Draining Systems - Main Vents
Vents in draining systems protects traps against pressure differences that could cause them to siphon or blow out .
Vents protects traps against pressure differences that could cause them to siphon or blow out, leaving occupants unprotected against smell and potential contaminants from the sewer system.
| Pipe Size (in) | Max. Drainage Fixture Units (DFU) |
|---|---|
| 1 1/4 | 1 |
| 1 /1/2 | 81) |
| 2 | 24 |
| 2 1/2 | 48 |
| 3 | 84 |
| 4 | 256 |
1) No water closets permitted
- at least one vent should terminate through the roof
- air admittance valves within the building may be permitted (check local authority)
- terminating vents in side wall may be permitted (check local authority)
