Great Plains NP30A 30-foot Operator Manual - Manual (Page 116)

112 NP30A or NP40A Table of Contents Index Great Plains Manufacturing, Inc.
407-502M Table of Contents Index 2014-05-20
Clearing Plugged Knives or Tines
Knives or tines can get plugged at release ports , due
to sticky soil, reverse movement and other causes.
Routinely check knives or tines for evidence of plugging
just prior to nurse tank hitching. More rarely, unusual field
debris can cause a tubing disconnect at a knife or tine.
Treat it as a plugged line until you confirm otherwise.
Elevated Ammonia Exposure Hazard:
Follow clearing instructions carefully. Wear your PPE
a
.
Plugged delivery lines with tubing still attached can have
significantly greater than normal NH
3
liquid which is not
likely to be mitigated by the normal Discharge procedures.
Hastily disconnecting a charged line will release a dangerous
amount of NH
3
liquid and vapor. Your PPE is not designed to
protect you against such a release. Burning, respiratory injury,
blinding or death could result.
Refer to Figure 88
Clearing Plugged Application Tubes
A plugged application tube often results in the delivery
tubing lifting off the knife or tine tubing at the clamp
(an “open line plug”). The disconnect is usually easy to
spot in the field as a condensation cloud from the row.
The row is likely to be taking more than its equal share of
NH
3
from the flow divider. You may see a drop in
pressure at the flow divider gauge ( on page 21).
If the plugged line remains closed (“closed line plug”),
the tubing may be completely full of liquid NH
3
by the
time you detect the problem. You may notice an increase
in pressure at the flow divider gauge
, or pressure
pulses, as trapped liquid warms, periodically vaporizes,
and blows back into the flow divider (
on page 21).
Clearing Open Line Application Plugs
1.
Stop operation (page 76).
2. Discharge the system (page 110).
3. If the knife or tine tubing is cold, wait for it to warm to
ambient temperature (and vaporize any liquid NH
3
inside).
4. Use a thin flexible tool (a coat hanger wire may
suffice) to clear the knife or tine tube from above or
below.
5. Reconnect the application tubing. Squeeze the
spring clamp
. Slide it up the delivery tubing. Push
the delivery tubing onto the knife or tine tube about
3 ⁄
4
inch (19 mm). Slide the spring clamp to centered
in the overlap.
Clearing Closed Line Application Plugs
1.
Review the WARNING at the top of this page.
2. Stop operation (page 76).
3. Discharge the system (page 110). The standard
discharge is not likely to adequately discharge any
plugged, closed, delivery lines. Expect continuing
vapor release at non-plugged rows. The plugged line
discharges back through the flow divider, and out the
other rows.
4. Wait until the plugged knife or tine has warmed to
ambient temperature, and the liquid level in the
plugged loop is about the same as in the open loops.
5. Squeeze the spring clamp . Slide it up the tubing.
Pull the delivery tubing off the knife or tine tubing.
6. Use a thin flexible tool (a coat hanger may suffice) to
clear the knife or tine tube from above or below.
7. Reconnect the application tubing. Squeeze the
spring clamp. Slide it up the delivery tubing. Push the
delivery tubing onto the knife or tine tube about
3 ⁄
4
inch (19 mm). Slide the spring clamp to centered
in the overlap.
a. PPE: Personal Protective Equipment
A45
Figure 88
Dual Knife Vapor Tube
31634
1
2
1
1
A45
A42
A42
A40
2
2