Gravity weir flow generates a vortex that spirals air and water down a pipe’s inner wall. For this reason and unless flow restricted, drain pipes never contain less than 2/3rds air!
The anti-vortex baffle blocks the vortex, allowing the pipe to flow full of water. The gravitational pull on FULL FLOW sucks water into the outlet at high velocity, dramatically increasing flow rates.
Purging the air to achieve syphonic flow
Water above the baffle stops the vortex, trapping a large air pocket in the pipe. The air pocket’s buoyant force is equal to the weight of the water it displaces and it initially resists the head and the downward flow. Inflowing water creates turbulence and calves air bubbles off the air pocket and carries them downwards, reducing the size of the air pocket until it has negative buoyancy and is purged from the pipe. Syphonic full flow is then established.
SUPADIVERTA syphonic flow
- small pipes transferring large quantities of water
A vertical 1 metre long 20mm PVC pressure pipe connected to a Supadiverta outlet will discharge at approximately 58 litres per minute. This is equivalent to a steady 99mm of rain an hour falling on a 35 square metre roof area. 1 mm of water on 1 sq metre = 1 litre. Maximum flow rates through a connecting larger pipe servicing either one, two or three vertical drops depends on the available head pressure and the length and size of the larger pipe.