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.

Pump and Basin Sizing

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 1000 sq. ft. of bed.

Tile Drainage Bed (Clay Soil) 8 g.p.m per 1000 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. In some cases, the minimum basin diameters shown can be reduced if space conditions require (consult the factory).

Pit or basin depth should be sufficient to allow 3 ft. below the inlet connection. The pump turn-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. To determine the capacity (in gallons) of a square or rectangular pit, multiply the cubic feet by 7.5.

Pump CONTROLS

The following control arrangements are available:

FS-1 (for single unit) - one float switch for start-stop control.

FS-2 (for duplex unit) - two float switches for start-stop control. The switches can be manually set to change the lead pump. Both pumps will operate if the in-flow rate requires.

FS-3 (for duplex unit) - one altemating float switch which operates the two pumps on an alternating basis and turns on both pumps simultaneously if the in-flow rate requires.

FS-4 (for duplex unit) - one altemating float switch (as described immediately above) plus two-pole emergency auxiliary float switch which will tum on both pumps at a predetermined high water level if the alternating float switch fails to operate for some reason.

FS-5 (for single or duplex unit) - a compression tube type high water alarm actuating switch with integral alarm horn. Can also provide signal for remote alarm indication. Alarm panel with bell, indicating light and silencing button is also available.

FS-6 (for single or duplex unit) - one float switch to act as a high water alarm actuator instead of the compression tube type described immediately above.

The following control arrangements are available:

For single or duplex units: (1) magnetic starter for each motor to be mounted on an adjacent wall or on the float switch pedestal(s).

For duplex units: A Type D Duplex Control Panel in a single enclosure for mounting on an adjacent wall. These panels are available as follows:

D1000: (2) magnetic starters in one enclosure.

D1100: (2) magnetic starters and (2) unfused disconnect switches in one enclosure.

D1200: (2) magnetic starters and (2) fusible disconnect switches in one enclosure.

D1300: (2) magnetic starters and (2) circuit breakers in one enclosure.

Modifications are available for magnetic starters and Type D Duplex Panels as follows: special enclosures, 'Hand-off-Automatic' selector switches, pilot lights, control circuit transformers, manual transfer switch and automatic pump alternator.

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 inches thru 8 inches. The inlet depth is determined by job conditions such as distance from farthest fixture and pipe pitch. Indicate size, style and depth of inlet 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 cast iron manhole cover).

The standard vent for a sewage pit or basin cover is a 3 inch screwed connection. If local code requires a 4 inch 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. Multisection 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 multisection 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.