Method for measuring the liquid stratification interface using a differential pressure transmitter!!
Thread Content
The principle of using a differential pressure transmitter to measure the interface between liquid layers. Could any member of the community provide more detailed information on this, including details regarding the selection of the measurement range? The density of the liquid in the upper layer is 0.8, while the lower layer consists of water. The height difference between the two layers is 1 meter. Thank you. This post was last edited by naska on 2008-2-20 at 11:12
A float-type leaf meter is the best choice for measuring the interface. If a differential pressure type is used, the measurement range is from (height x light component density) to (height x heavy component density).
Could you explain it in detail? For example, with some examples. Thank you!
Differential pressure transmitters can measure density, but I’ve never heard of them being used to measure interfaces.
The method on the second floor can only be used for measurement when the liquid level height is kept at a constant value and only the interface changes; it cannot be applied when the overall liquid level is changing. However, using differential pressure to measure liquid level is acceptable; I’ve really never heard of it being used to determine interfaces
A differential pressure transmitter can be used to measure the page. As you said: the density of the liquid in the upper layer is 0.8, while the lower layer contains water. The height is 1 meter. The tank is currently filled with this low-density liquid, which should be considered as the 0 level for the liquid surface; the pressure difference at this point can then be calculated. Then fill it with water and calculate the pressure at that moment. Then, the pressure of water minus the pressure of the low-density fluid is the differential pressure value required for the transmitter.
Density is measured using differential pressure. Make sure that the pressure lead tubes of the differential pressure transmitter are filled with a low-density liquid. There must be no bubbles.
In a two-layer liquid system, the height of one of the layers must remain constant; otherwise, it is impossible to make measurements.
Can it be understood in this way: a 1-meter-high layer of low-density liquid is added to the positive pressure chamber to calibrate the zero point, and then another 1 meter of water is added to the same chamber to calibrate the range. In other words, 1 (height) * 1 (density) – 1 (height) * 0.8 (density) = the differential pressure value. Is this correct? Please advise!
I’ve learned it.* :) :) :)
The interface can be measured using a differential pressure transmitter. Let the density of the liquid with higher density be ρ, and the density of the liquid with lower density be ρ1. The height of the tank is h; then the range of the differential pressure transmitter is P = (ρ – ρ1) * g * h. The following points need to be taken into consideration: 1. The zero point of the differential pressure transmitter must be adjusted, with the adjustment amount being ρ1g*h. 2. It is advisable to use a double-flange differential pressure transmitter, as this helps to avoid fluctuations caused by changes in the negative-pressure line I used this method to measure the interface before; it wasn’t very effective. If precise measurements of the interface are required, it is recommended to use a float. This approach isn’t very reliable, as the density can change during industrial production processes. Moreover, when using a differential pressure transmitter for interface measurement, the range is usually quite small, and such minor changes can result in significant measurement errors!
The poster didn’t clarify the conditions. If the liquid level remains constant, that is, h stays the same, the above method works. Otherwise, it is not possible to measure the interface.
The total liquid level remains constant; what changes is the amount of the light and heavy phases!
When the tank is filled with a low-density medium, the measured pressure difference at this time is zero； When filled with a high-density medium, the pressure difference measured at this point represents the full scale.
When using floats, it is necessary to consider whether the medium contains dust and impurities. The differential pressure method is used, along with a diaphragm type design; especially when the difference between the two densities is not large, the measurement range becomes somewhat limited, making it difficult to select an appropriate transmitter model
Using a differential pressure edge feeder does not yield very good results
There is a problem with using float-type ones, as the float ball tends to get stuck. So personally, I think using differential pressure is better, but it’s essential to ensure that the level is full; otherwise, the measured interface level will be inaccurate
The issue is quite profound and worth studying a bit.
The measurement media are highly corrosive aqueous hydrofluoric acid solutions (below 10%, with a density of about 1.05) and liquid materials (with a density of about 1.22), at a working pressure of 1.6 MPa. It is necessary to determine the interface position between the two materials inside the hermetically sealed vertical tank (the interface is to be kept within an 800 mm range as per process requirements); please recommend a suitable level gauge. Previously, float flap level gauges, differential pressure transmitters, and radio frequency admittance level gauges were used, but none of them yielded satisfactory results. Currently, weighing is used in combination with inspections of the discharge outlets. This post was last edited by zhx7540 on 2008-4-11 15:14.]