Liquid Density from DP Calculator
A DP transmitter across two submerged tappings measures liquid density. Calculate density and SG from the DP and the vertical tap spacing, including remote seal fill fluid.
- SG = DP ÷ (ρw g H) + SGfill = 2,000 ÷ (9806.65 × 2) + 0.93 = 1.0320
Density from Differential Pressure
With remote seals the LP capillary rises to the upper tap and its fill fluid head is subtracted from the DP, so it is added back here.
Worked example
Taps 2 m apart with silicone filled seals (SG 0.93) read 20 mbar: SG = 2000 ÷ (9806.65 × 2) + 0.93 = 1.032.
Frequently Asked Questions
Can a DP transmitter measure density?
Yes, if both taps stay submerged, because the DP across a fixed height of liquid depends only on its density.
Why add the fill fluid SG?
The capillary on the upper seal holds a column of fill fluid that pushes on the LP side, reducing the DP by SGfill × g × H.
How accurate is DP density measurement?
Typically ±0.005 to ±0.01 SG; temperature effects on the fill fluid are often the largest error.
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