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colonel_sanders

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Thursday, December 7th 2017, 10:29am

NEWB: new sprinkler system design

Hello!




I'm designing and installing sprinkler system for a bit of fun for my in-laws over christmas. They're getting a bit older and I reckon it'd save time and water not watering their garden by hand. I need a bit of help figuring out the details.




The garden is 850sqm. We have access to a natural water source that's very shallow and flows in at 6L/min.




There is a 720L tank dug into the centre of the garden that I'll use for the sprinklers. Its about .8m deep (3ft ish). The tank is refilled by a small water pump that is already operational. It takes about 2 hours to fill the tank (at the 6L/min flow rate of the natural water source). My idea is to fill the tank and activate the sprinklers multiple times during the night so I get about 2100 L / evening on the 850sqm property. Installing a larger water tank or pumping directly from the water source is not an option.




The property has about a 1m (3ft) slant.




I've calculated the elevation head as 6ft.




My design pressure is 50 PSI.




My pumps HP is 1.




My design flow is approx 18 GPM (68 LPM).




I'm thinking of purchasing this pump (1 HP, centrifugal water pump) as its really cheap and seems like it would do the job. I don't mind spending more money, but if this will do I'm happy just in case I burn it out experimenting. Its a Chinese pump with the model QB80. Mixed reviews:

http://www.ebay.co.uk/itm/151116-Centrifugal-Peripheral-1-HP-Water-Pump-For-Home-Pond-Garden-Farm-Tank/272339693613?epid=1084253487&hash=item3f68b5f02d:g:HJQAAOSwX61ZCUwI




I'd like to use Rain Bird 1804 VAN sprinklers, spaced approx every 3.5 meters (12 feet). I've chosen these because I have heard they're quieter than Rotor Heads (as the system will be operating in the evenings), also there a lot of obstacles in the garden (random art installations that move from time to time) and I thought more of these sprinklers spaced at shorter distances would have a better chance of coverage. I'll need 30 to cover the property. Each sprinkler consumers 2.6 GPM at 30 PSI. I will run these in 4 zones of approx 7 sprinklers (grass in the shade, grass in full sunlight 1, grass in full sunlight 2, and vegetables).




The tank is located in the centre of the garden, the pump will be placed next to the tank in a wooden box. I will place the valves for zones as close to the pump as possible. A 1" Polythene tube will be run from the pump to the valve manifold.




Each zone of 7 sprinklers will use a run of 100 ft 1" Polythene tube, resulting in a pressure loss of about 10 PSI.




I'll be attempting to build by own irrigation controller from an Arduino chip as I'd like to build water sensors in to the controller to stop and start the pump / valves when the water tank is empty / full.




By the way, I'm based in Europe!




Any advice on how to continue or if I'm thinking wrong about this would be greatly appreciated. I'm hoping to start buying materials next week to install by the New Year… I've don't have any experience with irrigation, but I'm hoping that I'm on the right track!




Cheers!

colonel_sanders

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Thursday, December 7th 2017, 10:29am

Formatting

Sorry about the spaces in there! Formatting changed when I posted it :/.

Wet_Boots

Supreme Member

Posts: 5,147

Location: Metro NYC

3

Tuesday, December 12th 2017, 6:43pm

You might rework your designs to employ agricultural drip irrigation, and get the quietest operation possible. As far as the pump goes, forget the eBay toy and use a small sump pump. They already come with a float switch, so they won't pump your source dry.

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