The differential pressure from the double-sided pressure guiding tube directly acts on the two-sided isolation diaphragm of the transmitter sensor, and is transmitted to the measuring element through the sealing liquid in the diaphragm. The measuring element converts the measured differential pressure signal to the corresponding electrical signal and then transmits it to the converter. After amplifying and other processes, the differential pressure signal is output as a standard electrical signal.
1. Combined with the throttling element, the liquid flow is measured by the differential pressure value generated before and after the throttling element.
2. The differential pressure transmitter for level measurement uses the pressure difference produced by the liquid's own gravity to measure the height of the liquid.
3. Directly measure the pressure difference of different pipelines and tank liquids.
(1) Measuring range, required accuracy and measuring function;
(2) The environment faced by the measuring instrument, for example, industrial environment of petrochemical industry, the thermal (toxic) and explosive situations, or has high temperature;
(3)The physical and chemical properties and state of the measured medium, such as the working conditions with strong acid, strong alkali, thickness, or the conditions that are easy to solidify, crystallization, and vaporization;
(4) Changes of temperature indicator transmitter in operating conditions, such as changes in medium temperature, pressure, and concentration. Sometimes it is necessary to consider the changes in the concentration and density of the gas and liquid phases from the start to the point where the parameters reach normal production;
(5) The structure, shape and size of the container under test, the equipment accessories in the container and various inlet and outlet pipe ports must be considered, such as towers, solution tanks, reactors, boiler drums, vertical tanks, and spherical tanks;
(6) Other requirements, such as environmental protection and hygiene requirements;
(7) The selection of engineering instruments should be considered in a unified way, and it is required to reduce the specifications and varieties as much as possible, and reduce the spare parts to facilitate management;
(8) The actual process situation:
① Check the physical and chemical properties and cleanliness of the medium. The conventional differential pressure transmitter and the float type liquid level transmitter are preferred, and the material of the part that contacts the medium should be selected;
② Single flange differential pressure transmitter can be used for some suspended solids, foam and other media. Some media that are easy to precipitate and crystallize are suitable for plug-in double flanged pressure transmitters;
③ Consider the types of equipment the tested object belongs to. Taking sinks and tanks as examples, as the volume of the sink is small, the measurement range will not be too large; while the volume of the tank is larger, the measurement range may be larger;
④ As we cannot dig holes in the equipment, we can use RF level gauges to
measure the liquid level of high-viscosity medium and high-pressure equipment;
⑤ In addition to the problems about measurement methods and technical problems, there are also problems about instrument investment.