How to choose a pressure sensor

Pressure sensor is the most commonly used sensor in industrial practice. It is widely used in various industrial self-control environments, involving water conservancy and hydropower, railway transportation, intelligent building, production automation, aerospace, military, petrochemical, oil well, electric power, ship, machine tool. Pipes and many other industries, the following is a brief introduction to how to choose a pressure sensor.

1. What kind of pressure should be measured by the pressure transmitter?

First determine the maximum value of the measured pressure in the system. Generally, you need to select a transmitter with a pressure range that is about 1.5 times larger than the maximum value. This is mainly due to the fact that in many systems, especially water pressure measurement and processing, there are peaks and constant irregular up and down fluctuations, which can damage the pressure sensor. A sustained high pressure value or slightly exceeding the transmitter's calibrated maximum will shorten the life of the sensor, which will also reduce accuracy. A buffer can then be used to reduce the pressure glitch, but this will reduce the sensor's response speed. Therefore, the pressure range, accuracy and stability should be fully considered when selecting the transmitter.

2. What kind of pressure medium

Viscous liquids and mud can block the pressure interface, and solvents or corrosive substances will not damage the materials in the transmitter that are in direct contact with these media. These factors will determine whether to choose a direct barrier and a material that is in direct contact with the media.

3. How much accuracy does the pressure transmitter need?

Determine the accuracy, nonlinearity, hysteresis, non-repetition, temperature, zero offset scale, temperature effects. But mainly by nonlinearity, hysteresis, non-repetition, the higher the accuracy, the higher the price.

4, the temperature range of the pressure transmitter

Usually one transmitter will calibrate two temperature segments, one of which is the normal operating temperature and the other is the temperature compensation range. The normal operating temperature range is the temperature range when the transmitter is not damaged during operation. When the temperature compensation range is exceeded, the performance index of the application may not be achieved.

The temperature compensation range is a typical range that is smaller than the operating temperature range. In this range, the working transmitter will definitely meet its performance specifications. Temperature changes affect its output in two ways, one is zero drift, and the other is the full-scale output. For example: +/-X%/°C of full scale, +/-X%/°C of reading, +/-X% of full scale over temperature range, +/-X% of reading within temperature compensation range If there are no such parameters, it will lead to uncertainty in use. The change in the output of the transmitter is caused by a change in pressure or by a change in temperature. Temperature effects are the most complex part of understanding how to use the transmitter.

5. What kind of output signal is needed?

mV, V, mA and frequency output digital output, the choice of 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 an amplifier is needed, The position of the amplifier, etc. The most economical and effective solution for transmitters with mA output for many OEM devices with short distances between transmitter and controller.

If you need to amplify the output signal, it is best to use a transmitter with built-in amplification. For long-distance transmission or strong electrical interference signals, it is best to use mA-level output or frequency output.

In the environment with high RFI or EMI specifications, besides the need to note the choice of mA or frequency output, special protection or filters should be considered.

6. What kind of excitation voltage is selected?

The type of output signal determines how the excitation voltage is selected. Many pressure transmitters have built-in voltage regulation, so their supply voltage range is large. Some transmitters are quantitatively configured and require a stable operating voltage. Therefore, the operating voltage determines whether or not to use a sensor with a regulator. When selecting a transmitter, consider the operating voltage and system cost.

7. Do you need an interchangeable transmitter?

Determine if the required transmitter can accommodate multiple operating systems. This is generally important, especially for OEM products. Once the product is delivered to the customer, the cost of the customer's calibration is considerable. If the product is interchangeable, even changing the transmitter used will not affect the overall system.

8. The pressure transmitter needs to maintain stability after working overtime.

Most transmitters produce “drift” after over-exhaustion, so it is important to understand the stability of the transmitter before purchasing. This pre-work can reduce the hassle of future use.

9, the pressure transmitter package

The package of the transmitter is often overlooked as its frame, but this will gradually reveal its shortcomings in later use. When purchasing the transmitter, you must consider the working environment of the transmitter in the future, how to humidity, how to install the transmitter, whether there will be strong impact or vibration.

10. What kind of connection is used between the transmitter and other electronic devices?

Do you need a short distance connection? If a long-distance connection is used, is it necessary to use a connector?