Donaldson Company, Inc.
24
Magnehelic Gauge
The Magnehelic is a differential pressure gauge
used to measure the pressure difference between
the clean- 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.
If unit is equipped with factory-installed pressure
taps, skip to Step 5.
2. Before drilling, place a piece of non-combustible
cloth over the filter opening in the clean-air
plenum to protect them from drilling chips.
3. Place a piece of wood behind the drill location
in the dirty-air plenum to protect the filters
from damage by the drill bit.
4. Mount the pressure tap hardware on the clean-
air plenum panel. Mount the pressure tap with
the tee inside the dirty-air plenum.
5. 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. Attach the
mounting bracket using three #6-32 x 1/4-in
screws supplied.
6. Mount the gauge and bracket assembly to the
supporting structure using two, self-drilling
screws.
7. 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.
8. Carefully remove the cloth protecting the
filters. Close access doors and tighten securely
by hand.
9. Zero and maintain the gauge as directed in the
manufacturer
s Operating and Maintenance
Instructions provided.
