Dual-flange differential pressure transmitter measurement interface
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The density of Medium 1 is 0.987, and the density of Medium 2 is 1.25. The flange spacing is 2.4 meters. Could anyone please tell me what the range of the transmitter will be?
Is it a jar with two different media? What’s wrong with the transmitter’s range?
4 mA corresponds to a pressure of 23.2 kPa, while 20 mA corresponds to a pressure of 29.4 kPa. The values above are calculated using the pressure formula; it is assumed that the entire 2.4 m length between the two flanges is filled with liquid.
Thank you. Does that mean the two flanges are in full contact with the medium?
The range is 2.4*（1.25-0.987）*10KPA
First, it is necessary to ensure that the measurement point is located between the two pressure tapping flanges at different heights in order for the transmitter to function properly. Assuming the density of the isolation fluid is ρ, the maximum range value is obtained when the liquid level is at the lower pressure tapping flange: P_max = 1.25*2.4*9.8 – ρ*2.4*9.8. The minimum range value is achieved when the liquid level is at the upper pressure tapping flange: P_min = 0.987*2.4*9.8 – ρ*2.4*9.8. The transmitter’s range can be determined through these calculations.
This method is more reliable than the calculated one
It’s that the total liquid level is always higher than the flange on the level gauge
The range is easy to calculate: p = (density 2 – density 1) * gravitational acceleration * flange spacing. The zero-point shift is p1 = density 1 * flange spacing * gravitational acceleration. The physical range is from (0 – p1) to (p – p1)
The 6th floor is correct; the range is from P_min to P_max (after canceling out the shift)
First, consider the maximum measurement range: (1.25 – 0.987) * 2.4 * 10 KPa = 6.3 KPa. Next, look at the zero point. When using a diaphragm-sealed differential pressure transmitter to measure the interface level, it is required that there must be liquid in both the upper and lower flange ports. If the upper flange port (the negative pressure chamber) is filled with a liquid of lower specific gravity, then that value serves as the zero point. Therefore, the zero point is 0.987 * 2.4 * 10 KPa = 23.68 KPa. Now, taking migration into account, the transmitter must be installed below the positive pressure chamber. Assuming ordinary silicone oil is used, the migration amount is 0.93 * 2.4 * 10 = 22.32 KPa. Thus, the zero point of the interface level meter is 23.68 – 22.32 = 1.36 KPa. The measurement range is then 1.36 + 6.3 KPa = 7.66 KPa; in other words, the transmitter’s measurement range is from 1.36 to 7.66 KPa