Great Plains NP3000A Operator Manual User Manual
Page 28
24
NP3000 and NP3000A
Great Plains Manufacturing, Inc.
407-613M
2014-04-22
A28.Pressure Gauge
This gauge reports the pressure of the NH
3
after it
exits the cooler. If line valves are closed, a pressure
reading above zero indicates NH
3
is present
between the emergency shut-off valve
and the
On/Off solenoid valve
(the Control Valve
does not completely close).
Checking the pressure and temperature
against
the chart in the “Using Anhydrous Ammonia
Safely” manual (407-551M), or in the Raven
AccuFlow™ manual, indicates whether the flowing
NH
3
is in a liquid state.
When valves are open but NH
3
is not flowing, this
gauge normally reads within 5 psi of the nurse tank
pressure gauge
. If they are materially different
at zero flow, one of the gauges may be defective.
When NH
3
is flowing, the pressure reported by this
gauge
is lower than the tank pressure.
A29.Cooler Bleed Valve
This valve is normally closed. It is used to bleed
trapped NH
3
from the cooler system when valves
are closed. It can also be used to accelerate
clearing the cooler system for maintenance.
A30.Control Valve
This is a variable electronic valve controlled by the
SCS 450. It is the primary control point for
application rate. When power is off, this valve
remains at its most recent setting.
This valve has a visible indicator above the valve
ball casing, indicating whether open, closed or in
between.
When commanded to a rate of zero, this valve does
not completely close. Use shut-off valves to
completely stop flow. A full slew from fully open to
minimum takes approximately 9 seconds.
A31.Master Shut-Off Valve
This is the normal control for starting and stopping
total application flow in the field (for turns, etc.). This
component is an open/close solenoid valve
controlled by the “MASTER” switch on the SCS 450.
When power is off, this valve remains at its most
recent setting.
This valve has a visible indicator above the valve
ball casing, indicating whether open or closed.
Operation of this valve is essentially instantaneous.
Its valve ball is equipped with a downstream relief
orifice.
A32.Refrigerant Tap
A small amount of the NH
3
flow is taken at this point
to provide refrigeration at the cooler. There are no
operational items for this fitting.
A33.Refrigerant Line
This tubing passes tapped refrigerant NH
3
to the
cooler. Operator action is to replace this tubing,
a time-dated part, when it reaches the end of its
operating life. See page 115.
A34.Cooler Refrigerant Inlet
Tapped refrigeration flow enters the cooler at this
fitting, and is vaporized to chill the liquid entering at
fitting
. There are no operational items for this
fitting.
A35.Section Control Check Valve
(Section Control Option Only)
This prevents back flow when section shut-off
valves
are off with NH
3
present. There are no
operational items for this fitting.
A36.Section Control Bleed Valve
(Section Control Option Only)
This valve is normally closed. It is used to bleed
trapped NH
3
from the section control system if all
section valves
are closed.
Suffocation, Blinding and Burning Hazards:
See “About Bleed Valves:” on page 38.
A18
A31
A30
A27
A17
A28
Suffocation, Blinding and Burning Hazards:
See “About Bleed Valves:” on page 38.
A22
A39
A39