WSP™
DATA SHEET
WSP™ SELF-PRIMER PUMPS
WSP-D300_6
Rev. 3
01/09/20
© 2019 The Factory
47
3. Bypass Lines
When priming, air from the suction line
must
be vented on the
discharge side to the outside since self-priming pumps are
not
air
compressors. Should the discharge line be open, this air will vent
through the discharge.
When a discharge line check valve is installed, the pump discharge
side
must be
open to outside pressure. The discharge may either be
through a bypass line or through a WSP™ ARV that has been
installed between the pump discharge and the check valves.
Self-priming centrifugal pumps cannot prime when there is enough
interior liquid pressing against the discharge check valve to keep it
closed.
NOTE:
Any bypass line must be correctly sized to avoid compromising the pump’s
discharge capacity. A bypass line must have a minimum diameter of 1 inch
to reduce chances of plugging.
During low discharge head applications under 30-feet or 9-meters, Weir
Specialty Pumps advises a bypass line running back to the wet-well. Place
the bypass line at the cut-off point of the low-level pump or 6 inches below
the level of the water.
Occasionally, installations of the bypass line will end with a 6 to 8 foot length
of 1½-inch I.D.
smooth-bore
hose. In these cases, any air and liquid that is
vented during priming will vibrate the hose, breaking up remaining solids,
grease or other materials residing in the line. This reduces clogging.
BYPASS LINES MUST BE SECURED AGAINST BEING DRAWN INTO THE PUMP
SUCTION INLET WHEN RETURNED TO A WET WELL.
Weir Specialty Pumps advises the installation of pipe unions in a bypass line
at every 90º elbow to facilitate disassembling the parts for maintenance and
repair.
If the pump is used on high discharge head applications extending more than
30 feet under full working pressure, a larger volume of liquid may be
bypassed back to the wet-well. Such an occurrence will reduce the pumps
performance. To avoid this, Weir Specialty Pumps advises installing a
WSP™ ARV (WSP™ Automatic Air Release Valve) in the bypass line.
Summary of Contents for WSP-6
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