Pressure transmitter principle, selection criteria and price factors

Pressure transmitter is a kind of sensor commonly used in industrial practice. It is widely used in various industrial automatic control environments. It is especially widely used in pipeline transportation sites such as petroleum and chemical industry.

In the procurement of many electrical and instrument materials, they are also commonly used items. In order to facilitate users to make less common-sense mistakes in the process of selecting pressure transmitters, and to correctly select instruments, this article will pass.

The principle of common pressure transmitters is analyzed, the selection of transmitters is analyzed, and the parameters that cause the price of transmitters to fluctuate are compared with the corresponding purchase cases in the past. Pressure transmitters often use high-precision.

The secret instrument equipment appears in the scope of purchase, and it often becomes the main purchase object of electrical instruments because of the large number of purchases and high prices. Therefore, the control of its price has become very important a little. Through the analysis of the principle of the pressure transmitter, and then understand the characteristics of its selection, through the actual procurement work experience, reasonably find out the factors that affect the price.

As a precision instrument, pressure transmitter plays an important role in the petroleum and petrochemical industry. The pressure transmitter can not only be converted into the expected demanded electricity through some common quantities, but also to amplify some commonly used quantities. In the current industries in various fields, from a functional point of view, transmitters can be divided into pressure transmitters, integrated temperature transmitters, liquid level transmitters, etc. in petrochemical

In the industry, pressure transmitters are often used widely and widely used as the main purchase object. This article will also take pressure transmitters as the main research object.

Transmitter, which will be explained and analyzed in the attached table later.

The main work of the pressure transmitter is to transmit the pressure signal commonly used in petroleum and petrochemical to electronic devices, and through AD conversion, it is reflected in computer operation. For example, taking water pressure as an example, to

The pressure signal of the pressure generated by the water pressure is transmitted to the electronic device, and the corresponding current is generated (the current of most transmitters is 4~20mA). Through the corresponding algorithm formula, after the pressure transmitter is converted

The current is also boosted by the increase in the pressurized signal generated by the pressure.

Macroscopically speaking, the pressure transmitter is a pressure measurement sensor to realize the size of the pressure, and then through the module circuit, AD conversion is realized to obtain the voltage within the available range or current. From a microscopic analysis, the pressure is reflected in the integrated silicon pressure components, forcing them to deform under pressure, causing the bridge to function, obtaining the corresponding voltage and current, and then passing through the amplifier circuit

The voltage and current obtained in the previous stage are amplified and converted into a voltage or current that can be used.

According to the angle of measurement, pressure transmitters can be divided into pressure transmitters and differential pressure transmitters. As the name suggests, the former is a measurement of pressure, the latter is a measurement of pressure difference,

However, pressure transmitters are not only able to use this function in principle, and can be derived from other indirect measurement quantities, for example, through two pressure transmitters or a differential pressure transmitter,

Measure the upper limit and lower limit respectively to obtain the difference of the electrical signal, which can reflect the level of the liquid level.

The power of the transmitter and the wide range of use

Pressure transmitters can be classified not only from the perspective of measurement use, but also according to the structure and scale of pressure transmitters. Since the pressure transmitter is in direct contact with the measured liquid medium, consider

When used in the petroleum and petrochemical industry, the liquid is often corrosive, which will cause damage to the precision instrument and cause follow-up work such as maintenance. For this reason, the pressure transmitter is divided into general and

Isolated. The general pressure transmitter is in contact with the measured medium through the inner membrane in the zero-protection transmitter cartridge, while the inner membrane of the isolated pressure transmitter is sealed with silicone oil, which is used as a protection

The protective liquid exists in the membrane box, and the outer membrane of the pressure transmitter is in contact with the measured medium. When the measured medium is pressurized on the outer membrane, the silicone oil protective liquid in the inner membrane transmits the pressure to the general membrane box.

On the other hand, compared with general pressure transmitters, the advantage of isolated pressure transmitters is that they will not block the diaphragm chamber of the pressure guiding tube. Because the measured medium often contains filthy substances, it will be blocked frequently.

The diaphragm box will crystallize even because the medium is detached from the transmitter, which will force the medium to be drawn out of the pressure transmitter, which will inevitably cause the pressure transmitter to fail to operate normally, or even

Large-scale paralysis, delays in construction. Usually the isolated pressure transmitter adopts the flange connection method, so that the sensing diaphragm of the isolated pressure transmitter enters the measured device, so that the blocking problem.

Problems and crystallization problems are effectively solved, so that the measured medium will not be extracted. The outer capsule and measuring capsule of this isolation type transmitter can be divided into remote type and integrated type from the connection form.

Two types. The remote transmission type means that the outer membrane box and the measuring membrane box are separated as a whole, connected by a capillary in the middle, which can be installed on the bracket with the transmitter, which is conducive to maintenance; the integrated isolation pressure.

The outer capsule of the force transmitter and the main body of the transmitter are integrated into a single body, which is integrally installed on the device. The connection method is more simple and easy, and the matching screw is reserved on the device and the isolated pressure transmitter pattern, just screw it together. Because of the above introduction, the advantages of isolated pressure transmitters cannot be questioned, and the same good products have different designs and processes, which leads to isolated pressure transmitters are three to four times larger than general pressure transmitters.

To sum up, it shows that the pressure transmitter is widely classified and there are many types. How to judge the price of a certain pressure transmitter has become the most important issue, which determines the price of the pressure transmitter.

The lattice factor is the key to this problem.