Differential pressure transmitter is one of the most widely used instruments in industrial production. There are also many physical parameters measured by it. For example, pressure, liquid level and flow rate can be obtained through it, which is important for industrial production. significance. This article is a brief introduction to the debugging steps and requirements that need to be paid attention to during the use of differential pressure transmitters. *** The specific content can pay attention to other contents of our wang station. Differential pressure transmitters are widely used in industrial production and have important significance for industrial production. The effect of measuring industrial flow is very significant. Usually used with orifice flowmeters, V-cone flowmeters, elbow flowmeters, powerbar flowmeters, and annubar (both beam tube) flowmeters. As the detection and transformation part of the process control system, the differential pressure transmitter converts the process parameters such as differential pressure (pressure), flow rate and liquid level of liquid, gas or steam into a unified standard signal (such as DC4mA~20mA current) as a display. Input signals from meters, calculators and regulators for continuous detection and automatic control of the production process. The differential capacitive pressure transmitter consists of a measuring part and a conversion amplifying circuit. The central movable high plate and one side fixed to form two planar capacitors HC and LC. The movable high plate and the two sides are fixed to form two pressure sensing chambers, and the medium pressure acts on the central movable high plate through the filling liquid in the two chambers. Generally, an ideal liquid such as silicone oil is used as a filling liquid, and the medium to be measured is mostly a gas or a liquid. The function of the isolating diaphragm not only transmits pressure, but also avoids damage to the capacitor plate. KINMAN, a leading manufacturer in China, specializing in a galaxy of Trailers & Trailer Parts . Cam Buckle Strap, Cam Buckle Straps, Straps, Strap, Belt, Cam Strap NINGBO KINMAN AUTO PARTS CO.,LTD. , https://www.kinmantrailer.com
1. Differential pressure transmitter Wiring :
(1) Remove the electronic housing.
(2) Connect the positive *** wire to the “PWR/COMN†terminal block and the negative *** wire to the “-†terminal block. Be careful not to connect the live signal cable to the test terminal (test). The power supply will damage the test tube in the test circuit. Shielded twisted pairs should be used to obtain the *** measurement. To ensure proper communication, 24AWG or cable should be used.
(3) Seal the unused conduit interface on the transmitter housing with a conduit plug.
(4) Re-tighten the cover.
2. Installation requirements for differential pressure transmitter:
(1) Introduce the pressure tube outside the elbow sensor (positive pressure) into the positive pressure chamber of the three-valve group and the differential pressure transmitter, and introduce the inner (negative pressure side) pressure tube of the elbow sensor into the three-valve. Connect the negative pressure chamber of the differential pressure transmitter;
(2) The installation position of the differential pressure transmitter on the process pipeline is related to the measured medium. In order to obtain a higher installation effect, the following conditions should be considered:
a. Prevent the transmitter from coming into direct contact with corrosive or overheated measured media;
b. Prevent the dross from depositing and clogging in the pressure guiding tube;
c. The length of the pressure guiding pipe on both sides of the positive and negative pressure should be the same as possible;
d. The liquid column indenter in the pressure pipe on both sides of the positive and negative pressure should be balanced;
e. The pressure piping is installed where the temperature gradient and temperature fluctuations are small.
(3) When measuring the liquid flow rate, the differential pressure transmitter should be installed beside or below the pipe to be tested so that the air bubbles are discharged into the pipe;
(4) When measuring the gas flow rate, the differential pressure transmitter should be installed beside or above the pipe to be tested so that the accumulated liquid can easily flow into the pipe;
(5) When measuring the steam flow, the differential pressure transmitter should be installed under the pipe to be tested so that the condensate can be filled in the pressure pipe.
Special care should be taken to prevent the temperature of the differential pressure transmitter from contacting the medium when the steam or other high temperature medium is measured.
3. Differential pressure transmitter is used correctly:
Operation procedure when the integrated three-valve and differential pressure transmitter are put into operation: First, open the two drain valves on the differential pressure transmitter, then open the balancing valve, and then slowly open the two shut-off valves, and the pressure guiding tube will be opened. The air or dirt is removed, the two drain valves are closed, and the balance valve is closed, and the transmitter can be put into operation. Differential pressure transmitter features online verification operation procedure: first open the balance valve, close the two shut-off valves, you can verify the characteristics of the transmitter. Take the Rosemount ***3051 differential pressure transmitter as an example to introduce the adjustment of the differential pressure transmitter. Loosen the explosion-proof *** screw on the electronic housing, rotate the explosion-proof ***, and expose the characteristic adjustment button. (Note that there are two buttons, one for the feature adjustment button (zero) and the other for the default button (SPAN). Pay attention to the feature adjustment button. Pressurize the transmitter and the pressure value is equal to the pressure value of the 4mA output. Press the characteristic adjustment button for 2 seconds to check if the output becomes 4 mA. The transmitter with the meter will display “ZEROPASSâ€.
4, differential pressure transmitter:
(1) *** Position adjustment screw and span adjustment screw Do not make a mistake. Do not adjust the range of the differential pressure transmitter at the installation site;
(2) When the differential pressure transmitter is adjusted, the temperature of the positive and negative pressure chambers and the pressure pipes on both sides must be the same. If there is a temperature difference on both sides, the adjustment characteristics will drift between the two;
(3) If the transmitter is used for positive and negative migration compensation at the site, the *** position adjustment should be made in the state of operation and transportation. If the amount of migration is too large, the migration compensation can no longer be performed on the differential pressure transmitter.
5. Precautions for pressure transmitter in daily use:
(1) Do not apply voltage higher than 36V to the transmitter, resulting in damage to the transmitter;
(2) Do not touch the diaphragm with a hard object, resulting in damage to the isolation diaphragm;
(3) The measured medium is not allowed to freeze, otherwise the sensor element isolation diaphragm will be damaged, resulting in damage to the transmitter. If necessary, the transmitter should be temperature-protected to prevent freezing;
(4) When measuring steam or other high temperature medium, the temperature should not exceed the temperature limit of the transmitter when used, and the heat sink should be used above the temperature limit of the transmitter.
(5) When measuring steam or other high temperature media, use a heat pipe to connect the transmitter and the pipe together, and use the pressure transmission transformer on the pipe. When the measured medium is water vapor, an appropriate amount of water should be injected into the heat pipe to prevent the superheated steam from directly contacting the transmitter and damaging the sensor;
(6) In the process of pressure transmission, the following points should be noted:
a. Connect the transmitter to the heat pipe, do not leak air;
b. Before starting to use, if the valve is closed, the valve should be opened very carefully and slowly, so as to prevent the measured medium from directly impacting the sensor diaphragm and damaging the sensor diaphragm;
c. The pipe must be kept clear, deposits in the pipe will pop up, and the sensor diaphragm will be damaged.
6, the conclusion
In the process of using the differential pressure transmitter, it must be installed, wired, adjusted, and adjusted in strict accordance with the requirements, and put into operation in the correct way. Only in this way can the measurement be accurate and reliable.
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