7
English
(US)
Fig. 4
Air pocket prevention
4.10 Discharge (outlet) piping
• Short discharge piping can be the same diameter as the pump
discharge opening. Longer piping should be one or two sizes
larger depending on length.
• An even gradient is best for long horizontal runs of discharge
piping.
• Install a valve near the discharge opening to prime and start
the pump. The discharge gate valve is also used to isolate the
pump during shutdown, maintenance, and facilitate pump
removal.
• Any high points in discharge piping may entrap air or gas and
thus retard pump operation.
• If the possibility of liquid hammer exists, (i.e. check valves are
used) close the discharge gate valve before pump shutdown.
4.11 Shaft sealing-general comments
• PACO offers both mechanical seals and packed stuffing boxes
as a means to seal the shaft. Pumps with stuffing boxes are
normally packed before shipment. If the pump is installed
within 60 days after shipment, the packing material will be in
good condition for operation with a sufficient supply of
lubrication. If the pump is stored for a longer period, it may be
necessary to repack the stuffing boxes.
• The stuffing box must be supplied at all times with a source of
clean, clear liquid to flush and lubricate the packing. When
pumps are equipped with mechanical seals, no maintenance
or adjustment is required. Mechanical seals are preferred to
packing on most applications because they require less
maintenance.
4.12 Packing gland adjustment
With the pump running, the packing gland should be adjusted to
permit 40 to 60 drops per minute leakage. This is required for
shaft lubrication. After initial start up, additional packing and
adjustment may be required. Pumps with mechanical seals
require no adjustment.
4.13 Mechanical seals
All PACO Type L pumps that are equipped with mechanical seals
are matched to conditions for which the pump was sold. Observe
the following precautions to avoid seal damage and obtain
maximum seal life:
• Do not exceed temperature or pressure limitations for the
mechanical seal used.
• DO NOT RUN THE PUMP DRY OR AGAINST A CLOSED
VALVE! Dry operation will cause seal failure within minutes.
• Clean and purge suction piping in new installations before
installing and operating pump. Pipe scale, welding slag and
other abrasives can cause rapid seal failure.
Fig. 5
Checking parallel alignment
Fig. 6
Checking alignment
TM
05
47
92
26
13
TM
05
47
95
26
13
TM
05
479
4
2613
PA
CO Pumps
10
