Great Plains NP30A 30-foot Operator Manual - Manual (Page 26)

22 NP30A or NP40A Table of Contents Index Great Plains Manufacturing, Inc.
407-502M Table of Contents Index 2014-05-20
Systems Overview
This list describes a single-cooler system. A dual-cooler
system has two of components
through , and two
additional dual-tube knives or tines .
Refer to Figure 4 on page 21
A11.Acme cap
This captive cap protects the inlet when no nurse
tank is connected. NH
3
might be sealed behind this
cap.
A12.Acme inlet
The nurse tank hose coupler connects here and
must have 1
3 ⁄
4
-4 female Acme
a
swivel coupler. See
page 70 for nurse tank connection.
A13.Coupler Inlet Bleed Valve
This fitting is carefully opened at normal and
abnormal disconnects, to bleed NH
3
liquid and
vapor from the hoses (or to bleed just the nurse tank
hose upon breakaway). It is also opened prior to
Acme cap removal to verify that the line is
discharged. See “Making Nurse Tank
Connections” on page 70, “Unhitching Nurse
Tank” on page 79 and “Breakaway Event” on
page 77.
A14.Breakaway Coupler
This assembly is designed to separate and seal the
lines if between 300 to 400 pounds of pull force is
applied to the nurse tank hose. In normal
operations, this never happens.
Should the hitch fail, and both safety chains fail, or
an operator makes serious basic safety errors, the
breakaway separates to protect the hoses from
rupture. Spring-loaded checks inside the breakaway
seal both ends of the now-broken connection. If the
line was charged, 60 cc of liquid NH
3
is released on
breakaway.
Resetting a parted breakaway coupler is a complex
operation requiring tools. Consult the breakaway
manual for details. More significant matters are
safing the applicator and nurse tank, then correcting
the cause of the breakaway. See “Breakaway
Event” on page 77.
A15.Breakaway Hydrostatic Relief Valve
In normal operation, this valve never activates. It is
designed to open at 375 psi, well above the
250-265 psi operating pressure of the nurse tank’s
main pressure 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 page 116). See
“Hydrostatic Relief Valve Maintenance” on
page 114 for maintenance.
Valve function: when operating valves are closed on
both sides of the breakaway (or on just the
applicator side upon a breakaway event), NH
3
can
be trapped in the breakaway coupler. As the NH
3
warms, it could create dangerously high pressure.
This relief valve opens to vent excess pressure.
Suffocation, Blinding and Burning Hazards:
See “Safing Applicator Before Cart Hitch” on page 67,
for safe opening procedure.
a. Acme refers to the ANSI/ASME B1.5-1997 screw thread, which has a trapezoidal thread profile.
Suffocation, Blinding and Burning Hazards:
See “About Bleed Valves:” on page 32.
A11 A24
A49
A57
Upon Event: Probable Chemical Hazard:
See “Breakaway Event” on page 77.