Downdraft Bench, DB-800
12
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 collector for mounting that provides the best
visual advantage.
If collector 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 and 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.
6. Attach the mounting bracket using three, #6-32 x 1/4-
in screws supplied.
7. Mount the gauge and bracket assembly to the
supporting structure using two, self-drilling screws.
8. 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.
9. Carefully remove the cloth protecting the filters.
Close access doors and tighten securely by hand.
10. Zero and maintain the gauge as directed in the
manufacturer’s Operating and Maintenance
Instructions provided.
Magnehelic
®
Gauge
Optional Equipment
Work Surface Rubber Mat
An optional 5/8-inch thick nitrile-rubber mat is available
for the Downdraft Bench. Used to protect the work piece
during buffing or grinding operations, the mat is oil,
grease, alkali and acid resistant, and suitable for aircraft
components.
