vacuum pressure transmitter and differential pressure transmitter difference between
As a precision instrument, vacuum pressure transmitter plays an important role in petroleum and petrochemical industry. Not only can be converted into the expected demand of electricity through some commonly used quantities, but also some commonly used quantities can be amplified. The main work is to transmit the common pressure signal of petroleum and petrochemical industry to electronic devices through ad Conversion is reflected in computer operation. For example, taking water pressure as an example, the pressure signal generated by water pressure is transmitted to electronic devices to generate corresponding current (at present, the current of most transmitters is 4 ~ 20mA). Through the corresponding algorithm formula, the converted current of pressure transmitter is also enhanced by the increase of pressure signal generated by pressure.
The pressure transmitter uses the pressure measurement sensor to realize the magnitude of pressure, and then through the module circuit, realizes AD conversion to obtain the voltage or current within the available range. Microscopically, the pressure is reflected in the pressure components of the integrated silicon, forcing them to deform under pressure, resulting in the action of the bridge to obtain the corresponding voltage and current, and then the voltage and current obtained in the earlier stage are amplified and converted into the voltage or current that can be used.
Vacuum pressure transmitter and differential pressure transmitter are often used in industrial production. Many new friends are not clear about the differential pressure and vacuum pressure, resulting in a lot of confusion in practical operation. In fact, this is the basic knowledge of pressure instruments, and it is a common sense that every relevant instrument must master. To understand the differences between these instruments, it is necessary to understand the differences between them, We need to clarify the differences between these concepts. The following is a detailed introduction by technicians:
1. Atmospheric pressure: the pressure produced by gravity in a column of air on the earth's surface. It is related to the altitude, latitude and meteorological conditions.
2. Differential pressure: the relative difference between two pressures.
3. Pressure: all pressures in the space where the medium (liquid, gas or vapor) is located. Pressure is pressure relative to zero pressure.
4. Gauge pressure (relative pressure): if the difference between pressure and atmospheric pressure is a positive value, then this positive value is gauge pressure, that is, gauge pressure = pressure atmospheric pressure > 0.
In short, ordinary pressure gauge measures gauge pressure, plus atmospheric pressure is absolute pressure. There are special absolute pressure gauges to measure absolute pressure. Take pressure at two different positions on the pipeline, the difference between the two pressures is the differential pressure, and the general differential pressure transmitter is used to measure the differential pressure. In many instruments, the transmitter is widely used. The transmitter is generally divided into vacuum pressure transmitter and differential pressure transmitter. The transmitter is commonly used to measure pressure, differential pressure, vacuum, liquid level, flow and density. The transmitter can be divided into two-wire system and four wire system, with two-wire system in the majority; intelligent and non intelligent transmitter are more and more.
The vacuum pressure transmitter and the differential pressure transmitter measure the difference between the pressure and the two pressures, but they measure many parameters indirectly. Such as pressure transmitter, in addition to measuring pressure, it can also measure the liquid level in the equipment. A pressure transformer is needed to measure the liquid level in an atmospheric vessel. When measuring the liquid level of pressure vessel, two pressure transformers can be used, i.e. one lower limit and one upper limit. Their output signals can be subtracted to measure the liquid level. Generally, differential pressure transmitter is selected. It can also be used to measure the density of the medium when the liquid level and pressure in the container remain unchanged. The measurement range of vacuum pressure transmitter can be very wide, from 0 to 100 MPa (in general). The selection of transmitter is usually based on installation conditions, environmental conditions, instrument performance, economy and application medium. In practice, it can be divided into direct measurement and indirect measurement; its uses include process measurement, process control and device interlock.