How to calculate the level measurement for a double-flange transmitter? Thank you
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There is currently a Yokogawa EJA double-flange transmitter in use to measure the level of two liquids with densities of 567 kg/m3 and 956 kg/m3, respectively. For a height of 1400 mm, how should the upper and lower limits for measurement be set? Thank you!
This post was last edited by ylb913 on 2016-8-23 06:54. The double-flange transmitter is used to measure the level of two liquids with densities of ρ_light = 567 kg/m3 and ρ_heavy = 956 kg/m3, at a height of 1400 mm. 1. The lower limit (0 points) corresponds to the entire measurement range being filled with a low-density medium; this value is 1400*0.567=793.8 millimeters of water column, and when multiplied by 9.8, it equals 7779 Pa. ——In practice, the formula ρgH is commonly used; the unit for density ρ is in kg/m3, and the unit for height H is in meters. 567*9.8*1.4=7779 Pa, and the result is the same. The upper limit (100%) corresponds to the entire measurement range being filled with a high-density medium; the value is 956*9.8*1.4=13116 Pa. 2. Then, both the double-flange level measurement (level boundary) methods involve a negative drift. (1) For the measurement of liquid level, the negative migration amount is ρ_fill gH, where “ρ_fill” is the density of the fluid filled inside the double flanges (such as silicone oil), and H is 1.4 meters corresponding to the full scale; thus, the unit of ρ_fill gH is also Pa. (2) For the measurement of the boundary level, its negative migration amount is (ρ_full – ρ_light)gH.
Thank you so much, I’ve learned it! ! ! ! ! ! ! ! !
I have a question: I work in the process area. When setting up the table, is it necessary for both the positive and negative pressure sides to be submerged in the material? Can the settings be adjusted when the tank is empty? Our installation also has a dual-method interface meter, but the technician hasn’t managed to get it working properly; they insist on filling the tank with materials of different densities before making adjustments. Is there any basis for that? ? ?
No need; it can be adjusted even when it’s empty. There will just be a slight error after adjustment. Once all the light and heavy media have been filled in, adjust it again and that’s it
The error between the theoretical value and the actual value; of course, if the requirements are not strict, this error can be ignored
You need to fill the tank with liquid in order to use double flanges; if you use the water level method, you can determine the height of the water
There are software programs that can do the calculations directly; it’s exhausting to do them by hand.