EBARA EFQT3 - Manual (Page 8)

EBARA Fluid Handling 8
If hose is used in suction lines, it must be the
rigid-wall, reinforced type to prevent collapse
under suction. Using piping couplings in
suction lines is not recommended.
Line Configuration
Keep suction and discharge lines as straight
as possible to minimize friction losses. Make
minimum use of elbows and fittings, which
substantially increase friction loss. If elbows
are necessary, use the long radius type to
minimize friction loss.
Connections to Pump
Before tightening a connecting flange, align
it exactly with the pump port. Never pull a
pipe line into place by tightening the flange
bolts and/or couplings.
Lines near the pump must be independently
supported to avoid strain on the pump which
could cause excessive vibration, decrease
bearing life, and increased shaft and seal
wear. If hose-type lines are used, they
should have adequate support to secure
them when filled with liquid and under
pressure.
Gauges
Most pumps are drilled and tapped for
installing discharge pressure and vacuum
suction gauges. If these gauges are desired
for pumps that are not tapped, drill and tap
the suction and discharge lines not less than
18 inches (457,2mm) from the suction and
discharge ports and install the lines.
Installation closer to the pump may result in
erratic readings.
SUCTION LINES
To avoid air pockets which could affect
pump priming, the suction line must be as
short and direct as possible. When operation
involves a suction lift, the line must always
slope upward to the pump from the source of
the liquid being pumped: if the line slopes
down to the pump at any point along the
suction run, air pockets will be created.
Fittings
Suction lines should be the same size as the
pump inlet. If reducers are used in suction
lines, they should be the eccentric type, and
should be installed with the flat part of the
reducers uppermost to avoid creating air
pockets. Valves are not normally used in
suction lines, but if a valve is used, install it
with the horizontal to avoid air pockets.
Strainers
If a strainer is furnished with the pump, be
certain to use it; any spherical solids which
pass through a strainer furnished with the
pump will also pass through the pump itself.
If a strainer is not furnished with the pump,
but is installed by the pump user, make
certain that the total area of the openings in
the strainer is at least three or four times the
cross section of the suction line, and that the
openings will not permit passage of solids
larger than the solids handling capability of
the pump.
This pump is designed to handle up to 2 ½
inch (63.5 mm) diameter spherical solids.
Sealing
Since even a slight leak will affect priming,
head, and capacity, especially when
operating with a high suction lift; all
connections in the suction line should be
sealed with pipe dope to ensure an airtight
seal. Follow the sealant manufacturer’s
recommendations when selecting and
applying the pipe dope. The pipe dope
should be compatible with the liquid being
pumped.
Suction Lines in Sumps
If a single suction line is installed in a sump,
it should be positioned away from the wall of
the sump at a distance equal to 1 ½ times
the diameter of the suction line.
If there is a liquid flow from an open pipe into
the sump, the flow should be kept away from
the suction inlet because the inflow will carry
air down into the sump, and air entering the
suction line will reduce pump efficiency.