How to install differential pressure level transmitters more reasonably

It’s best to send the image for a look; there are many reasons why measurement might not be possible.

What is the process medium inside the reactor? Process parameters?

The medium in the tank is crude oil, with a height of 3.8 m. The transmitter’s range is set at 0–28 kPa. What is most confusing is that when the tank is filled with crude oil, the liquid level is indicated as being at half capacity. ,

Use HART or FLUKE to do some debugging to see if it’s a problem with the range setting inside the instrument.

Check whether the internal parameters of the transmitter are set correctly; this is where the problem usually lies.

For measuring the liquid level in a sealed container, it is necessary to perform negative migration on the gauge; a range of 0~28 KPA is incorrect – negative migration should be applied instead.

In the reaction vessel, does the medium remain unchanged before and after the reaction? If there are changes, the density will be different. Differential pressure level gauges calculate levels based on density; different densities result in different measurement values.

:) :) Schematic diagrams for the installation of pressure and differential pressure transmitters: 1. Installation diagram for pressure transmitters; 2. Installation diagram for differential pressure transmitters; 3. Instructions for installing pressure and differential pressure transmitters.  A straight pipe section should be ensured at the pressure sampling point, with a length of more than 5D (the diameter of the pipeline) on each side；  When taking pressure readings from a steam pipeline, a pressure tap should be installed on the side of the pipeline ；  The balance tank should be installed at the highest point of the pressure guiding pipe ；  The drain pipe should be installed near the connection point of the transmitter pressure tap ；  The distance between the pressure tapping point and the transmitter’s pipeline should be greater than 1 meter ；  The installation location of the transmitter should be below the pressure sampling point. This post was last edited by zlky2005 on 2009-2-6 08:59.]

Since it is a differential pressure level gauge, should the low pressure value be taken from the space above the tank or from the atmosphere?

It relates to installation and parameters, as well as model selection.

Based on what the original poster said, I think you should consider the following aspects: 1. Recalculate the transmitter’s range based on the density of crude oil, and calibrate the transmitter. 2. According to the conditions mentioned by the poster, the transmitter does not require negative migration; one end is connected to the atmosphere. A pressure-type transmitter can be used to directly measure the pressure generated by the crude oil, which can then be converted into a liquid level height. You can check according to the installation manual to see if the installation meets the requirements.

If the differential pressure level transmitter is of the double-flange type, both flanges should be connected to the reaction vessel, and negative migration should be applied in order to eliminate the static pressure generated by the upper flange

In my opinion, if the installation is correct, on the one hand, considerations can be given to the settings of the transmitter; on the other hand, it is necessary to check whether the tank operates under negative pressure. If that is the case, it can also cause distortion in the liquid level readings.

First, the range of the differential pressure transmitter must be calculated based on the density of the crude oil and the measured height. Additionally, since the transmitter is installed at the bottom of the container, it is necessary to determine the distance from the transmitter to the bottom of the container; the pressure corresponding to this distance needs to be compensated for by the positive offset of the transmitter. Second, the negative pressure chamber of the transmitter is connected to the atmosphere. For this connection to be effective, it is necessary that the container in question be an open-container, meaning that the pressure at the top of the container must be equal to the atmospheric pressure; otherwise, the negative pressure side must be connected to the top of the container

We all know that if the medium is water, 1 meter equals 10 KPa. If the liquid level in your tank is 3.8 meters, then the pressure corresponding to that is 38 KPa. Check the density of crude oil; multiplying it by 38 gives you the range of the transmitter you need. After determining the range, select the appropriate model: for closed tanks with static pressure, use a double-flange design; for open tanks, the liquid level can be measured directly using pressure

The cause should be sought in the density of the crude oil, as well as the range and zero setting of the instruments.

Since the crude oil level is measured using a differential pressure transmitter and the crude oil is viscous, an isolation fluid should be filled in the positive pressure pipe, and positive migration should be carried out when it is not in use. If isolation fluid is filled under both positive and negative pressures, negative migration occurs. Also, you mentioned installing it at the bottom of the reactor – but how many bottoms are there? It’s also possible for dirty substances to block the negative pressure pipe. Last edited by Behind the moon on 2009-2-14 21:26.]