Process Parameters, leading UK-based manufacturer of industrial temperature sensors, has released specifications for Pt100 Platinum resistance thermometers.

According to the company, the name of the product draws heavily from its characteristics, where Pt is the chemical symbol for Platinum. Similarly, the “100” in its name refers to the resistance value of the sensor at 0C.

The company explains that since resistance temperature detectors (RTDs) can be made of different materials, like nickel (Ni) and copper (Cu), and the resistance value can be 50?, 500? or 1000?, this provides a standardised naming convention.

In the specifications document, the company also talks about how a resistance thermometer works on the principle of electrical resistance changing with temperature.

For this temperature, the tolerance falls under Class B. The Pt100 Class B specification is the widest tolerance sensor supplied, according to the company.

The tolerance of the sensor is provided as a reference to a class rather than a percentage of a measurement or a scale. That is because the tolerance of this RTD is not constant. The accuracy is highest at 0C but goes down if the temperature goes above or below that value

The specification document goes on to explain more about Class B tolerance. According to the company, a Class B Pt100 sensor, at 0C, has a tolerance of +/-0.3C.

Since the tolerance is variable based on the temperature, at 100C, the allowable tolerance is +/-0.8C. Also, since the variation is linear, at 200C, the tolerance is +/-1.3C.

Unlike other types of temperature sensors, like the thermocouples or thermistors, the Pt100 does not necessarily have only two connection wires.

It is possible to connect the Pt100 with a two-wire connection. However, the company asserts, that this might introduce measurement errors due to the resistance of the lead wire.

A three-wire connection attached to one side of the measuring element can be useful in compensating for the lead resistance. The company does clarify that it is important that each of the three wires used in this case be equal in conductor size and length.

According to the company, the four-wire system provides the most accuracy. It claims that this is the only way to compensate for all lead resistance in the measuring system and that this is true even if the wires all have different resistance.

The document goes on to outline the operating temperature range of the RTD, along with the sensor housing requirements, materials of the housing, mechanical design of the sensor, depth of immersion of the sensor, and other operating conditions.

It also talks about the sensor cable specification, including the common cable types available with the business. The company can provide PVC, silicone rubber, PTFE and PFA, glass fibre, and stainless steel armour, among other cable materials.

Finally, the document explains that Process Parameters offers customised solutions for special applications; e.g., where metals of any kind aren’t suitable; operations in the dairy, brewing, beverage, pharmaceutical, or cosmetic industries where hygiene and sanitary standards are essential; and, cases where the connectors need to match the instrumentation.

In addition to the Pt100 RTD, Process Parameters offers a wide variety of temperature sensors. To view their full range, please visit

Process Parameters Ltd
[email protected]
Unit 3 Woodlands business park
Woodlands Park Avenue
United Kingdom

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