65
Field Operation:
Always follow accepted safety precautions. Make sure that
equipment is in good operating order. Before connecting the
nurse tank to the applicator, check the electric shut-off valve of
the SprayMate II system for proper operation.
After changing nurse tanks or after other periods of long shut-
down, operate the system in MAN until the application rate
stabilizes. This allows the heat exchanger to reach operating
temperature before selecting AUTO. Erratic operation may be
experienced if AUTO is selected before operating temperature
is reached.
Manifold pressure is very important for good distribution of
NH3. Use barbed fittings with properly sized orifices or an
adjustable manifold to maintain adequate pressure. If manifold
back pressure is too low, proper cooling will not be achieved,
vapor bubbles will be allowed to enter the flowmeter, and
readings will be inaccurate. Typical manifold pressure ranges
from 15 to 60 PSI (1 to 4 bar) depending on application rates
and ambient temperature. If manifold pressure stops climbing
but FLOW RATE continues to climb, vapor bubbles are present.
In hilly or rough conditions the nurse tank dip tube will not
remain submerged, allowing extra vapor in the system. This
vapor is to too much for the heat exchanger to condense and
the system will exhibit erratic operation. If the dip tube remains
out of liquid, operation may appear to be normal, but the
system is simply metering vapor. If this occurs, you will notice
extremely low manifold pressure. Change tanks before the NH3
level is low enough to cause these problems.
In NH3 control systems, location of the frost build-up is an
indication of system performance. The NH3 kit will normally
have frost on the output side of the servo valve and in some
cases, a small amount on the bottom portion of the heat
exchanger. Frost before the servo valve indicates excessive
pressure drop in the delivery system or restricted vapor lines.
The strainer is a common source of excessive pressure drop and
should be cleaned regularly. AFTER COMPLETELY DRAINING THE
SYSTEM, remove the large plug and carefully clean the strainer’s
screen.Also, periodically check the vapor tubes for obstructions.
Additional Troubleshooting Tips for NH3:
see Troubleshooting section, starting on page 35.
Appendix G: SprayMate II - NH3 Specific
Field Operation - Troubleshooting for NH3
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