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Submersible Pumps:
History
Courtesy of: Zoeller Engineered
Products
Originally used in Europe, submersible wastewater pumps were first
seen in the U.S. Market in the mid-1950s. They became popular in the early 1960s
when a guide rail system was developed to lift pumps out of well pits for easy
maintenance and repair. This ended the dirty and sometimes dangerous task of
sending people into the sewage or wet pit.
Submersibles are now the dominant pump in the municipal lift station market.
They are used primarily for wet-pit sewage lift stations and for industrial sump
or process effluent applications. Submersibles offer these advantages:
- low initial cost since they involve only one pit and less auxiliary
equipment is required than for dry well/wet well installations;
- low operating costs;
- safe and quiet installations;
- a minimum of unsightly above-ground equipment; and, above all,
- reliable operation over a long life.
A submersible lift station includes not only the pump-motor unit, but
sophisticated electrical and mechanical controls, piping and a wet well with an
access frame and cover.
Submersible pumps are also widely used to handle suspended solids effectively
and efficiently.
SWPA's members manufacture submersibles that handle 2-1/4-inch and larger
solids and have a minimum 3-inch discharge. It is estimated that SWPA's member
pump companies manufacture and sell more than 75% of these pumps in the United
States.
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Information Needed to Properly Select a Pump
You mostly need to know 5 items as follows:
1) VOLTAGE
2) WHAT IS BEING PUMPED?
3) HOW HIGH DO YOU HAVE TO PUMP VERTICALLY?
4) HOW FAR DO YOU HAVE TO PUMP HORIZONTALLY?
5) TYPE OF PIPE AND SIZE.
SIZING A SEWAGE PUMP:
There are actually 3 ways to size a sewage pump. Each method will provide an estimate of peak flow conditions.
1) FIXTURE UNIT CALCULATION
This method
uses the "Hunter Curves" for approximating water usage by a typical
plumbing fixture. This is an acceptable way of estimating the pump flow
requirement for residential and small commercial applications.
2) LARGER CAPACITY SYSTEM CHART
This is a
derivation of the fixture unit method. It takes into consideration that
in a high density environment, a ratio of plumbing fixture use can be
applied to approximate peak flows. Method can be utilized for
structures such as motels, apartment complexes, trailer parks, large
office buildings and etc.
3) POPULATION METHOD
Method of
calculating demand used by civil engineers when designing municipal
sewage systems. A gallon per day usage pattern is established for each
type of building structure. Then a peak factor is applied which is
spread out over a 24 hour period. This method is used for homes and
other residences whose sewage flows into a municipal sewage system.
This method can only be used in those applications where a large basin
is used.
Regardless of what
your peak flow requirement is for a given application, the pump must
always be able to provide a minimum velocity of 2 feet per second
through the line. Line sizes with their accompanied minimum flow rates
are as follows:
1.25" - 9 GPM 3" - 46 GPM
1.5" - 13 GPM 4" - 78 GPM
2" - 21 GPM 6" - 180 GPM
4) OTHER FACTORS CONCERNING PUMP SELECTION:
1) Total
dynamic head (tdh) in feet is the total resistance in the piping
network which you are pumping against. Do not select a pump if the tdh
is less than the minimum point shown on its’ curve.
2) the pump selected must be capable of pumping to the highest vertical point in the system.
3)
do not undersize the basin. If possible, always select a pump and basin
assembly which will allow for at least a 30 second pump cycle.
4)
air can interfere with the pump’s ability to work. Always drill a
vent hole in the discharge line between the pump and check valve. In
long horizontal runs of pipe, air relief valves may be required.
We honor ALL our Manufacturers' warranties:
for further details, please contact us, or visit any of the manufacturers as listed under Products page
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Submersible Pumps:
Overview
Ejector pumps are required in those applications where
wastewater can not flow to it’s point of destination by means of
gravity at a velocity rate greater than 2 feet per second.
DESIGN STYLES:
1) vertical suspended type— motor is exposed outside of basin
supported on the cover with an extended motor shaft connected to the
pump housing and impeller which are located inside the basin.
2) close coupled submersibles— motor is connected directly to the
pump housing and impeller with a short shaft and no part of the pump is
exposed outside the basin.
These styles are available with either an explosion proof or
non-explosion proof motor...often, an explosion proof motor is not
practical but sometimes required by code.
MAJOR TYPES:
1) NON-CLOGS have the ability to pump high gpm’s ...
Solids handling capacity from 2" thru 4"...
Lower head residential to municipal lift stations …
Pumping everything from sanitary sewage to rainwater to a gravity sewer system...
2) GRINDERS pumps low flows against high heads...
Grinds solids instead of passing them...
Residential or commercial location...
Often pumping to a pressure sewer system but also used in gravity
sewers if high vertical lifts or long horizontal runs are present in
system...
3) EFFLUENT PUMP pump used to move septic tank effluent...
High head low flow pumping performance...
1/2" - 3/4" solids capacity...
Used in septic tank systems to move effluent from the dosing chamber to either an on site treatment system or pressure sewer...
4) SUMP PUMP pump used for moving groundwater away from building foundations...
Low flows against low heads...
Minimal solids capacity...
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