Thermocouples measurement range

Many industrial processes require reliable and regular temperature readings. The Thermocouple sensor provides an answer to this need. It also makes it possible to measure large temperature beaches in various environments. There are 8 main Types of thermocouple, each dedicated to a specific measurement range. To deepen the subject of the thermocouples measurement range and help you choose your sensors. We will come back to the Thermocouple operation. We will then see all of its characteristics linked to the thermocouple measurement range.

The principle of the thermocouple sensor

THE Thermocouple sensor is a component of the thermocouple probe, a temperature measurement device. Its operation is based on the Seebeck effect. C’, That is to say that an electrical voltage can be noted when exposed to a temperature change. This voltage is then converted to ° C or in ° F via them Thermocouples conversion tables.

THE thermocouple contains Two wires of metals or alloys of conductive metals. They connect at one point and form an open loop. The electro-motor force (FEM) appears when the welding connecting the two wires is in the medium whose temperature is desired. The other ends of the wires make it possible to link to the measuring device. And this in terms of what is called cold or cold welding points. The conversion tables start from the principle that the cold point at the temperature of the water freezing point. Either 0 ° C or 32 ° F. If we cannot keep at this temperature, then we must measure this real temperature. It must then be taken into account to carry out a compensation calculation.

The large thermocouple measurement range makes it a popular sensor

It is the type of temperature sensor most commonly used in industry. It is robust, it offers good resistance to vibrations and good measuring precision. Its cost is low and it provides a quick response following a temperature change.

It is also popular because it is able to measure very low temperatures (like absolute zero) as very high. Chosen correctly, it allows raise temperatures with high precision With a minimum response time. Thermocouple is a contact probe, which can measure an ambient temperature as a surface temperature.

What determines the measurement range of a thermocouple?

The measurement range means the temperature amplitude that a thermocouple can measure. Also called measurement range, it varies depending on the Thermocouple type. We mainly speak of 8 types of thermocouples Because they are the most used. They are compatible in the European standard CEI 60584.1. This classification depends on the types of materials used in the manufacture of the probe.

Apart from the thermocouple materials and measurement beaches, Another element is specific to each type. THE conversion curves. These curves indicate the temperature corresponding to the electromotive force noted by the measurement instrument. The temperature is in abscissa and the millivolts are ordered. The link between the two do not evolve regularly, forming a curve.

The thermocouples measurement beaches by type

Each type covered by the European standard CEI 60584.1 is designated by a letter and the materials that compose it, the positive element being cited first.

Thermocouple Type K (Chromel / Slicel) has a measurement range from 0 to 1,100 ° C in continuous use. In intermittent use, this beach extends over a wide temperature range of -200 to 1300 ° C.
The sensor of Type J (Iron / Constantan) allows a measurement on a range of -20 to 700 ° C in continuous use and -180 to 750 ° C in intermittent use.
A thermocouple of Type t (copper / constann) Measure the temperature on a range of -185 to 300 ° C in continuous use and -250 to 400 ° C in intermittent use.
The thermocouple measurement range of Type E (Chromel / Constanan) East from 0 to 800 ° C in continuous use and from −40 to 900 ° C in intermittent use.
For the Type n (Nicrosil / Nisil), continuous use ranges from 0 to 1 150 ° C, the intermittent use of −270 to 1,280 ° C.
The thermocouple of Types S (Rhodied platinum 10 % / Platinum) in continuous use covers 0 to 1,550 ° C. In intermittent use, its measurement range goes from 0 to 1,700 ° C
THE Type R (Rhodié Platinum 13 % / Platinum) Can measure the temperature from 0 to 1,600 ° C in continuous use and from 0 to 1,700 ° C in intermittent use.
Thermocouple Type B (Rhodié Platinum 30 % / Rhodié Platinum 6 %) offers a range of measurement in continuous use of 100 to 1,600 ° C, in intermittent use from 0 to 1,800 ° C.

Understand the thermocouple measurement range to choose a probe

The choice of a type of thermocouple turns to the one that best meets the technical requirements of the project for which it will be used. It's necessary Coincide the optimal thermocouple measurement range with the temperature range to be measured.

As we have just seen, each type of thermocouple is associated with a continuous beach and an intermittent range of use. These indications mean that The sensor should be used moderately on the intermittent use range. Using the thermal probe prolonged on this temperature range is likely to alter it, no longer guaranteeing a precise temperature control. The continuous use range is therefore that to be taken into consideration in priority When you choose a temperature probe.

Determining the temperature range to be measured is also useful for Choose the tools associated with the measurement probe, like the Recording box for thermocouples. This device, which generally includes a digital display, stores temperature data and can take into account several thermocouples simultaneously.

In short, do not hesitate to Contact our sales team de Thermometre.fr dedicated to benefit from our professional advice.