What problems should be considered when choosing temperature and humidity sensors? The choice of temperature and humidity sensor is mainly based on the measurement range. The platinum resistance sensor can be used when the measurement range is expected to be within the total range. A narrow range usually requires that the sensor must have a fairly high basic resistance in order to obtain sufficiently large resistance variations. The large resistance variations provided by thermistors make these sensors very suitable for narrow measuring ranges. Thermocouples are more suitable if the measuring range is quite large. It is better to include the freezing point in this range, because the scale of the thermocouple is based on this temperature. The linearity of the sensor in the given range can also be used as an additional condition for the selection of the sensor.

In most cases, the selection of temperature and humidity sensors needs to consider the following aspects:

1) whether the temperature of the object to be measured needs to be recorded, alarm and automatic control, whether remote measurement and transmission are needed.

2) the size and accuracy requirements of temperature measurement range.

3) is the size of temperature measuring element appropriate?.

4) whether the temperature sensor delay can meet the requirements of temperature measurement when the temperature of the object is changing with time.

5) whether the environmental condition of the tested object is harmful to the temperature measuring element.

6) what is the price and the use is convenient?.

Response time is usually expressed by time constant, and it is another basic basis for choosing temperature and humidity sensor. The time constant is not so important when monitoring the temperature in the tank. However, when the temperature in the vibration tube must be measured during the process of use, the time constant becomes the decisive factor in choosing the sensor. The time constant of bead type thermistor and armoured outcrop thermocouple is quite small, while immersion probe, especially thermocouple with protective sleeve, has relatively large time constant.