Fluke Calibration 1620A DewK

Each DewK sensor measures air temperature and relative humidity. From those, the instrument also computes dew point, heat index, and rates of change for its on-screen statistics, but the integration records only the measured temperature and relative humidity. The derived quantities are display functions rather than separately logged channels.

They are the same controller fitted with different accuracy-grade sensors. The high-accuracy 'H' sensor reads temperature to ±0.125 °C over a 16–24 °C calibrated range and RH to ±1.5 %RH (20–70 %RH); the standard 'S' sensor reads temperature to ±0.25 °C over a wider 15–35 °C calibrated range and RH to ±2 %RH. Both operate over 0–50 °C / 0–100 %RH, with reduced (uncertified) accuracy of about ±0.5 °C / ±3 %RH outside the calibrated band.

The Thiamis driver talks to the DewK over its RS-232 serial port using SCPI-style commands: '*IDN?' to read the model and serial number (the instrument identifies itself with its Hart Scientific 'HART,<model>,<serial>' string) and 'FETC?' to fetch readings. It records one temperature and one relative-humidity value per poll; the DewK's second sensor input, its Ethernet jack, and the optional 2.4 GHz wireless modem are device features this integration does not use.

Every DewK sensor ships with a NIST-traceable, NVLAP-accredited certificate of calibration for temperature and humidity (As Found and As Left data at three temperature and three humidity points), and the instrument is Fluke MET/CAL compatible, so calibration laboratories use it to document and monitor environmental conditions to a defined, traceable uncertainty.