17
Donaldson Company, Inc.
Magnehelic
®
Gauge
The Magnehelic is a differential pressure gauge used
to measure the pressure difference between the clean-
air and dirty-air plenums and provides a visual display
of filter change requirements. The high-pressure tap is
located in the dirty-air plenum and the low-pressure tap
is located in the clean-air plenum.
1. Choose a convenient, accessible location on or near
the unit for mounting that provides the best visual
advantage.
2. Plug the pressure ports on the back of the gauge
using two, 1/8-in NPT pipe plugs supplied. Install two,
1/8-in NPT male adapters supplied with the gauge
into the high- and low-pressure ports on the side of
the gauge.
3. Attach the mounting bracket using three, #6-32 x 1/4-
in screws supplied.
4. Mount the gauge and bracket assembly to the
supporting structure using two, self-drilling screws.
5. 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.
6. Zero and maintain the gauge as directed in the
manufacturer’s Operating and Maintenance
Instructions provided.
1/8-in NPT x 90°
male elbow
clean-air plenum pressure
tap location
1/8-in NPT adapter
1/8-in NPT adapter
plenum tap location
3/8-in flat washer
1/8-in NPT coupling
mounting bracket
#6-32 x 1/4-in mounting screws
support structure
mounting surface
Magnehelic gauge
high-pressure port
low-pressure port
two, 1/8-in NPT
adapters
plastic tubing
two, 1/8-in NPT pipe plugs
two, self-drilling screws
1/8-in NPT x 90° male elbow
dirty-air plenum pressure tap location
3/8-in flat washer
1/8-in NPT adapter
1/8-in NPT x 90° elbow
static pressure tee
Magnehelic Gauge Installation
