PURCHASING GUIDE FOR PYROMETERS AND COMBINED DEVICES (PYROMETERS + PRESSURE GAUGES) FOR KARTING

Luca Barnaba

25 March 2022

When it comes to tyre temperatures, it is essential to have the right measurement tool for your needs. There are many products available (9 products considered by us) which vary, both in terms of prices (from 70 to 600 Euros) and functionality (detection of only temperature rather than temperature/pressure). Without forgetting the technology: infrared or probe. Are you confused enough? Let's try, then, to shed some light on this

WHAT YOU SHOULD KNOW

“Having a pyrometer is the first step in solving a problem”: Pascal Cardinale, owner of Prisma Electronics, introduced us to the correct temperature management of kart tyres in this way. A vast and complex world, in which technical knowledge must be combined with the right instrumentation. Here are some elements to choose the one that suits you best.

Why buy a pyrometer?

Temperature is the "coded" language through which tyres communicate fundamental information about: pressures, set-up and other aspects relating to the use of a kart. This is why it is essential to have a device capable of reading these messages: the pyrometer. those used in motorsport are exclusively digital and differ in the data detection technology used: infrared or probe. These two detection methods are in most cases complementary, since they respond to different needs: infrared pyrometers are more often used for analysis on large areas of the tread, while probe pyrometers allow the study of a specific area of a tyre. The pyrometer market has wide price ranges: good infrared pyrometers can be purchased with budgets from 100 to 150 Euros (in this case it is essential to make sure that the device is suitable for use in motorsport), while for probe pyrometers, the price ranges are approximately double, from 200 to 300 Euros. Regardless of the device you choose, when it comes to temperatures and their management, however, it is good to adopt a well-defined working method, an aspect that you can learn more about in the article “Tips from the experts - Practical advice for managing the temperature of kart tyres”

Infrared

Infrared pyrometers use an electrical sensor to transform the radiation emitted by a hot body into temperature data. This favours detection speed, on average 0.25 sec, because it is enough to point the sensor towards the surface keeping it at a reduced distance from it, but it also limits its field of application: in fact, analyses relating to the temperatures of tyres undertaken by using these instruments concern the surface temperatures detected on the tread which, in some cases, can be affected by the radiation emitted by the rims, brakes or even by fragments of tyres collected on the track, sometimes giving inaccurate results.
This is why, when buying an infrared pyrometer, it is essential to know the FOV (field of view) of the sensor to know exactly at what distance to position the sensor in relation to the area of the tyre to be analysed, in such a way as to minimise the effects of other heat sources that can affect the accuracy of the data collected. The use of these instruments can be a good approach to temperature measurment, both for their ease of use and for the relatively lower costs compared to probe devices.

Probes

Needle pyrometers exploit the contact between a needle probe and an object to detect temperatures through a thermocouple, making them more functional when you wish to analyse a precise point on a tyre. However, this implies a slower detection capability (2-3 seconds) than infrared pyrometers. In fact, probe pyrometers collect the data of the highest temperature captured during the detection period, therefore a time interval that depends on the construction qualities of the pyrometer. Furthermore, these devices must be associated with a correct (and slightly longer in terms of time than that to be implemented with infrared systems) method of use: in fact, for measurement to be correct, care must be taken to insert the probe perpendicularly in the tread to a depth ranging from 3 to 5 mm (to know the procedure in detail, read “Tips from the experts - Practical tips for managing the temperature of kart tyres”): it is not enough, therefore, as happens with infrared systems, to quickly "identify" the measurement area. Finally, probe instruments can be fragile and less manageable both because it is very easy to break the tip of the probe and because the latter is usually connected to the main computer by cable and can get in the way during the most lively phases on the track and in the pits. The high degree of precision, understood as awareness of the area under analysis, offered by these instruments (higher than that of infrared systems), however, is essential when a few tenths of a degree can make the difference between winning or losing a competition.

8 PARAMETERS TO HELP YOU CHOOSE

Thus, ultimately, how can you choose the right device? what should the choice be based on? Here are the 8 fundamental elements.

1. As already mentioned, the technology: infrared or probe (with the relative strengths and weaknesses, already described, that distinguish them).

2. If you opt for the former, be aware that it will be essential to evaluate the FOV, that is the field of view (15°, 20°, 35°…) within which the infrared sensor is able to detect the surface’s temperature to be measured. In fact, the data on the temperature will be provided according to the average temperature detected by the sensor itself in that area. For complete information, you must always consider what the relationship between the distance from the object and the surface being analysed is for each field of view. It goes without saying that the wider the sensor, the larger the portion of tyre being analysed, maintaining the same distance. Analysing the tyres’ temperature is an operation that requires precision, so it is mandatory to always know what you are analysing.

3. Detection speed of the device, because sometimes even one second less per detection (since a number of measurements are carried out per tyre and on a total of 4 tyres), it can make the difference.

4. Error percentage of the device, to understand if the accuracy of the instrument coincides with the level of accuracy needed for your competition level.

5. Range of temperatures detected, to ensure that the temperatures at which your tyres “travel” are measured.

6. Length of the cable for probe pyrometers (and replacement costs of the same in case of breakage), so as to evaluate practicality of use.

7. Source and duration of the instrument's power supply (internal rechargeable, disposable battery, etc.), again to understand its practicality.

8. Data storage capacity, in order to understand whether the memory has enough space for your needs.

* For infrared pyrometers In case you opt for an infrared pyrometer, it’s good to bear in mind that once the FOV angle has been established, the pyrometer will detect an increasingly larger portion of the surface as you move away from the surface itself with the pyrometer. Therefore, make sure that the FOV is completely directed to the tyre’s tread.

** For probe pyrometers

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