Selecting A Sensor
How Do You Pick a Sensor?
Choosing a temperature or moisture sensor can often be very straightforward, sometimes tricky, but always worth doing well. That’s because these types of sensors, especially those used in science and engineering, if selected and used correctly can spell the difference between repeatable results and nonsense numbers.
The name of the game in measurement is to measure a parameter with an amount of inaccuracy or uncertainty that is acceptable.
So, the first thing you need to know is how well you need to know the value of the temperature or moisture numbers you expect to get.
We’ve been updating a series of articles on a related website that delves into that in depth for nearly any type of measurement device, not just temperature and moisture sensors.
A simple series of questions, however, when answered, will often get you started down the right path.
1. What is the desired measurement range, the tolerable limit to the error in measurement and the conditions under which the measurement is to be performed?
2. Is it impossible or impractical to touch the object and, if so, would the sensor or the temperature of the object be likely to be seriously affected by the contact? (Would the sensor melt, exceed its upper measurement limit, etc..?)
If the answer is yes, then a noncontact temperature sensor is needed.
If no, then the answer probably lies with one of the other sensor types.
3. If a contact sensor appears satisfactory, then questions devolve to those about temperature measuring range, satisfying the conditions of use and meeting the acceptable error allowance.
Sensor Scientific’s web site has comparison of four popular contact temperature sensor types, Thermocouples, Resistance, Thermistors and Semiconductor, shown on a one page chart and in a very readable article.
Our companion website IRWeb.INFO, is focused on the subject of applications or uses of Thermal Infrared (IR) Radiation Thermometry and Thermal Imaging. It may well have some useful examples of noncontact temperature sensor use to help you in your search.
Another alternative is to study the pages and especially learn from the words and links presented here.
Our Uses page and subpages have some examples of successful sensor use.
When all else fails or you know you do not have time and or expertise sufficient to your task, consider contacting a measurement consultant at a testing lab or university or a specialist at one of the many sensor suppliers.
(See our linked pages for some leads in the three areas; Testing lab, University, Supplier)