Temperature measurement

Temperature measurement explained plain & simple!

A Thermocouple Thermometer can most easily be referred to a as a temperature measuring device. More often than not you will see them as a meter reader unit with two temperature probes attached on flexible wires.

How does temperature measurement work?

The process of action for Temperature measurement works by having two different conductors at sensitive points of thermo probes. The reactive temperatures will differ from what is programmed as a reference temperature at other points of the circuit unit. This allows the thermocouple to produce a voltage charge when the reactive temperature differs from that of the reference temperature threshold.

These probes are usually supplied to conform within a designated humidity or moisture measuring range, however as most modern units are interchangeable anyway this allows for a high degree of customization.

When compared against other forms of moisture and humidity measurement Thermocouples display impressive performance characteristics. Mainly due to fact that they are portable and self – powered. Other measuring approaches usually require large power and excitation commitments. The main weakness however for Thermocouples is that they are only usually accurate to within one degree Celsius, however this can be achieved with some newer models and technologies.

What are they used for?

Most commonly thermistors and thermocouples are used for science and industrial applications. Measuring the temperature of engines and turbines is a common usage as well as them being suitable for use as temperature measurement components. Uses also extend to fire and Safety where appliances that monitor heat intensity are measured for optimal performance.

It’s also worth mentioning that for different industries and the desired temperature ranges – different reader probes are often used. Each moisture probe will be constructed from specific metal alloys that will have a recognised relationship between the temperature that is recorded and the voltage created by this.

Lifespan

With regards to their lifespan this heavily depends on usage rather than what substance is to be actually monitored. As often they are used to record high temperatures this inevitably speeds up the aging process.
Primarily this is due to the changing sensitivities of the thermoelectric wires which results in a mismatch with the programmed measurement voltage.

Also if they are exposed to continual high temperatures or volatile chemical substances they can lose their homogeneity due to metallurgical changes that occur. Put simply the metal humidity probe will change to some extent physically/structurally. Accurate Temperature measurement becomes difficult here.

Some Thermocouple sensors can be maintained to some extent. As using correctly calibrated thermometers is essential we recommend the ice bath method to increase longevity and maintain measuring accurate thermometer readings.

The ‘Ice bath’ immersion technique

This is a relatively simple technique whereby the junction block of the thermocouple or thermometer is completely immersed in a part-frozen bath of distilled water. Normal atmospheric conditions are fine for this with the melting point acting as a naturally occurring thermostat. You must of course know the reference junction temperature before you conduct this as it will determine correct calibration.

Most commercial units supplied are economical to be used for in most industries as well as many models being supplied for specifically for domestic use.

Valdamark supply market leading Cooper Atkins Temperature measurement equipment. These high performance humidity and temperature monitoring instruments are a ‘best in class’ range consisting of Infrared Thermometers, food thermometer probes as well as temperature probes and wireless digital data loggers.

For more information on temperature measurement visit our partners site.

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