Surface Temperature Measurement Type for industrial applications. Surface contact sensors, such as back-of-module sensors, attach directly to a surface and measure the temperature via physical contact.

The four most common types of temperature sensors, ranging in responsiveness and accuracy from high to low are: Negative Temperature Coefficient (NTC) Thermistors. Resistance Temperature Detectors (RTDs) Thermocouples.

One of the most accurate temperature sensors is a resistance temperature detector, or RTD. In an RTD, the resistance of the device is proportional to temperature. The most common material for RTDs is platinum, with some RTDs being made from other metals such as nickel or copper.

ET241 series surface temperature sensors are designed for measuring temperatures on closed pipe systems or other round or flat surfaces. The sensor can be conveniently fixed with a hose clamp or M3 screw. Mounting with hose clamps avoids any mechanical preparation of the measurement site.

Indirect temperature measurement avoids disturbing flow of the medium and the measurement object is hardly affected by the low thermal mass of the sensor. On the other hand, lack of pressure and chemical effects ensures longer lifespan of the sensor.

It must be considered that large differences in temperature between the measurement medium and surroundings have a direct effect on the measurement result. In such cases, additional insulation around the sensor and the cable in at least 10 cm range is advisable. To improve heat transfer from surface to the sensor, heat-conductive paste can be supplied.