# Calculate Differential Pressure Sensed by Level Transmitter

#### Question :

Calculate the differential pressure sensed by the level transmitter at three different water levels in this boiler steam-drum level measurement system: The measurable points are 0%, 50%, and 100% of transmitter range. Assume a density for (hot) boiler drum water of 36 lb/ft3 , a density for steam in the drum of 7 lb/ft3 , and a density for (warm) water in the “wet leg” of 61.8 lb/ft3 . If the pressure at the “low” (L) side of the transmitter is greater than the pressure at the “high” (H) side, be sure to express the differential pressure quantity as a negative number.

Credit will be given for correctly calculating each of the differential pressures:

• (6 points) Transmitter ∆P at 0% water level     = _______”W.C.
• (6 points) Transmitter ∆P at 50% water level   = _______”W.C.
• (6 points) Transmitter ∆P at 100% water level = _______”W.C.

1. (6 points) Transmitter ∆P at 0% water level = -38.832 ”W.C.
2. (6 points) Transmitter ∆P at 50% water level = -31.864 ”W.C.
3. (6 points) Transmitter ∆P at 100% water level = -24.896 ”W.C.

Also Read : Boiler Drum Level Measurement Principle

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### 1 thought on “Calculate Differential Pressure Sensed by Level Transmitter”

1. Instrument Range:
LV =[ [( 9″ x 36 + 40″ x 7) – 49″ x 61.8] x 0.0005787037] / 0.036127292000084 lbs/in3
= – 38.83 ” WC at standard condition
or LV = – 1.40289 psi
UV = [ [( 39″ x 36 + 10″ x 7) – 49″ x 61.8] x 0.0005787037] / 0.036127292000084 lbs/in3
=-24.896″ WC at standard condition
or UV = -0.89942129054 psi
Density water at 0.036127292000084 lbs/in3 standard conditions
Controller Range: -15″ to 15″ WC