Great Plains NTA2007HD Operator Manual - Manual (Page 107)

Great Plains Manufacturing, Inc. Contents Index Troubleshooting 103
04/04/2011 Contents Index 166-283M
Magnehelic® Gauge Troubleshooting
If a Magnehelic® gauge does not read zero with the fan
off, inspect the gauge, and re-zero as needed.
Check for chamber and breather line problems before
re-zero. Re-zero cannot accurately compensate for leaks
and blockages.
Re-zero the Magnehelic® gauge on level ground with the
fan off, and if possible, under no-wind conditions. Turn
the set screw
on the meter face until it reads zero from
the tractor driver’s viewing position.
MetaData: End of Troubleshooting
Problem Cause Solution
Non-zero
with fan off Zero drift Re-zero per instruc-
tions below
Gauge
reading
lower than
expected Relief port plug
missing/damaged Replace plug
Breather line
blocked or kinked Clear breather line
Leak in sensing
line Check line to cham-
ber
Gauge damaged Check for loose
cover, damaged
O-ring
1
Null4:
Figure 88
Magnehelic® Gauge
31187
Port ID for Troubleshooting:
Over-pressure relief port (with plug in place)
Low-pressure port (breather/atmospheric pressure)
High-pressure port (from manifold chamber)
Alternate high/low ports are plugged.
Winter testing/maintenance advisory:
Gauge readings may be inaccurate or sluggish below
-7
°C (+20°F)
2
3
4
3
2
4
1