
NP2540
Maintenance and Lubrication
119
2019-04-12
417-459M
Clearing Plugged Application Tubes
A plugged application tube
often results in the delivery tubing
lifting off the 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 28).
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 28).
Clearing Open Line Application Plugs
1. Stop operation (page 68).
2. Discharge the system (page 116).
3. If the 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 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 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 68).
3. Discharge the system (page 116).
The standard
discharge is not likely to adequately discharge any
plugged or closed 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 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 tine tubing.
6. Use a thin flexible tool (a coat hanger may suffice) to
clear the 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 tine tube about
3
/
4
inch (19 mm). Slide the spring clamp to centered
in the overlap.
a. PPE: Personal Protective Equipment
1
2
2