Dwyer MP - Manual (Page 2)

INSTALLATION
1. Location: Select a location free from excessive
vibration and where ambient temperature will be
between 20 to 120ºF (-6.7 to 49ºC). Pressure sensing
lines may be any length necessary without affecting
accuracy. However, long runs of tubing will dampen
readings slightly and cause an increase in response
time. If pulsing pressure or vibration cause excessive
pointer oscillation please contact factory for ways to pro-
vide additional damping.
2. Position: The Mini-Photohelic ® is calibrated and zeroed
with gage face in the vertical position at the factory. If the
gage is used in any other position, it must be re-zeroed
each time the position is changed. Gages with ranges
under 5 in. w.c. (1.24 kPa), or equivalent, should be
used only in the vertical position unless special calibra-
tion was specified when ordering.
3. Mounting: The Mini-Photohelic ® is normally mounted
before making electrical connections. Terminal blocks
are located on the rear of the gage for electrical connec-
tions.
(A) Panel Mounting: Standard installation for the Mini-
Photohelic ® mounting is flush through a panel.
Allow approximately 1˝ clearance for pressure tub-
ing and electrical wiring. cut a 2-5/8˝ (66.68 mm)
diameter hole in the panel. Insert the Mini-
Photohelic
® into the panel, thread #6 mounting
screws into the mounting lugs and tighten.
4. Zeroing: Before installation, the Mini-Photohelic ® may
need to be zeroed before placing into operation. If
zeroing is required, you must first remove the zero
adjust plug, located near the bottom face of the gage,
with a small blade screwdriver. (refer to Fig B.) The
zero adjust screw is located directly behind the plug.
Use the hex allen wrench supplied and adjust until the
pointer is on zero. This must be done with both pres-
sure connections vented to the atmosphere and the
gage oriented in the final mounting position. Replace
plug. Caution must be taken not to overtighten the
plastic plug when repluging.
5. Pneumatic Connections: To measure positive pres-
sure, connect tubing to port marked “+” and vent “–”
port to atmosphere. For negative pressure (vacuum),
connect to port marked “–” and vent “+” port to atmos-
phere. If gage is supplied with 1/8˝ male NPT connec-
tions careful attention must be made not to over-tight-
en fittings to avoid damage to the gage.
1 (25.40)
LOW PRESSURE PORT
HIGH PRESSURE PORT
2-19/32
(65.88)
3-1/16
(77.79)
1-7/16
(36.51)
2-3/8
(60.33)
23/64
(9.13)
1-15/16
(49.21)
11/64
(4.37)
5/32 (3.97)
MOUNTING HOLE
TYP 4 PLACES
2.276 (57.81) TYP
2-11/16 (68.26) SQ
Fig. A
ZERO ADJUST PLUG
Fig. B
PANEL MOUNTED
#6 MOUNTING
SCREW
MOUNTING
LUG
B-37-A:B-37-A 9/29/09 9:37 PM Page 2