Life and function of temperature sensor

Temperature has a major impact on the function and working life of most electronic devices. This is especially true for electronic pressure sensors. This is why pressure sensor specifications generally include the sum of values u200bu200bused for operation, storage, and compensation of the temperature of the medium. Exceeding these ranges can introduce unexpected errors in pressure readings, or in extreme cases, lead to failure of the completed instrument. Another temperature specification-calibration temperature-can also be included in the data sheet.

Operating temperature range is pressure sensor

The 'operating' or 'ambient' temperature range of
means that the low and high temperature transmitter body will be exposed during operation. For example, -20 to +80°C is the typical operating temperature range for standard pressure transmitters. If the temperature of the transmitter housing falls outside this range, the output signal may show extreme drift or the transmitter may stop operating completely. Even relatively brief exposure to temperatures outside the specified range can cause permanent damage. This is why it is important to verify the extreme environment of each application in order to select an appropriate pressure sensor.

Other factors may affect the operating temperature of the transmitter. If the transmitter body is made of metal and measures warm or thermal media, the heat will also be carried out when connected to the transmitter by this method. For example, this can allow a transmitter with a rated current of at least -20 to operate in a colder environment, which will 'warm up' through heat conduction from the process medium.

Another factor to consider is the cable. Many cable materials become stiff and fragile. Exposure to extreme cold may cause the cable insulation to crack if bent in an extremely cold environment.

Storage temperature

When storing temperature, it is usually also provided. In most cases, the storage range is wider than the operating temperature range. Electronic circuits are usually inoperable when they are not easily damaged by excessive temperature. The rated storage temperature specification may actually be less than the operating temperature range if the manufacturer includes launch packaging and testing to simulate transportation. For example, foam packaging may drop more than 100 OC (212OF).

Medium temperature

The temperature range of the media is another important indicator to be considered when selecting a pressure transmitter. The temperature of the media directly affects the overall performance and accuracy of the pressure sensor's readings. The temperature range of the transmitter and the media must be carefully selected, which is greater than the expected temperature of the media. Exceeding the temperature index of the media may cause errors or complete failure of the instrument.

A typical medium temperature range is specified as -30~+100℃. However, many transmitters have specifications for high-temperature media, and there are many options that can be used to handle the extreme temperatures of the media. These include a built-in cooling and metal fin elements provided as a medium for convective cooling before reaching the pressure sensor. The siphon can be used to measure the pressure of high-pressure steam. Even higher temperature ranges are possible when using a diaphragm seal and capillary. Diaphragm seals are often used when measuring the pressure of high-temperature media. The function of the seal is to isolate the medium from the transmitter and the capillary, which can be several feet long, and to provide isolation from extreme temperatures.

Temperature compensation range

A 'compensation temperature range' specification is typically set in most cases. Compensated temperature is where the internal circuit of the sensor is designed to limit the temperature error to a specified level. For example, a pressure transmitter can have a temperature range of -30 to +100°C for the medium. The temperature range of compensation can be limited to -0 to +80°C, where the temperature error will not be greater than, say that 0.2% of the span is within this range and changes every 10°C. The temperature error outside the compensation range will be greater. As a rule of thumb, the compensation range outside the temperature error (but still lower than the medium temperature) can be up to three times the compensation range calibration temperature

Then, the calibration temperature is also defined in the specifications. This is when the transmitter is exposed to temperature during the calibration process in the manufacturing process and is used as a starting point to calculate the error within the 'compensated pressure range' mentioned above. The calibration temperature provided by some pressure transmitter manufacturers is an option for special applications. For example, the pressure transmitter has been calibrated to a standard temperature of 15-25oC. If the transmitter is operated within this range, no additional temperature error is introduced. If the application is called a constant temperature of 80°C, the transmitter can be factory calibrated at this higher temperature. This provides users with improved transmitter performance in high temperature applications.