35
Donaldson Company, Inc.
Photohelic Gauge Wiring Diagram
Photohelic Gauge in Optional NEMA 4 Weatherproof
Enclosure
Photohelic gauge
solenoid
valves
Pressure Switch
terminals
neutral
110-V
jumper wires
supplied by customer
timer
board
L1 L2
1 2 3
sol
com
L2
L1
HI
LO
C NO
NC
NC NO C
C NO NC NC NO C
Note:
For use with solid-state timer only. All parts, except
the mounting bracket shown in the Photohelic Gauge
Standard Installation drawing are included with the
NEMA 4, Weatherproof Enclosure.
Electrical installation, service,
or maintenance work must
be performed by a qualified electrician and
comply with all applicable national and local
codes.
Turn power off and lock out all power before
performing service or maintenance work.
Do not install in classified hazardous
atmospheres without an enclosure rated for
the application.
The Photohelic combines the functions of a differential
pressure gauge and a pressure-based switch. The gauge
function measures the pressure difference between the
clean-air and dirty-air plenums and provides a visual
display of filter condition. The high-pressure tap is
located in the dirty-air plenum and a low-pressure tap
is located in the clean-air plenum. The pressure-based
switch function provides high-pressure ON and low-
pressure OFF control of the filter cleaning system.
1. Choose a convenient, accessible location on or near
the collector for mounting that provides the best
visual advantage.
2. Mount the gauge to the remote panel or door using
the mounting ring, retaining ring, and four #6-32 x 1
1/4-in screws. Do not tighten screws. Connect two,
1/8-in NPT x 1/4-in OD male adapters to the gauge’s
high- and low-pressure ports. Tighten screws.
3. On the back of the gauge, remove four #6-32 x 5/16-in
screws and plastic enclosure. Set aside. Add two
jumper wires supplied by customer. Remove the
jumper from the pressure switch located on the timer
board, if equipped. Using the 3/4-in conduit opening,
wire the gauge as shown. Reassemble and fasten
enclosure securely.
4. Thirty-five feet of plastic tubing is supplied and must
be cut in two sections. Connect one section of tubing
from the gauge’s high-pressure port to the pressure
fitting located in the dirty-air plenum. Connect
remaining tubing from the gauge’s low-pressure
port to the fitting in the clean-air plenum. Additional
tubing can be ordered from your representative.
5. Zero and maintain the gauge as directed in the
manufacturer’s Operating and Maintenance
Instructions provided.
Photohelic
®
Gauge
6. To install the Photohelic Gauge mounted in a NEMA
4, Weatherproof Enclosure, follow Steps 4 and 5.
