The chart below shows the average time response for the first of 7 time constants to achieve 0 to 100% step change. It does not matter if the change is from 0 to 100 C or 100 to 1000 C the time response is the same. The data shown is for the 1st time constant or 2/3’s step change. Each of the remaining time constants are the same, 2/3’s of the remaining change. You can see that since we are looking at increments of 2/3’s, we achieve approximately 98% of the step change rather quickly. Obviously, size is a determining factor as the more mass, the more time to see the temperature change. Keep in mind that the smaller the probe, the faster the time response at the expense of being a more robust design. Too small and the probe could fail early in a severe application so a balance must be drawn between time response and probe life.
Approximate response time in seconds.
Values are for 2/3 of total temperature change from 0 to 100% as measured in water.
20-awg bare wire junction measured in gas.
Outside Approximate Approximate Grounded Ungrounded
Diameter Wire Gauge Wall thickness Junction Junction
.020 38 .003 .02 .03 .040 32 .006 .04 .13
.062 28 .009 .22 .40
.090 25 .012 .33 .68
.125 22 .017 .50 1.10
.188 19 .025 1.00 2.30
.250 16 .033 2.20 4.10
20 awg bare wire junction .45
Additional Time Response Information can be found here http://www.temprel.com/time-response-information-42/ or by calling Temprel at (800) 582-5098.
