| The additional temperature probe is available for HMP155A and HMP155E. |
You can order the active output version of HMP155 with an additional temperature probe (T-probe). You can make relative humidity and additional temperature measurements with the additional T-probe, if you have a heated HMP155. The additional T-probe fulfils requirements of meteorological applications. The response time is faster in temperature measurement and it fulfils WMO requirement of 20-second time constant.
When the additional T-probe is in use, the relative humidity value is calculated based on the Td dew point value from the humidity probe and the Ta temperature value from the T-probe.
When you install HMP155 with the additional T-probe, make sure that the humidity probe and the T-probe are installed in the same conditions to get accurate readings. Even a slight difference in temperature conditions result in false RH readings. Install the probes so that the humidity probe does not heat the T-probe, but is close enough for the probes to share the same environment conditions. When an RH reading is required, always install the additional T-probe in the place where you need the reading from.
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You can calibrate the additional temperature probe in a liquid bath. |