The Validyne Model DR800 Draft Range Transmitter is
designed exclusively for very low pressure
measurement needs. It has a “true” full-scale range as
low as ±0.25” H2O, making it ideal for air flow control
applications. It can be turned down to ±0.1” H2O;
higher full-scale ranges to ±100” H2O are available.
The DR800 offers 0.5% accuracy and an operating
temperature range of -20°F to +185°F. The total
combined temperature effects are less than 3%/100°F.
Validyne has simplified the zero and span
adjustments. The Model DR800 uses a
programmable circuit board jumper in
conjunction with a 20-turn potentiometer to
achieve a smooth, accurate zero adjustment.
Using the pot/jumper combination, ranges can be
selected from –100% zero elevation to +85%
zero suppression (see Fig. 1). Also, the span
adjust has a HI and LO gain jumper to allow
better full-scale set-point resolution. This achieves
more turns from the potentiometer over a smaller
percentage of the span and zero adjust range
making critical set-point calibrations easier and
less time consuming.
The DR800 has been designed for easy field repair
if required. All the electronics are housed in the
NEMA housing on top of the transducer and joined
to the transducer through a single plug in the neck of
the transmitter. The entire electronics housing can
be removed and replaced in a matter of minutes
without removing the transducer from its mounting.
The electronic circuit board is also field repairable;
no special tools are required.