Regarding the use of pressure transmitters to measure liquid level
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There is currently a single-flange diaphragm pressure transmitter used for measuring liquid level. The transmitter’s range is 0–35 KPa, while the liquid level range is 1.3 m–3.2 m. What should be the corresponding pressure range?
This requires the density of the liquid, P=pgh
First, the medium density must be known in order to determine the pressure range; a single flange is only suitable for measuring the level of liquids in non-pressure vessels.
Convert it using the medium density and the liquid level height to be measured, and provide the margin
First, ensure that the specified range is correct (1.3m–3.2m). Next, determine the density of the medium under the operating conditions. Then, using the formula provided on page 2 (P = pgh), calculate the pressure values at 1.3m and 3.2m. After that, adjust the zero point of the transmitter to these calculated values, and then compute the pressure value at 3.2m. Finally, apply pressure to check the zero point and range values. It can be determined from the density of water under standard conditions. The zero point is 13 KPa, and the range is 32 KPa.
Floor 7 is correct; after measuring the density of the liquid, dividing it by the density of water and then multiplying by zero and the full scale respectively yields the required zero point and full scale.
For example, the density of water is 1.35 meters; in a tank of that height, the liquid level corresponds to 35 KPA. As a general rule, 1 meter of liquid depth equals 10 KPA. When measuring water or other liquids, one simply needs to multiply this value by the density of the liquid in question
This post was last edited by 1111111 on 2019-3-19 09:39. The conversion from pressure to liquid level is as follows: △P = ρgh; h = △P ÷ (ρg). For measurements with ordinary precision, g is taken as 9.8, and thus h = 0.10204 × △P ÷ ρ. The unit of △P is kPa, the unit of ρ is grams per cubic centimeter, and the unit of h is meters
The poster said, “The liquid level range is 1.3 m – 3.2 m.” This 1.3 meters is likely measured from the bottom of the tank. If the reference point for the liquid phase in the differential pressure gauge is at this 1.3-meter mark, then the pressure at that point is 0 kPa. The area below 1.3 meters is not within the measurable range of the differential pressure gauge; it’s known as the dead zone. The area above 1.3 meters is within the measurable range. Therefore, the measurable range for the liquid level is 3.2 – 1.3 = 1.9 meters. :lol