Water Pressure / Pump Irrigation Question

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brunion
Posts: 1
Joined: Fri Mar 02, 2012 12:28 am

Water Pressure / Pump Irrigation Question

Post by brunion » Fri Mar 02, 2012 1:42 am

I am looking at the design of the following indoor irrigation system.

I have a 1000 gallon tank of nutrients that is floor level.

The nutrient must be pumped to a level of 12 ft where it will flow level along . . .

a row is 96 feet long, there are 4 rows. Each row will be cycled nutrients using a solenoid valves.

Each row will contain 6 growing stacks (stations).

Each growing stack will have 15 grow tubes feed by a ½” dia. flex PVC reduced at each end to a ¼” dia. outlet (I cannot use typical irrigation drips because the nutrients will get clogged, thus the ¼” outlet).

My question is:

I need to make sure the volume from each of the ¼” dia. outlets is equal (not exact but pretty close) so that each grow tube gets the same amount of water and nutrients.

What GPM pump should I use to raise the water 12 ft and maintain a consistent pressure?

Should I use 2” pipe from the 1000 gallon nutrient tank to the ½” grow stacks?

Thanks,

Brett

admin
Site Admin
Posts: 371
Joined: Mon Feb 08, 2010 7:47 pm

Re: Water Pressure / Pump Irrigation Question

Post by admin » Sun Mar 04, 2012 11:13 pm

In order to have same flow rate, valves for flow rate control should be used. When you start your system than you have to balance flow rates through each pipe which means some line should be with valves more closed and some (away from the pump) with valves fully opened. Maybe if you can place valve for each station, but it depends on the layout of the system.
GPM of the pump depends how much water do you want to have on every 1/4" outlet? GPM will be the sum of all no. of outlets x flow of each outlet. Pump pressure than can be calculated but the scheme is required so pipe distances and diameters can be known.
Pipe flow calculations - since 2000

rosst
Posts: 2
Joined: Tue Apr 10, 2012 4:05 pm

Re: Water Pressure / Pump Irrigation Question

Post by rosst » Tue Apr 10, 2012 5:13 pm

If I understand your problem correctly, you have a total of 24 dispensing stations. Since you are using the 1/4" outlet instead of a standard drip point, your flow rate for each station will probably be on the order of 0.1 gallon/minute (1.5 cups, 0.4 liter/min) or even smaller (1/10th of this). Assuming 0.1 gpm x 24 stations = 2.4 gpm at the pump.

As the admin responded, placing a small manual control valve at each station is the easiest way to control the flow. However, these may also become clogged by your nutrients. An alternative that requires more set up would be to put an electrical or air-operated solenoid valve at each station connected to a timer that opens each one sequentially for a given period of time. If only one valve is open at a time and for the same length of time (a few seconds?) you can pretty well assure you are getting the same volume of water/nutrients to each station.

Your pipe header needs only be 1/2" or 1" at most for this arrangement. You could use 1" between the tank & pump, then to the beginning of each row. Run 1/2" pipe down each row to the stations.

A pump for this system can be either centrifugal or positive displacement (gear/piston). Micropump has some excellent, small pumps that will fit this use well. The total head (discharge pressure) required at the pump should not exceed 10 - 15 psig.

I hope this helps.

Ross Topliff

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