SMT3151LT liquid level (pressure/differential pressure) transmitter

Description

The liquid level (pressure/differential pressure) transmitter is a pressure signal measured at the reference side of atmospheric pressure (low pressure side), with one or two ports for flange (or other connection) and process pipe connection.

Working principle:

On the basis of common pressure/differential pressure transmitter, one or two isolation membrane boxes are added to measure the liquid receiving part.Mainly used for measuring high temperature, easy to solidify or crystallize, containing solid suspended matter, too viscous, corrosive or other needs to maintain sanitary conditions, non-polluting media. 

The basic measurement element is the same as the technical performance and technical index of the 3151 pressure/differential pressure transmitter. After adding the remote transmission device, there will be a small decrease in measurement accuracy, slow reaction speed, and the installation position should be paid attention to when the pressure is relatively small, so as to ensure that the measured pressure is within the measurement range of the basic measurement element.

3151LT Flange Specification Sheet

Common flange flush type specifications are as follows:

DN50(2 ") flange dimension specification sheet

DN80(3 ") flange dimension specification sheet

DN100 (4 ") flange dimension specification sheet

DN40 Flange size specification sheet

Common flange insertion barrel specifications are as follows:

DN50(2 ") flange size specification sheet

DN80(3 ") flange size specification sheet

DN100(4 ") flange size specification sheet

Liquid level (pressure/differential pressure) transmitter selection specifications table

Selection example： 3151LT4SFA50AAA22AM4Da    0～20kPa

Installation requirements for liquid level differential pressure transmitter

In order to accurately measure the liquid level, in addition to the correct selection and verification of the differential pressure transmitter, it must also be noted that the installation of the entire system meets the requirements. The indication value of the transmitter sometimes does not reflect the actual parameters of the measured medium, because the measurement system itself will produce errors. System installation requirements include: the opening position of the pressure tap, the proper laying of the connecting conduit, and the mounting position of the transmitter.

First of all, the pressure tap should be in a region where the fluid flow is smooth and there is no eddy current, and the process parameters should be ensured in the process. For example, when the differential pressure transmitter is used to measure the water level of the boiler drum, the actual water level of the steam drum is different in the axial and radial directions of the steam drum, generally in the axial direction, the middle water level is high, and the water level on both sides is low; The side of the lowering tube is higher on the denser side. The condenser liquid level transmitter of a power plant turbine is close to the condensate pump inlet due to the position of the measuring point. When the condensing pump is running, it causes the water surface to sink at the point of the point, which causes the transmitter to be significantly lower. The position of the measuring cylinder is moved to a distance from the inlet of the condensing pump, and the condenser water level transmitter is consistent with the actual water level indication on the spot to ensure safe and stable operation of the condenser.

Secondly, when measuring the liquid level, the differential pressure measured by the differential pressure transmitter is relatively small, generally between several kPa and 100 kPa, so the entire measurement system has a great influence on the measurement accuracy. As shown in Figure 1, when installing the pressure guiding tube, the horizontal section of the pressure guiding tube should have a certain inclination, and the inclination should be as large as possible to avoid accumulation of liquid inside the pressure guiding tube, resulting in inaccurate measurement. When the transmitter range is small, the transmitter output will fluctuate. In addition, when the transmitter is put into operation, the air bubbles in the liquid column of the pressure guiding tube should be drained as much as possible. These accumulated gases will affect the accuracy of the measurement. It is also conceivable to arrange the exhaust device at the highest point of the upper bend of the pressure guiding tube.