EBARA EFQT8 - Manual (Page 8)

EBARA Fluid Handling 7
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 3 inch (76 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.