Great Plains NP4000B Operator Manual - Manual (Page 26)

22 2013+ NP4000/A/B Table of Contents Index Great Plains Manufacturing, Inc.
417-199M Table of Contents Index 2014-05-14
NH
3
System Narrative
This list describes a single-cooler anhydrous system with
section control. A dual-cooler system has two of
components
through , and two additional
dual-tube tines . A single-section system lacks
components through and has only one of .
Refer to Figure 6 on page 29
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 64 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 “NH3: Making Nurse Tank
Connections” on page 64, “NH3: Unhitching
Nurse Tank” on page 73 and “NH3: Breakaway
Event” on page 71.
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 does not happen.
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 “NH3: Breakaway
Event” on page 71.
A15.Breakaway Hydrostatic Relief Valve
In normal operation, this valve does not activate.
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 124). See “Hydrostatic Relief Valve
Maintenance” on page 122 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.
Legend:
Liquid NH
3
Liquid Flow
NH
3
Vapor Vapor Flow
Direction of Flow Exception Flow
A11 A24
A49
A35 A39 A40
Suffocation, Blinding and Burning Hazards:
See “NH3: Safing Applicator Before Cart Hitch” on
page 61, 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 38.
A57
Upon Event: Probable Chemical Hazard:
See “NH3: Breakaway Event” on page 71.