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How to select pressure sensors

Post: 2020-02-29

Pressure sensor in the purchase selection, I believe that sometimes you will encounter some white, is to some purchase need to know the parameters do not know, first of all, the pressure sensor by definition is used to measure the pressure of a kind of instrument.Simply put, the standard current of 4-20ma is transferred to the secondary instrument (intelligent digital display instrument) or DCL system to display PV value.In the purchase of pressure sensors need to provide installation, measurement is what medium ah, do not need to take the field meter head display.Hart coordination, 485 communication and so on.

1. What pressure medium is being measured

The medium directly determines the type of sensor, diaphragm type or threaded mounting.Viscous liquid, mud can plug the pressure interface, solvent or corrosive substances will not destroy the transmitter and these media in direct contact with the material.These factors will determine whether the selection of direct isolation membrane and direct contact with the media materials.So it's important to be able to say what medium is being measured.

2. What kind of output signal is needed

Transmitters generally have 4-20 ma outputs and 0-5 v outputs. The choice of the output depends on a variety of factors, including the distance between the transmitter and the system controller or display, whether there is "noise" or other electronic interference signals, whether the amplifier is needed and the position of the amplifier.MA output transmitters are the most economical and effective solution for many OEM devices with short distance between transmitters and controllers.

3. How high the accuracy of the sensor is required for the field environment

Accuracy is determined by nonlinearity, hysteresis, nonrepeatability, temperature, zero offset scale, and temperature effects.But mainly due to non-linear, hysteresis, non-repeatability, the higher the accuracy, the higher the price.Usually the accuracy of choice has 0.075%, 0.1%, 0.2%, 0.5% of these several points, usually domestic accuracy can reach 0.1%, imports can reach 0.075.

4. The measuring range of the transmitter is the maximum pressure

First determine the maximum measurement pressure in the system, which is the measurement range of the sensor.It is generally necessary to select a transmitter with a pressure range about 1.5 times larger than the maximum.This is mainly due to the fact that in many systems, especially in water pressure measurement and processing, there are peaks and continuous irregular ups and downs, such instantaneous peaks that can destroy pressure sensors.Continuous high pressure values or slightly exceeding the transmitter's calibration maximum will shorten the life of the sensor, which will also reduce the accuracy.A buffer can then be used to reduce the pressure burr, but this will slow down the sensor's response.Therefore, the pressure range, accuracy and stability should be fully considered when selecting the transmitter.Normal pressure sensors can carry up to three times the pressure.Excessive pressure may cause damage to the sensor.Excessive range selection will result in inaccurate or unresponsive sensor display when measuring the actual pressure value.Therefore, it is necessary to choose some parameters.