Submittal Sheet

Pump and system sizing instructions
Unilift CC, KP, AP
7
60
3. Size of solids
If the building has a water closet of any kind, it will
pass 2" solids and require a sewage pump. If it does
not have a water closet, it will only need to pass at
least 0.75" or smaller solids, and will require an
effluent pump.
4. Pump selection
Proceed as follows:
1. Go back to steps 1, 2 and 3 and find this
information:
• capacity (GPM)
• total dynamic head required
• solids handling requirements.
2. refer to the pump performance curves
3. find the best pump for the application
4. select the smallest pump that meets the capacity
and head requirements and can pass the required
solids size. (See performance curves in this product
guide).
5. Basin size
To determine the proper basin size, refer to the
required capacity of the system. Convert this to the
volume the pump must be able to pump out of the
basin during each cycle ("pumpable volume", see
figure below) using this formula:
GPM x run time = volume
The run time must be at least two minutes to ensure
against short cycling (which would greatly reduce the
service life of the pump). Therefore, if the flow rate is
50 GPM, the pumpable volume required in the basin
must be 100 gallons.
Referring to the figure below and the table on the
following page, select a basin diameter and float
switch free cable length that will guarantee a sufficient
pumpable volume. Make sure that these requirements
are fulfilled:
• The basin must be deep and wide enough to allow
space for the ON/OFF range of the float switch to
move freely.
• The bottom of the basin inlet must be at least 24"
above the bottom of the basin.
• See descriptions of the individual pumps for water
level required above the pump (submergence).
Fig. 56 Schematic drawing of ejector basin with pump,
piping and float switch
Approximate pumpable volume (in gallons) for various
combinations of basin diameter and float switch free
cable lengths.
The values are approximate only. Volume may differ
slightly due to basin construction.
GPM x Run time [mins.] = Volume [gals]
50 x 2 = 100
TM 043426 4408
Free cable length of float switch
[inches]
OFF 3.5 6 8 10 12 14 16 18 20 22 24
ON 5.5 10 12 16 18 22 25 28 30 32 36
Basin
diameter
Approximate pumpable volume
[gallons]
18" 6 11 13 17 20
24" 11 20 23 29 35 41 47
30" 17 31 37 46 55 64 73
36" 24 44 53 66 79 93 106 123 132 145 159
48" 43 78 94 117 141 164 188 219 235 258 282
60" 67 122 147 184 220 257 294 343 367 04 440
72" 97 176 211 264 317 370 423 493 529 581 634