Install Instructions

INSTALLATION
LOCATION: Select a clean, dry location free from shock and vibration where temperature limits will not be
exceeded. Distance from the transmitter to the receiver is limited only by total loop resistance. See ELECTRICAL
CONNECTIONS. Tubing feeding pressure to the instrument can be practically any length required, but long lengths
will increase response time slightly.
POSITION: All standard models are calibrated for use in a vertical mounting position. Standard models will perform
properly at other angles but should be spanned and zeroed in the position in which they will be used.
WARM-UP: It is recommended to power up the DH3 unit and allow a 1-hour warm-up period before taking
measurements. This will stabilize the measurements and provide the best accuracy.
PRESSURE CONNECTIONS: For installation convenience two sets of 1/8˝ female NPT pressure ports are supplied.
Be sure to seal the unused ports with pipe plugs included.
Positive Pressure - Connect tubing to HIGH PRESSURE port and vent LOW PRESSURE port to atmosphere.
Negative (Vacuum) Pressure - Connect tubing to LOW PRESSURE port and vent HIGH PRESSURE port to
atmosphere. (When operating this device in a dusty environment, install an optional A-331 Filter Vent Plug in the
vented port to keep interior clean.)
Differential Pressure - Connect tubing from the higher source to HIGH PRESSURE port and from the lower source
to LOW PRESSURE port.
Figure A
1-1/2
[38.1]
5/16
[7.94]
11/16
[17.46]
3/4
[19.05]
1-3/32
[27.78]
1-3/4
[44.45]
1/2 [12.70]
(3) Ø3/16 [4.77] HOLES
EQUALLY SPACED ON
A 4-1/8 [104.78] B.C.
Ø1/2 [12.70] HOLE FOR
LOW PRESSURE CONNECTION
Ø1/2 [12.70] HOLE FOR
HIGH PRESSURE CONNECTION