To choose the right thermometer in Tunisia, you need to consider a number of key factors to ensure you have the right instrument for the right application.
Among these criteria, response time is a key element in the choice of your thermometer.
Reading speed, or "response time", is a very important factor when choosing a thermometer. Some thermometer technologies are faster than others, and depending on the application, extra seconds (or fractions of a second) can make all the difference.
Response time can be affected by many factors, including the position of the sensor relative to the substance being measured, the mass of the sensor itself, the speed of the processor doing the calculations, the length of wiring between sensor and processor, or the type of technology used.
In general, electronic thermometers are faster than mechanical thermometers (such as liquid mercury or dial thermometers).
Thermocouples are faster than resistance technologies (such as thermistor or RTD) and reduced-tip probes are faster than standard diameter probes (because the sensor is closer to the material to be measured and the sensor mass is smaller, and therefore more sensitive to temperature variations.
In catalogs and technical sites, including www.afrimesure.com, response time is often listed in increments called "time constants." It can be a little confusing, but a time constant is the time it takes for a given instrument to arrive at 63% of a complete reading. To get to a practical equivalent of 100%, four more time constants are needed - for a total of (5) constants to get an accurate temperature.
If a technical specification table lists a given probe as having a time constant of 0.5 seconds, you can expect to get a full reading with that probe at 2.5 seconds (or five times the listed time constant). This is important to remember, so you're sure to compare apples to apples when examining instruments with different specifications or brands.
Technical specifications, such as those on our probe selection pages, use time constants and will need to be multiplied by five to approximate the time for a full reading.
Another number that can be misleading is the "reading refresh rate." This number refers only to the rate at which a thermometer's digital processor samples from the sensor. temptest has a 0.5 second update rate. This means that the digital display shows changes in the temperature measured by the sensor every half-second, but this has nothing to do with how quickly the sensor adjusts the temperature of the material being measured.
Finally, as with precision, the "real" response time of a thermometer varies according to the particular substance, and the temperature range to be measured. Specification tables give outside limits, not exact speeds.
It's important to remember that - just as with accuracy - the total response time of a system (i.e. display and probe) may well be the sum of the response times of individual components (such as meter response time as well as probe response time).
This is one of the things that makes integrated systems like temptest and the PT100 precision thermometer attractive - response times are listed as a composite.
