I have a question regarding double-flange differential pressure level gauges
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We have a horizontal storage tank equipped with a differential pressure level gauge with double flanges, and the management requires monitoring the volume of material used on a daily basis. Since the center distance between the flanges in the high-pressure area is 200 mm from the bottom of the tank, and the flange opening has a diameter of DN50, it is definitely impossible to measure the liquid level below the flanges on the high-pressure side. But where exactly is the starting point at 0 o’clock on the high-pressure side flange? I think measurement can only begin at the center position. But the experienced workers say that 0 point is at the bottom of the flange, while others say it should be at the top of the flange. I can’t test it either. I’d like to ask the experts for advice. . . Is dual-flange differential pressure level measurement accurate for determining level? How large is the error? Our medium is very stable. EJA transmitters
As long as the fluid in your tank does not crystallize, contains no sediment, and has a stable density, using the differential pressure method for level measurement yields very high accuracy with reliable results; the accuracy is essentially that of an EJA differential pressure transmitter, namely 0.2%, with the zero point located at the center of the flange.
1. If the level of material in the tank often drops below zero, it is recommended to take the bottom of the flange as the zero point； 2. If the level of material inside the tank is usually above the zero level, it is recommended to set the zero point normally or follow the specifications provided by the instrument ； 3. As for whether it is accurate or not, it needs to be compared with the local level gauge on site; if there is a discrepancy with the local indication, recalibration is required.
Since each installation cannot achieve repeatability in the spatial position of the diaphragm at the micron level – for example, every time the flange is loosened and then re-secured, the zero point of the differential pressure gauge will shift to some extent! Therefore, when the liquid level rises to the level of the diaphragm, the zero point of the level gauge begins to increase. To be sure about this, actual measurements are necessary! Any point between the center of the diaphragm and its lower edge can potentially be the zero point. However, in most cases, the zero point lies near the lower edge of the diaphragm, that is, at a position below 1/2 of the diaphragm’s radius. If the zero point were at the center of the diaphragm, then that would simply be the delusions and nonsense of those who have never conducted experiments. But in most industrial measurement applications, the quality is quite poor, and there is little emphasis on experimental verification; as a result, such nonsense ends up becoming the prevailing view. Separator---------------------- If you think the older brother’s explanation is logical, vivid, and interesting, give him a like! :lol
I think it’s better to do some calibration; either the lower edge of the flange or the center will work, it depends on how you decide to carry out the calibration
It’s just 2.5 centimeters short; it will always be that short
Huh, huh, huh – it’s impossible to figure out where the true zero point of the instrument is; what’s the point of doing any calibration at all? What you call “calibration” is nothing but artificially creating a zero-offset error; it’s like calling a deer a horse, it’s like trying to deceive others by covering one’s ears while stealing, it’s just complete nonsense. Shiny, shiny… it makes my sexy pig-like mouth smell like excrement. Grooving.
This reference point is the center of the flange, as it cannot be measured below; however, the reference point should start at 250 mm (or 200), as the true zero point is counted from the bottom of the container； Of course, it’s also fine to define the center of the flange as point 0. In any case, the field range must match that of the transmitter; this is a fundamental requirement, otherwise there will be a mismatch between the field range and the DCS.
Hello, under normal circumstances, the liquid level in a liquid medium must be above one-third of the position of the pressure-sensitive diaphragm for the transmitter to be able to measure properly. Therefore, it is correct to start measuring from the center of the flange or above. Based on your description, you should choose the Yokogawa EJA118 series dual-flange transmitter; as long as the range is selected appropriately, a precision of 0.2% is entirely feasible.