Three models of psychrometers for differential measurements are available - RH300, RH350, and RH401. In addition to differential measurements, they feature simultaneous viewing of wet bulb, dew point, relative humidity, and air temperature. Model RH401 incorporates a noncontact infrared thermometer to calculate the T1 (surface temperature)-dewpoint differential. The display can be switched to give readings in Fahrenheit or Celsius. A built-in RS232 interface, with optional RS-232 cable, using Windows® HyperTerminal software allows downloading data to a PC. An optional RH355 accessory kit is available which includes the RH350 psychrometer, two type K temperature probes, 33-percent and 75-percent calibration bottles, an RS-232 cable, four AAA batteries, and a carrying case.

Extech Instruments, 285 Bear Hill Rd., Waltham, MA 02451; 781-890-7440;

eProduct #194