Technical Booklet N Drainage·Page 13·Table 2.4
Common branch discharge pipes (unvented)
Table specifying maximum number of appliances, maximum branch length, minimum pipe sizes, and gradient limits for unvented discharge pipes serving water closets, urinals, and washbasins.
Common branch discharge pipes (unvented)
Appliance | Max number to be connected | Max length of branch (m) | Min size of pipe (mm) | Gradient limits (fall per metre) min (mm) | max (mm)
WCs | 8 | 15 | 100 | 9(2) | 90
Urinals: Bowls | 5 | –(1) | 50 | 18 | 90
Urinals: Stalls | 6 | –(1) | 65 | 18 | 90
Washbasins | 4 | 4 (no bends) | 50 | 18 | 45
Notes:
(1) No limitations as regards venting but should be as short as possible.
(2) Minimum gradient should be not less than 18 mm if only 1 WC is connected.
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