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Working principle and structure of differential pressure transmitter

Author:    Source:    Date: 2021-05-26 15:12:43
As long as it is a differential pressure flowmeter (mainly V-cone flowmeter, Velbar flowmeter) and differential pressure transmitter, they are interdependent and indispensable. Because the pressure difference in the pipeline can only be checked by a pressure difference transmitter, people describe them as a superior-subordinate relationship.
1. Working principle

The differential pressure transmitter is one of the most commonly used weight transmitters in industrial practice to prevent the medium in the pipeline from directly entering the transmitter. The pressure-sensitive diaphragm is connected to the transmitter through a capillary filled with fluid. It is used to measure the level, flow and pressure of liquid, gas or steam, and then convert it into a 4-20mA DC signal output. It is a typical self-balancing instrument, as shown in Figure 1. It is widely used in various industrial automatic control environments, involving water conservancy and hydropower, railway transportation, intelligent buildings, automatic production control, aerospace, military, petrochemical, oil well, electric power, ships, machine tools, pipelines and many other industries.

2. Principle structure

The pressure of the measured medium directly acts on the diaphragm (stainless steel or ceramic) of the transmitter, causing the diaphragm to produce a micro-displacement proportional to the pressure of the medium, changing the resistance value of the sensor, and detecting this change through the electronic circuit , Convert and output the standard measurement signal corresponding to this pressure, as shown in Figure 2.

Three, principle related parameters

Temperature range: The working temperature range of the amplifier is -29 ~ 93 (LT type is -25 ~ 70).

Measuring element filled with silicone oil: -40 ~ 104

When the flange transmitter is filled with high temperature silicone oil: -20 ~ 315, ordinary silicone oil: -40 ~ 149

Static pressure: 4, 10, 25, 3232 MPa

Humidity: Relative humidity is 5 ~ 95%

Volume absorption: 0.16cm3

Damping (step response): When filled with silicone oil, it is generally continuously adjustable from 0.2s to 1.67s.

Accuracy: 0.2%

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