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TECHNICAL INFORMATION
25mm polypipe vertical drops trap larger air pockets than 19mm drops and bubbles larger than 1mm rise in STILL WATER at a rate of one metre every four seconds. In time, these flow restricting air pockets will either calve off or rise to the surface but this creates another situation. Once primed and even at a modest one metre head, a three metre length of 25mm polypipe will flow into a tanks bottom inlet/outlet at 38+ litres per minute, an average hourly rainfall of nearly 50mm on 50 square metres of roofing, and don't forget that is from only one outlet! Unless you have a cyclone in the back yard, the reservoir level will immediately drop and the vortex, like Arnie, will be back!
The Quick Prime's use also defies common logic by acting as a vacuum breaker by infusing air from the third priority to the second priority vertical drop after full bore syphonic conditions have been established. The small bubbles are however quickly swept away and have a minor influence on capacity and velocity as opposed to the copious amounts of air present during gravity drainage which operates at near atmospheric pressure.
Maximum full bore flow will return to the second priority outlet once syphonic conditions are established in the third priority outlet.
Air flushing velocities for 19mm and 25mm polypipe are accepted as being 8.4 and 14.4 litres per minute respectively. It is a common mistake for product designers to try and overcome poor gravity fed flow rates by upsizing to larger outlets and hoses. Doing so only traps more air and a higher flushing rate requirement!
There are four stages of syphonic drainage; GRAVITY FLOW, PLUG FLOW, BUBBLE FLOW and FULL BORE FLOW. These stages are explained in the HydroMax PDF