1
PRELIMINARY EXAMINATION
Remove the instrument from the packing
material and examine it carefully to make
sure that no damage has occurred during
shipment. If noticeable damage is found,
immediately notify your Dealer.
Note: Conserve all packing material until
the instrument has been observed to
function correctly because all defec-
tive items must be returned to the
Dealer in their original packing.
HI 8666 is a 2-wire, 4 to 20 mA relative
humidity and temperature transmitter. The
instrument transmits electrically isolated out-
puts that are linear and proportional to RH%
and °C. It can be surface or panel mounted,
and used with a detachable connector. The
power must be supplied from an external
source from 12V to 24V. See the diagrams
on pages 4-6 of this instruction manual for
connections from the transmitter to other
equipment, such as recorder.
Note: After 30 minutes of measurements
over 90% RH, the probe sensors could
experience secondary absorption,
leading to approxi6% RH
saturation. This means that the read-
ings will be inaccurate. To restore
the probe to a normal condition, place
the probe into the LiCl well of HI 7102
for 24 hours (see page 7).
GENERAL DESCRIPTION
