Browse Forums General Discussion Re: Charged stormwater help!! 2Jul 21, 2021 8:45 pm 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Charged stormwater help!! 4Jul 22, 2021 6:01 am 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Charged stormwater help!! 6Jul 22, 2021 11:42 am That's great. A sub surface pipe is a buried carrier pipe. You can also buy 5, 15 and 30 degree 100mm DWV elbows. Irrigation shops are usually much cheaper than the big green shed when buying PVC pipe and fittings. I also recommend using the green (pressure) solvent cement (plus primer) with any charged system. DWV tees are well designed for drainage as the fittings communicate at an albeit small angle with the water in the carrier pipe plus the velocity from the downpipes won't be all that great anyway. Your 1:20 Average Recurrence Interval is most probably 160 mm/hr. This is based on an average rainfall intensity of 2.666 mm of rain per minute over a 5 minute duration. It is best to factor in a safety margin when using ARI figures when planning site drainage as they are the minimum qualifying requirement for each ARI classification. 134 (sq m) x 2.666 (mm/min) = 357 lpm. The 100mm SN6 DWV pipe has 3mm thick walls and an internal diameter of 104mm. This gives a volume per metre of 8.5 L. With a velocity of 1 metre per sec, the flow rate is 510 lpm. Looking good so far! The 90mm reducer at the end will add to the friction loss but not by a lot over its short distance. The pipe fittings also create turbulence which adds to friction losses which are expressed as equivalent pipe lengths. The 47 m distance is also thought of as friction loss when doing calculations. The downpipe closest to the junction with the 47 m pipe will have the greatest influence on flow rates, just think of the downpipes as water towers along a pipe system and their purpose. The Hazen-Williams formula is used to calculate flow rates in gravity fed pipe systems. Even if you were to have 100 m of total friction loss (you are unlikely to with an uncomplicated flow path but it could/will be close), you would still have a maximum velocity of 0.942 m/s which is 480 lpm with 0.8 m head. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 19515 Plumbers 'can be' plumbers, made all the worse by self certification which the building surveyor invariably accepts as proof of compliance! The good thing is that you know know. 3 4859 Grab a hose, insert it at the top of the inlet/down pipe and turn the water on and see where the water is escaping from. Then you'll know. 3 8465 |