Suspended Wet-Pit Sewage Pumps
Bulletin 228E

BASIN & PITS

Drawings show standard arrangements of simplex and duplex VSP units. Square steel covers are for concrete pits and are usually furnished with grouting frames. Round steel covers are for cast iron, steel and fiberglass basins. When round covers are for concrete pits, they are usually furnished with grouting frames. Covers have a corrosion resistant coating. Non-standard shapes and arrangements are available.

Type PF-1 furnished as standard for square and rectangular pits. Permits frame and cover to be installed flush with finished floor. Has bar support for cover.

Type PF-2 construction same as PF-1 except with angle iron support for cover.

Type PF-3 furnished as standard for round pits. Frame supports cover and should be recessed into concrete so that cover is flush with finished floor.

Type PF-4 construction same as PF-3 except with filler strip. Frames and covers are treated with corrosion resistant coating, and are available in non-standard shapes and sizes, sectional construction, and galvanized or checkered steel.

DIMENSIONS
Dimensions are subject to change and should not be used for construction purposes unless certified. All dimensions are in inches unless otherwise noted.

SIMPLEX AND DUPLEX UNITS
While the dimension drawing on this page shows a duplex unit in a basin, the data on the drawing applies to simplex and duplex units.

INLETS
Basins can be furnished with any number of inlets, of the styles shown on this page, in sizes 2" thru 8". The inlet depth is determined by job conditions such as distance from farthest fixture and pipe pitch. Indicate size, style and depth of inlet in the boxes provided on the drawing, when releasing the basin for fabrication. Unless otherwise requested, the inlet centerline is directly below the centerline of the manhole.

COVERS
All basin covers are steel. Covers for cast iron and fiberglass basins are bolted onto the top flange of the basin. Covers for steel basins are welded onto the basin shell and, therefore, there is no top flange. Basin covers have required openings for pumps and controls plus a vent connection and a manhole (with a cast iron manhole cover).

The standard vent connection for a sump pit or basin cover is a 2" screwed connection. If local code requires a larger vent connection, it must be so specified when the unit is ordered.

Covers are furnished with bolts and gasketing for gastite field assembly on the basin. Pumps are furnished with bolts and gasketing for gastite field assembly on the cover.

SECTIONAL BASINS
Standard steel and fiberglass basins are built in one section. Mufti-section basins are furnished only when specified.

Standard cast iron basins are built in one, two, three or more sections, depending on the basin depth. The intermediate flanges of multi-section basins have the same outside diameter and bolt hole dimensions as the top flange on which the cover is mounted. Bolts and gasketing are furnished for field assembly of the sections.

SQUARE BASINS
Square and rectangular basins are available in steel construction only. Cast iron and fiberglass basins are not available in these shapes.

SIZING THE BASIN
In most cases, the basin diameter can be the minimum shown in the table on this page, and the depth should be sufficient to allow three feet below the inlet connection. If job conditions require shallower basin, increase the diameter. The pumping cycle can be determined from the volume of water between the inlet connection and a line one foot above the bottom of the basin.

CONCRETE PITS
VSP pumps can be furnished with cover plates and grouting frames for concrete sump pits. Pit frame types and standard simplex and duplex cover layouts are shown on VSP main page.

STEEL BASINS
VSP sump pumps can be furnished with basins of heavy welded steel construction. The dimension drawing and inlet connections drawing on this page also apply to steel basins, except for the 'A' dimension (top basin flange).

PUMP AND BASIN SIZING

PUMP CAPACITY:
Type VSA sewage pumps are used to handle sewage and other liquids containing solids where gravity drainage is not practical.

Single pump units may be used but duplex units are recommended so that, in the event of failure of one pump, the second pump is available to handle the in-flow. Duplex units are required by the National Plumbing Code when more than six water closets are handled.

Each pump of a duplex set is sized to handle the full pump capacity. Pump capacity can be determined by the number of water closets to be handled. The capacities shown below apply to single pumps and to each pump of a duplex set.

Fixtures other than water closets need not be considered when using the above table. However, if outside drainage (see below) is greater than half the pump capacity shown above, add the excess amount of outside drainage to the pump capacity.

OUTSIDE DRAINAGE:
Paved Area:  10 g.p.m. per 1,000 sq. ft. of area. Tile Drainage Bed (Sandy Soil) 15 g.p.m. per 1,000 sq. ft. of bed.
Tile Drainage Bed (Clay Soil):   8 g.p.m. per 1,000 sq. ft. of bed.

UNUSUAL EXTRA IN-FLOW FACTORS:
If drainage is to be handled by the sewage pumps from unusual sources such as boiler blow-down, air conditioning condensate, pools. display fountains. wash racks, etc.. add this additional in-flow to the pump capacity.

PUMP DISCHARGE HEAD:
The pump discharge head includes the following three elements:

- Static Head:  The difference in elevation between the lowest water level in the basin (generally 1 ft. above the bottom of the basin) and the maximum height of the discharge line.
- Friction:  Loss of head in the discharge line from friction through pipe, valves and other fittings.
- Back Pressure:  In cases where the run-off sewer is charged, add for the sewer back pressure (generally from 2 ft to 8 ft.)

Example: 
Sewage basin is 5 ft. deep and set in ground with top flush with finished floor of basement. Basement floor is 10 ft. below highest point of pump discharge line. Pump capacity is 100 g.p.m. Size of discharge line is 4"

Static head   ---   14 ft.
Friction loss thru discharge pipe   ---   2 ft.
Friction loss thru discharge valves & fittings   ---   3 ft. 
Back pressure in charged sewer   ---   4 ft.

Total pump discharge head 23 ft. 

PIT OR BASIN SIZE
For most installations, pit or basin diameters (or squares) can be the minimums shown in the table on the back page of this bulletin. In some cases, the minimum basin diameters shown can be reduced if space conditions require (consult ABC Electric Corp.).

Pit or basin depth should be sufficient to allow 3 ft. below the inlet connection. The pump tum-on level is just below the inlet connection and the pump turn-off level is 1 ft. above the bottom of the basin. Therefore, each pump cycle will pump 2 ft. of water.

If job conditions require basins to be shallower than recommended, increase the basin diameter.

Capacities (in gallons) of round pits and basins per foot of depth are shown in the dimension table above. To determine the capacity (in gallons) of a square or rectangular pit, multiply the cubic feet by 7.5.