The Fieldpiece ARH4 Digital Psychrometer Accessory Head measures both relative humidity and ambient air temperature. It calculates dew point and wet bulb. It’s great for calculating target superheat as well as logging %RH, temp, WB or DP over time. The head converts %RH, ambient temperature, dew point temperature, and wet bulb temperature to a voltage at a rate of 1 %RH or degree to 1mVDC and your reading is displayed on your meter. The ARH4 snaps directly onto Fieldpiece stick meters, data logger, electronic handles and adapters.

The ARH4 employs an advanced pair of sensors, a thermistor and a hygrometer, that sense temperature and moisture in the air. With built-in psychometric charts, the ARH4 calculates dew point and wert bulb based on these direct measurements. For the most accurate readings, expose the ARH4 to the air you are measuring for a few minutes so that the sensors can come to equilibrium.