Three categories of temperature sensors

Quite often we are asked which temperature sensors where to install. The question really takes time to study, because manufacturers around the world offer a wide range of devices for measuring temperature. The sensors have different designs depending on whether they are used to collect data in residential and office premises, technical premises (for example, entrances, basements, warehouses) or they are intended for industrial purposes – for example, to measure the temperature of the coolant.

Common areas

Room temperature control is unavoidable if you hope to reduce the cost of using electricity for air conditioning and heating systems. There are no special requirements for the technical characteristics of sensors in offices and living quarters, it is enough that they function in a familiar environment for people. For example, the Netvox R711 sensor measures temperatures in the range of -20 to +55 ° C, and also provides humidity readings of 10 to 90% with an accuracy of ± 4%. The R711 can be easily attached to a vertical surface with mounting or even double-sided tape, as it weighs only 140 grams. In addition, the device is powered by two standard AAA batteries (1.5V), so the number and location of sockets will not affect the installation.

R711

For those who prefer more complex solutions, you can choose temperature sensors combined with detectors of CO2 (carbon dioxide) and fine particles PM2.5. Such devices are popular among people who are concerned about air quality in rooms with large crowds of people – school classrooms, office space, conference rooms, hotel rooms, etc.

RA0715
Temperature and CO2 monitoring

Here is what the information from such a sensor looks like live:

Technical premises

If in offices and schools there are no special requirements to technical parameters of sensors, in cases with cellars and warehouses there are nuances. Increased humidity, dust and dirt, possible temperature changes and condensation on surfaces – all this can disrupt the operation of devices and affect the measurement performance. Here, the sensor housing must have a high level of protection to minimize the impact of the environment on the internal parts of the structure.

When measuring temperature and humidity inside refrigeration equipment, where the walls are made of metal and have a considerable thickness, it is very important that the radio signal passes outside for reception without interference. In addition, it is critical to mount the sensors, as any damage to the equipment walls must be avoided during installation. In such cases, you will find useful devices that operate in low temperatures (from -40 ° C) and are installed with a magnet. Among the Netvox range, the best option is the R718AB: it transmits a signal at 868 MHz and has a special Chirp modulation, through which the signal passes through metal walls.

R718AB
Protection level IP65

Industrial temperature measurement

Sensors in this group will be useful for diagnostic temperature measurements of industrial and other equipment. To do this, they are equipped with an external thermocouple based on a thermocouple, and each model is also presented with two measuring elements: copper-constantan, chromel-aluminum, nichrosil-nisil, and so on. For example, the design of a sensor with two elements is effective for condominiums, where there is a need to measure the temperature of the coolant at the inlet and outlet to the heating station to control the temperature of space heating.

R718CT Thermocouple sensor, range from -185 to + 300 ° C
R718CT2 Sensor with two thermocouples, range from -185 to + 300 ° C

The question arises: sensors with which thermocouples and where exactly to use? There is a lot of literature devoted to this topic, but for now we can summarize:

Thermocouple type T (R718CT or R718CT2) with copper-constantan TMKn temperature sensor is connected to measure the temperature in the range from −40 to + 125 ° C with an accuracy of ± 0.5 ° C
Thermocouple type K (R718CK or R718CK2) with chromel-aluminum THA temperature sensor have a measuring range from -40 to + 375 ° C with an accuracy of ± 1.5 ° C
Thermocouple type N (K718CN or R718CN2) with nichrosyl-nosyl TNN temperature sensor have a measuring range from -40 to + 800 ° C, with an accuracy in the range from -40 to + 375 ° C ± 1.5 ° C, and in the range from + 375 ° С to + 800 ℃ ± 1.5 ℃ ± 0.4%
Thermocouple type R (R718CR or R718CR2) with platinum-rhodium-platinum temperature sensor is connected to measure the temperature in the range from 0 to + 1100 ° C with an accuracy of ± 1 ° C

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