Siphonic drainage

Points to consider for gravity configuration Conventional roof drains have no recognized test data available at this time. [...]ponding levels are therefore difficult to determine at design flow rate; Pipework from the roof drains drops directly down a stack to large, low-level collection pipes, ins...

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Bibliographic Details
Published in:PM Engineer 2020-06, Vol.26 (6), p.44-46
Main Author: McNicol, John
Format: Article
Language:English
Subjects:
Backfill
Configurations
Design
Drainage
Drains
Flow velocity
Hydraulics
Minimum flow
Pipe cleaning
Pipework
Rain
Roofs
Software packages
Software upgrading
Storm sewers
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Summary:Points to consider for gravity configuration Conventional roof drains have no recognized test data available at this time. [...]ponding levels are therefore difficult to determine at design flow rate; Pipework from the roof drains drops directly down a stack to large, low-level collection pipes, installed at a pitch, either externally or under the building floor, requiring extensive excavation and backfill; and The pitch in the pipework can be restrictive, and if long distances are involved below ground, the discharge could end up being lower than the receiving pond or main storm sewer. Points to consider for siphonic configuration Siphonic roof drains undergo extensive testing and report specific flow data per ASME A112.6.9, allowing the plumbing designer to accurately deter- E mine ponding levels; The roof drains are collected by high level manifolds that can be routed within the building, allowing for easier coordination of the pipework s with other services; The siphonic pipework drops at a preferred location, allowing greater flexibility; and Siphonic pipework is self-cleaning, as it is restricted to having the minimum flow at 3 feet per second at all times during design flow. Wavy flow - This is the operation of the system during light rain or melting snow, where the water flows into the drain below the level of the baffle plate, and the water can flow through the pipework with no back-up or restriction in flow.
ISSN:1080-353X
2328-9333