Static pressure and one-way overpressure characteristics

(1) Static pressure characteristics.

Static pressure refers to the working pressure of the differential pressure transmitter, which is usually much larger than the differential pressure input signal.Generally speaking, the output of the differential pressure transmitter is only related to the input differential pressure, and has nothing to do with the working pressure of the transmitter. However, due to many factors such as design, processing, and assembly, the zero point and range of the transmitter vary with the changes with changes in static pressure.The static pressure index of the transmitter refers to the allowable range of this change. There are two points to note here:

①The output of transmitters with different ranges of use is not the same as the influence of static pressure. The range of the range is large, and the influence of static pressure changes is small; otherwise, the influence is large.In order to make the instruments produced by the manufacturer have higher technical indicators, no matter what measurement range the user uses, the static pressure indicator is always determined by how much the zero point and the range change under the maximum range.

②The static pressure of the transmitter can be positive pressure or negative pressure.Positive pressure has a limit, such as the most 16MPa, 40MPa; negative pressure also has a limit, such as -O.1MPa, but not absolute vacuum.When we talk about the static pressure of the transmitter, we usually only refer to its upper limit pressure, and the lower limit pressure seems to think that there is no regulation. In fact, this is wrong.When the transmitter is under absolute vacuum, the silicone oil in the membrane box will vaporize and damage the instrument, so there are also regulations.

(2) One-way overvoltage characteristics.

One-way overpressure is one-way overload, which means that one side of the differential pressure transmitter is pressurized and the other side is not pressurized.In the process of using the transmitter and the throttling device together, due to careless operation, sometimes the valve of one side of the pressure guide pipe is open, while the other side is closed, so the static pressure of the transmitter and the one-way overpressure will occur. pressure is the same.

For general instruments, the signal pressure can only be slightly larger than the rated pressure, such as 30% larger and 50% larger, but for differential pressure transmitters, the pressure of one-way overload is not slightly larger than the signal pressure, but larger Several times, dozens of times, hundreds of times.In this case, the transmitter should not be affected, and its zero drift must be within the allowable range, which is the unique one-way characteristic of differential pressure transmitters.

The earliest differential pressure gauges are not resistant to one-way overpressure, but the one-way overpressure index of the current transmitter is set very high, and one-way has basically no effect on the performance of the instrument.