Temperature Reaction Time
Introduction
Several measuring points are generally used when determining the response time. Each of them is a time period in seconds required for the sensor reading/output to reach x% of the total value change (difference in temperature).
A single time period is known as sensor response time (or thermal response time).
Percentage | Also used as | Specific term |
---|---|---|
50% | T50 or t0.5 | none |
63.2% | T63 or t0.63 | Sensor Time Constant (τau) |
90% | T90 or t0.9 | none |
99.3% | T99 or t0.99 | 5 times the Sensor Time Constant (τau) |
EXAMPLE: For a temperature sensor taken out of an ice bath at 0 °C into a room at 10 °C, it will take exactly: -T50 to reach 5°C -T63.2 (Sensor Time Constant) to reach 6.32 °C -T90 to reach 9°C -T99.3 to reach 9.93°C
Please note that T100 (or 100% of the final desired temperature) will never be reached because of the laws of physics.
Environment
All the reference data must be also related to the medium used for the test - you need to keep heat transfer and circulation in mind.
Most commonly found mediums:
Water with circulation of 0.2 or 0.4 m/s
Air with circulation of 1 or 2m/s
And others, any medium needed can be used for the test
Water will have a much faster response time and the faster the circulation, the faster the response time.
Overview of Simple Hardware devices
We are using 4 types of devices:
Device | SimplePack Temp | SimpleMeter | SimpleIndustry (internal probe) | SimpleIndustry (NTC on case) | SimpleIndustry (NTC on cable) |
---|---|---|---|---|---|
Sensor | MEMS | MEMS | MEMS | NTC | NTC |
Placement | Inside enclosed case | Inside case with air intakes | Inside enclosed case | On the case | On the pipe |
T63 (sensor only) | 15s at 1m/s airflow | 15s at 1m/s airflow | 15s at 1m/s airflow | 4s | 15s in water |
T50 (whole device) | 2min (water), 4min (air) | 1min (air) | 8min (air) | 2s | 12s in water |
T63 (whole device) | 3min (water), 5min (air) | 1.25min (air) | 10min (air) | 4s | 15s in water |
T90 (whole device) | 12min (water), 20min (air) | 5min (air) | 40min (air) | 20s | 1min in water |
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