Waste Water Piping - Flow Capacities vs. Dimensions
In sewage piping and pumping systems the flow velocity must exceed certain limits to maintain trouble free operation and to avoid settling and sedimentation of solids:
- for horizontal wastewater pipe systems with solids the speed should exceed 3 ft/sec
- for wastewater water system with organic solids the speed should exceed 2 ft/sec
On the other hand, the flow velocity should not exceed certain limits to avoid potential wear and tear due to erosion and abrasion:
- the flow velocity in high-grit sewage handling systems should not exceed 12 ft/sec
- the flow velocity in sewage systems with low grit concentrations should not exceed 18 ft/sec
Flow rate capacities in US gal for sewage piping and pumping systems within the limitations:
| Pipe Dimension (inches) | Flow Rate (US GPM) | |||
|---|---|---|---|---|
| Minimum Velocity | Maximum Velocity | |||
| 2 ft/sec (0.6 m/s) | 3 ft/sec (0.9 m/s) | 12 ft/sec (3.6 m/s) | 18 ft/sec (5.4 m/s) | |
| 3 | 45 | 65 | 270 | 400 |
| 4 | 80 | 120 | 480 | 700 |
| 6 | 180 | 260 | 1050 | 1600 |
| 8 | 300 | 500 | 1900 | 2800 |
| 10 | 500 | 750 | 3000 | 4400 |
| 12 | 700 | 1100 | 4300 | 6400 |
Note! - based on clean pipes. The friction coefficient may vary with the pipe material.
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