (8880 * 1.25)
(Due to wet leg add height 310+8360+210 = 8880)
= 375.1 - 11100
LRV = -10724.9 mmH2o
3. Calculate URV
URV = LRV + Range
= -10724.9 + 10115.6
URV = -609.3 mmH2o
After calculation of LRV and URV put this value in the transmitter.
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