
2019-04-12
417-459M
NP2540
Metering Overview
26
A16.Coupler Outlet Bleed Valve
This fitting is kept closed in normal operations. When
the breakaway is properly coupled, the inlet bleed
valve
bleeds the entire assembly, and applicator
supply hose. On breakaway, this valve is used to
bleed the applicator side of the disconnection.
A17.Supply Hose
This connects the breakaway coupler to the
emergency shut-off valve. Operator action is to
replace this hose, a time-dated part, when it reaches
the end of its operating life (see page 123).
A18.Emergency Shut-off Valve
The handle of this is valve has a rope which is routed
to the tractor cab (see page 36). Closing this valve
stops NH
3
flow to the cooler, metering system and
rows. There can still be a substantial amount of NH
3
in the system, for some time, with this valve closed.
See the “
Using Anhydrous Ammonia Safely
”
manual (407-551M) for emergency operation.
If the handle has a warning decal (page 14), the ball
may have a cavity that can contain a hazardous
amount of NH
3
if closed with the line full.
A19.Strainer
This filter contains a 20 mesh screen and two
ceramic magnets to remove debris from the NH
3
flow.
A20.Strainer Magnets
These capture ferrous metal debris of any size. They
need to be cleaned every 4 to 5 tank loads. See
A21.AccuFlow™ Super Cooler (Heat Exchanger)
For effective application, NH
3
needs to remain in the
liquid state until released underground. This is
accomplished by refrigeration. Some of the flow is
tapped
, fed back to the cooler at
, vaporized
and used to chill the fluid passing from
to
.
A22.Cooler Intake
Liquid NH
3
enters the cooler here.
A23.Cooler Hydrostatic Relief Valve
In normal operation, this valve never activates. NH
3
can get trapped in the system between the
emergency shut-off valve
and the On/Off
valve
, if both valves are closed while the system
is charged. As the liquid warms and pressure rises,
this valve protects the system with periodic releases.
This valve is set to activate at 350 psi, higher than
the nurse tank’s relief valve.
Operator action is periodic inspection, and to replace
this hydrostatic relief valve, a time-dated part, when
it reaches the end of its operating life (see
on page 121 for maintenance.
A24.Cooler Outlet
Chilled liquid NH
3
exits the cooler here.
A25.Flow Meter
This fitting converts fluid flow to pulses for the
SCS 450 controller. It has a range of 1-60 gpm. A tag
on the cable lead provides a “METER CAL” number
specific to the installed meter (and accurate only for
NH
3
fluid flow, and not NH
3
vapor flow).
A26.Drain Cap
The plumbing cross and lower cap below the
temperature gauge are provided to allow the gauge
probe to be exposed to the full NH
3
stream. This cap
does not require periodic clean-out.
A27.Temperature Gauge
This gauge reports the temperature of the chilled,
flowing, NH
3
. When NH
3
is not flowing, this gauge
slowly drifts up to ambient temperature.
Checking the temperature and pressure
gauges
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.
Normal field temperatures of the chilled flowing NH
3
are in the range 20 to 83°F (-7 to 28°C).
Suffocation, Blinding and Burning Hazards: