Temperature sensor Product information

Temperature sensors become the Temperature measurement used. In conjunction with a Temperature controller the temperature of gases or liquids can be monitored and controlled. The sensors are available in the following variants Resistance thermometer and Thermocouples available and convert the temperature into a measurable signal. The most common measurement methods are via an electrical resistance or electrical voltage.

Resistance thermometers use the electrical resistance of metals to measure temperature and are often used at temperatures from -200 °C to +850 °C. Resistance thermometers are particularly preferred at low temperatures because their accuracy is higher than that of thermocouples. Thermocouples use the electrical voltage from a pair of different metals to measure temperature and are used at high temperatures.

Factors influencing temperature sensor measurement accuracy

For temperatures up to +500°C standard probes are used and for temperatures above +500°C special probes are used. The probe length should be considered according to the maximum immersion depth, as measurement errors can be caused by heat transfer along the thermowell. For accurate measurement, the immersion depth of the temperature probe should not be less than 10 times the outer diameter. The flow velocity of the medium in which the probe is located is also a factor that affects the measurement sensitivity. In general, R/T should be perpendicular to the direction of flow.

Temperature sensors in different designs

Depending on the application and mounting requirements, temperature sensors are available in different designs. With a Immersion sensor the sensor is encased in an immersion sleeve. The sensor is immersed in the medium to be measured, gas or liquid. Bayonet probe are equipped with a bayonet lock and a pressure spring. With this fastening system, the sensor can be installed quickly and replaced quickly in the event of a defect. The pressure spring is used to adjust the installation length. Bayonet sensors are used, for example, in tools or injection moulding machines. Surface sensor are equipped with a flat sensor head which is attached to a surface by means of screw mounting. These sensors are used to measure the temperature of surfaces or enclosure walls, for example. With a Threaded probe the sensor head is equipped with a thread for mounting. With this type of mounting, the sensor is attached to the outside of an enclosure, for example, to measure the temperature inside. With a Angle sensor the sensor head is arranged at a 90° angle to the mounting device. Similar to a threaded sensor, this is attached to the outside of an enclosure to measure the temperature inside. Due to the 90° angle, this temperature sensor can be installed very flat. It is attached by means of screw mounting. With a Magnetic sensor the sensor head is magnetic. This offers the advantage of attaching the sensor to metallic surfaces without having to drill holes for screw mounting. Furthermore, the sensor with magnetic mounting can also be attached only temporarily or at different locations. The sensor head from Pipe contact sensors is equipped with a screw clamp and is attached to pipes or rods by means of this.

 Temperature sensor application areas

Temperature sensors are used in a wide range of applications. In the industrial sector in particular, these are used to control processes such as the Oven control or to the Control of the room temperaturer, such as in cold storage rooms. Here, the measured temperature value is transmitted from the sensor to a temperature controller which controls the system. Another area of application is the monitoring of machines to protect them from damage due to overheating. Likewise, in production processes, materials that should have a certain temperature are measured with a temperature sensor and the temperature is controlled accordingly. For example, in injection moulding machines for the moulding of plastic parts, the plastic granulate is heated to the appropriate setpoint in order to liquefy and then pressed into the mould. In thermoforming, on the other hand, the material to be moulded is heated and drawn onto a mould with the aid of compressed air or vacuum. Here, too, the temperature of the moulding material is monitored by means of a temperature sensor.