3
WIRING
DIAPHRA
GM
E
F
NEGATIVE ONLY
HIGHER NEGATIVE
LOWER POSITIVE
POSITIVE ONLY
LOWER NEGATIVE
HIGHER POSITIVE
Male externally threaded with nut and self-aligning ferrule.
Positive Pressure Only:
Connect sample line to E; F remains open to atmosphere
Negative Pressure Only:
Connect sample line to F; E remains open to atmosphere
Two Negative Samples:
Connect highest negative sample to F; lower sample to E.
Two Positive Samples:
Connect highest positive sample to E; lower sample to F.
One Positive and One Negative:
Connect positive sample to E; connect negative sample to F
Sample Lines
FILTER
Fan operation or true airfl ow
with little or no static pressure,
probe must be perpendicular to
fl ow.
Fan operation and true air fl ow
with varying amounts of static
pressure. Probe must be per-
pendicular to fl ow.
Fan operation or air fl ow with
no static pressure.
Suction or fan operation
Prove positive static pressure
Negative pressure increases as
fi lter gets dirty.
3 Ways to Prove Filter on Positive Pressure
Positive static pressure
Diff. across
Flow is reduced
increases as the fi lter
fi lter changes
as fi lter
gets dirty.
as it gets dirty
gets dirty.
Location of Sample Lines
Pressure Conversion Table
1” Water = .0361 lbs/sq. in. or .0735 in. Mercury
1” Mercury = 13.6 in water or .491 lbs/sq. in.
1 PSI = 27.7 in. water or 2.036 in. Mercury
