Knowlegde base...


With an experience of more than 70 years in designing and manufacturing of industrial temperature measurement technology, we have developed into one of the leading manufacturers of temperature, measurement and control equipment.
Today, with more than 100 employees and a product portfolio of more than 5,000 different temperature sensors, we produce  more than 20000 variations at the headquarter located in Troisdorf near Bonn.
With our  expertise, our know - how and our will, we fulfill all conceivable  temperature detection tasks from close to all branches of industry.
We solve daily highly complex tasks from the area of temperature,  measurement and control technology for the plastics, pharmaceutical,  food, raw material refining, metal processing, furnace construction,  waste management, automotive industry, plant engineering and mechanical engineering, glass and textile industries


Founded in 1946 as a handicraft company in Troisdorf near Bonn by Heinrich Gräff, the grandfather of today's managing director Marion Hupperich , the company  continued to develop and laid the foundations for today's product portfolio between the years 1962 and 1964 with the manufacturing of temperature sensors.
At currently  more than 2500 m², Gräff GmbH manufactures state of the art,
high-quality, precise and sustainable temperature measurement  technology, using
state of the art production facilities.
Today, our  product portfolio covers temperature sensors, control technology,  automation technology, actuators, electrical heating technology,  insulation technology and mass printing technology due to continuous  market observation.
As one of the  first manufacturers in the European market, our mass-pressure sensors  were tested according to current standards and certified by TÜV Rheinland.


The organizational structure of Gräff GmbH was designed specifically for optimal functionality and customer-friendly service.Clearly defined competences and flat hierarchies enable short decision-making  processes and quick reactions to all customer requirements and market  situations.










Platinum resistance thermometers have a high accuracy over a wide temperature range (from -200 °C to + 850 °C).
In its processing, pure platinum is specifically contaminated to maintain  the properties of the pure metal and make it more  resistant to chemical contamination during the measuring process, at the same time.
Unlike thermocouples, it is not necessary to use special wires to connect the sensor.


Resistance thermometers use the property of an electrical conductor to change the temperature of the electrical resistance.
The measuring principle of these sensors is to measure the resistance value of the platinum element.The most commonly used type (Pt100) has a resistance value of 100 Ohm at 0° C and 138.4 Ohm at 100° C.
Correspondingly, Pt25 / Pt1000 sensors have a resistance value of 5 Ohm and 1000 Ohm at 0 °C.
Platinum resistance thermometers are among the thermistors.In the case of a cold conductor, the resistance increases with increasing temperature.


Gräff GmbH offers platinum resistance thermometers of various tolerance classes.
Starting with tolerance class B (DIN EN 60751: 2008):
These sensors have an accuracy of +/- 0.3 °C at 0 °C..
For more precise measurements Tolerance class A (+/- 0.15 °C at 0 °C)
Or 1/10 DIN class B sensors (+/- 0.03 °C at 0 °C).
Please note that these tolerance values refer only to the pure temperature  sensor and possible errors in the overall measurement chain have to be  considered











A thermocouple is a pair of conductors of different materials connected  at one end. It is part of a device utilizing the thermoelectric effect for temperature measurement.
When a metal is heated, the electrons begin to migrate more and more, depending on the temperature. This results in a certain tension which also increases as a function of the temperature increase. When two different metals are used, the electrons move differently in each material. Two different voltages are now obtained. In the temperature measurement technique, the difference voltage of the  two materials is simply measured and compared to the temperature
This ratio is not exactly linear and must be calculated mathematically depending on the type of the thermocouple.
The reference point is the junction point of the thermocouple, which is at a  known (reference junction) temperature and is compared with the  measuring temperature.


Gräff GmbH manufactures all thermocouples using thermocable.
Thermocouples and compensating leads are used for the electrical connection between  the open ends of a thermocouple and the reference point.
Thermocouples are made with conductors with the same nominal materials as that of the corresponding thermocouple.
Compensation lines are made of conductors which have a different nominal material than that of the corresponding thermocouple.


Welded measuring point:
A measuring point which is electrically connected to the outer jacket.This results in improved characteristics in the response time of the sensor.

Potential free / insulated measuring point:
A measuring point which is electrically isolated from the outer jacket.




Knowledge base...

Gräff GmbH   Temperatur-,Mess- und Regeltechnik   Bonner Strasse 54   53842 Troisdorf  Germany

Phone +49 2241 4907-0   Fax  +49 2241 4907-66   Email