Great Plains NP3000A Operator Manual - Manual (Page 115)

Great Plains Manufacturing, Inc. Table of Contents Index Maintenance and Lubrication 111
2014-04-22 Table of Contents Index 407-613M
Clearing Plugged Vapor Tubes
Elevated Ammonia Exposure Hazard:
Follow clearing instructions carefully. Wear your PPE
a .
Plugged vapor tubes still attached can contain significantly
greater than normal NH
3
vapor, which is not likely to be
mitigated by normal Discharge procedures. Disconnecting a
charged line releases a dangerous amount of NH
3
vapor. PPE
is not designed to protect against such a release. Burning,
respiratory injury, blinding or death could result.
Refer to Figure 70
A plugged vapor tube
often usually does not result
in the vapor tubing lifting off the tine tubing at the clamp
(it is a “closed line plug”).
If only one vapor line is plugged, the symptom may be an
elevated temperature at the cooler gauge (
on
page 29), and possibly a rate alarm if cooling is
insufficient. If both vapor lines at a cooler are plugged
(at moderate or warm ambient temperatures) the
temperature gauge rises higher, and more quickly.
Cooling ceases. Cooler pressure rises. Flow divider
pressure falls. Rate alarm is likely. Normal Discharge
may not clear the line.
If the plugged line disconnects (“open line plug”), you
may see little change from normal operations. Odor is
elevated, if you drive down-wind of application. The
vapor line may not cause a cloud. The change in cooler
pressure may be minor. You are most likely to detect an
open line plugging of a vapor line during routine row
inspection at re-hitch.
Clearing Closed Line Vapor Plugs
1.
Review the WARNING at the top of this page.
2. Stop operation (page 64).
3. Discharge the system (page 108). The standard
discharge is not likely to adequately discharge any
plugged, closed, vapor lines. Expect continuing
vapor release at non-plugged rows. The plugged line
discharges back through the cooler, then through the
flow divider and out the other rows.
4. Wait until the plugged tine has warmed to ambient
temperature, and there is no liquid in the vapor line.
5. Loosen the screw clamp . Slide it up the vapor
tubing. Pull the vapor tubing off the tine tubing.
6. Use a thin flexible tool (a coat hanger wire may
suffice) to clear the tine tube from above or below.
7. Reconnect the vapor tubing. Push the vapor tubing
onto the tine tube about
3 ⁄
4
inch (19 mm). Slide the
screw clamp to centered in the overlap and secure.
Clearing Open Line Vapor Plugs
1.
Stop operation (page 64).
2. Discharge the system (page 108).
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 may suffice) to
clear the tine tube from above or below.
5. Reconnect the vapor tubing. Push the vapor tubing
onto the tine tube about
3 ⁄
4
inch (19 mm). Slide the
screw clamp to centered in the overlap and secure.
a. PPE: Personal Protective Equipment
Figure 70
Dual Tine Vapor Tube
34990
1
3
A45
A48
A27
3