Leiderdorp Instruments sell Pt-100's and so called smart temperature sensors.

Pt-100

A Pt-100 is a temperature dependent resistor. The resistance at 0°C is 100 Ohm. The temperature coefficient is approximately 0.38 Ohm/K. Pt-100's are used to measure temperatures of -200...+850 °C. Pt-100 sensors are available in a large number of different housings. Leiderdorp Instruments sell two shapes: needles for the measurement of the temperature of a fluid in a conduit pipe and clamp-on sensors for measurements at the wall of the pipe. These sensors can be used in the range -40...+200 °C.

Both types are available with a sensor element DIN class A or class 1/10 DIN B. Class A sensors have an accuracy that is described as follows:
maximum error in K = 0.15 + (0.002 x |T|) (|T| = temperature in °C without sign)
For class 1/10 DIN B this is:
maximum error in K = 0.03 + (0.0005 x |T|) (|T| = temperature in °C without sign)
This is conform IEC 751.

For measuring temperatures, see PRO-NET.

Pt-100 needles

These sensors have a cylindrical stainless steel housing. The diameter and length can be specified within the following range: diameter 3 - 6 mm, length 30 - 300 mm.

The cable length can be specified in the range 0.5 ... en 30 m. The sealing of the sensor on the cable is water tight. If a 4-wire configuration is used, the cable may be expanded virtually unlimited.

The mounting of the sensors can be realized in several ways: see 'mounting'.

As accessories, 3-6 mm reducers and 6-12 mm reducers are available.

Pt-100 clamp-on sensors

These sensors have a block shaped stainless steel housing. On one side they have a v-shaped groove so that the sensor can be clamped on a pipe.

The dimensions are 8 x 8 x 35 mm.

Smartec

The so-called Smartec temperature sensors are semiconductor sensors. The output signal can be processed very easy with a microcontroller. These sensors can therefore be implemented at very low cost in applications where there is a microprocessor present for other purposes. The sensors are available in TO-220 and TO-92 housing.

The sensors are powered with +5VDC. The output signal is a square wave from 1-4 kHz of which the duty cycle is a measure for the temperature of the sensor.

All sensors are equal. There is no individual calibration factor.

The PRO-NET data logger has very low cost inputs for Smartec sensors.