Xylem Wastewater (Technical Manual) - Manual (Page 9)

PAGE 9
Wastewater
Goulds Water Technology, Bell & Gossett,
Red Jacket Water Products, CentriPro
Example: Fig. 1. A two-bathroom home is situated such that
the city sewer main is located above the basement drain facili-
ties. Groundwater seepage through drain tile into the sump is
estimated at 6 GPM. The vertical distance from the pump to the
highest point in the discharge piping is 12 feet.
A pump capable of pumping 30 GPM is required (seepage is
less than one-fourth of the pump capacity so it is automatically
included). The discharge head must be 12 feet, plus any friction
loss in the approximately 15 feet of pipe, 3-90º elbows, 3-45º
elbows, and check valve.
Assume plastic pipe is used.
1. RATE OF FLOW = 30 GPM
Two (2) toilets, includes seepage up to one-fourth of
selected ____ pump capacity. 6 GPM is less than the
7.5 GPM allowable so no correction is necessary.
2. SUCTION CONDITIONS – Flooded Suction
3. DISCHARGE CONDITIONS
Vertical Differential 12.0'
Friction losses @ 30 GPM
15' of 2" pipe (1.8' per 100' of pipe) = .2' F.L.
3-2", 90º elbows = 16.5 equivalent feet
3-2", 45º elbows = 7.5 equivalent feet
1-check valve = 19.0 equivalent feet
Total = 43.0 equivalent feet = .6' F.L.
Total Discharge Head = ___________________ 12.8'
Referring to the catalog, we find that a
1 /
3
HP Sewage Pump
should be adequate for the job.
Example: The same conditions as in the previous example exist,
except the house is located on a large tract of sandy soil where
the groundwater seepage is estimated @ 20 GPM.
1. RATE OF FLOW = 30 GPM
Two (2) toilets, includes seepage up to one-fourth of
selected pump capacity – 7.5 GPM.
The additional 12.5 GPM (20-7.5) must be added to
the required pump capacity – 12.5 GPM
Total = 42.5 GPM
2. SUCTION CONDITIONS ____________Flooded Suction
3. DISCHARGE CONDITIONS
Vertical Differential – 12.0'
Friction losses @ 42.5 GPM
15' of 2" pipe (3.5' per 100' of pipe) = .5' F.L.
3-2", 90º elbows = 16.5 equivalent feet
3-2", 45º elbows = 7.5 equivalent feet
1-check valve = 19.0 equivalent feet
Total = 43.0 equivalent feet or 1.5' F.L.
Total Discharge Head = 14.0'
Referring again to the catalog, we find that a
1 /
3
HP
Sewage Pump should be adequate for this installation.
Head Calculation
Flow Calculation Example
To Calculate Flow with Fixture Counts
Take total number of each style fixture X Count for that fixture.
Add all fixture total counts. Add Full Body shower flow rate to
total.
Use “Hunter” estimate curves for Demand Load for appropriate
style fixtures. (Valve style fixtures are predominant in Commercial
buildings; Tank style fixtures are predominant in Residential).
COMMERCIAL BUILDING EXAMPLE:
Valve Style Fixtures
25 Toilets
25 Lav sinks
25 Tubs
6 Kitchen Sinks
2 Commercial Washing Machines
1 Dishwasher
Count Calculation
25 Toilets
X 10 Count = 250
25 Lav Sinks X 3 Count = 75
25 Tubs X 4 Count = 100
6 Kitchen Sinks X 4 Count = 24
2 Commercial X 6 Count = 12
1 Dishwasher X 4 Count = 4
Total 465 Count
Plumbing Water Systems
Fixture Units
“Hunter” Estimate Curves for Demand Load
Demand GPM
1
2
0 500 1000 1500 2000 2500 3500
100
500
200
300
400
1 – For system predominantly for flush valves
2 – For system predominantly for flush tanks 120
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