Need a small water pump

majorcatfish

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the water tank is it rated for air pressure? like your diagram especially having a filter shuflow pumps are great do recommend a square d pressure switch...

keep up the good work....
 

Ridgerunner

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It's been almost five decades since I studied Fluid Mechanics and Hydraulics in college. That was not my field of expertise and I did not keep my textbooks. There are several others on here that have a lot more practical experience on this topic than I do. I did work side by side with people doing this kind of stuff on oil facilities so I did pick up a bit from them but I'm not a designer of water or gas pressure systems. That won't stop me from commenting.

It is not the volume of water that gives you pressure, it is height. Each foot of water column gives you about 0.43 psi. If you use an open to the atmosphere water tank so all you have is water column the level in that tank would have to be pretty high to get any spray action. That type of system is probably more suited to a drip irrigation system.

You lose energy (pressure) from friction as the water rubs against the inside walls of the pipe. The rate of pressure loss is directly related to the diameter of the pipe and the speed of the water (or other liquid or air). Rough spots in the line can cause more friction, such as seams, valves, and other fittings. Don't be surprised if the pressure at the far end of your line is noticeably less than your near ones.

When the water is flowing, a change in diameter can cause a pressure drop. You are OK going from a larger diameter to smaller, but avoid going from smaller to larger. We called that a choke and is used to reduce the pressure of a flowing stream of liquid or gas. There are other forms of pressure regulators.

Water is an incompressible fluid. A tank full of water is not going to explode even if it breaks open. Air or any gas is compressible, it releases a lot of energy as it expands. It can be pretty violent or even explode. When you have a tank partly filled with water and partly with air with that air pressured up you are dealing with a compressible situation. You are not dealing with that much pressure. I suspect @majorcatfish , @Lickbranchfarm probably @seedcorn and others deal with those on a regular basis though I also suspect they prefer hydraulic systems. If you go with a system pressured with air make sure that every component of that system is rated for the pressure from shutdown valve to shutdown valve. That includes tank, fittings, water pump, and air compressor. With the pressure you are working with I really don't consider it that dangerous. The same thing is true of a pure hydraulic system, everything needs to be rated for the pressure it will see.

If it were me I would give a lot of thought to setting up an atmospheric water tank on a elevation (so there would not be any backflow if you had a pump failure) and use a water pump, basically what you started with. I think it is the simplest system, will probably be easiest to maintain, and probably more dependable. I would suggest a level switch in the tank that shuts off the water pump like Major suggested. @majorcatfish or @Lickbranchfarm or others do you see any need for a pressure switch downstream of the pump to shut the pump off in case of a downstream pressure loss?
 

SprigOfTheLivingDead

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Thanks @Ridgerunner . That's a lot of great information.

For clarity I ran outside to snap two pics of the area I'll be growing in. It used to be a cornfield. As you can see it's a slight grade; probably not enough to create a lot of pressure but enough to help and not create a backflow problem

As you can probably picture I will build a short platform on the top for the water tank

view from the top
topgrade.jpg

view from the bottom
bottomgrade.jpg

sat view
field.jpg
 
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majorcatfish

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@SprigOfTheLivingDead you have a good plan,,,
since i have time to this morning did a little doodling ....yes the engineer come out

from the water source to tank this is completely optional....
1. would install a check valve/backflow just in case the power goes out and if the well is used for drinking water. there would be any back flow from the tank and contaminating it.. osha reg
2. add a solenoid and pressure switch. so if you are not watching over the watering, the tank fills up the pressure switch will turn off the solenoid once it has reached the setting on the switch..and turns on when the pressure drops.
3. not on diagram 3/4" unions between check valve and pressure switch...

from tank to water lines.... you have it spot on..... once again this is optional
1. added 3/4" unions at the tank and after the pressure switch...reasoning is if you build everything in between on some type of platform you can disconnect it at seasons end and keep it out of the winter elements...
2. added 300 psi ball valves yes a little overkill but they will last you a lifetime..recommend apollo brand
3. when wiring up the system that you wire the pressure switch and then to pump... i'm sure you knew that
4. as @Ridgerunner mentioned lose of water pressure at 400' very good point.!!!! the first trees would get lets say 30psi at the end of the line it would be a dribble, if you move the main water line to the middle of the 400' and install a 3/4" tee and a 3/4" ball valve on each side of the tee, you shut one and now you are only watering 200' of line less pressure drop= better watering. once thats sides done close that valve and open the other...

this is just me, watering can be time consuming and if you get side tracked or whatever a programmable sprinkler timer would be a wonderful addition and when the nursery grows you can add more to it... the only things you would need to switch would be the 3/4" tee to a 3/4" 4 way and solenoids/wire as needs...

if you ever wanted to add a liquid fertilizer tank to the drip line you would need to install another check valve between the main tank and the tank union...osha

as for the wiring <120vac> would make sure all of it is run though liquid tight or plastic conduit....

IMG_3016.JPG

just my 2 cents worth......
 

SprigOfTheLivingDead

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wow! Thanks @majorcatfish !!! Good callout on the pressure drop over 400'. I was toying with the idea of doing two 400' lines next to each other where one waters the first half of the row and the other waters the second half. It would call for more piping, but also help with the pressure.

I have zero experience doing any of this, so don't assume I know anything about using a pressure switch or ball valves ;)
 

SprigOfTheLivingDead

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in your 3rd map where is your water source? have a couple more ideas for you...
My plan is to fill the water tank as needed via hose from our house (200-300') away off the bottom side of that 3rd map.

I am planning on digging a trench and laying a water pipe under the ground out to the tank area. Not sure if I'll get to that this summer or not.
 

majorcatfish

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went back and read your thread....starting a tree farm...

if i read it correctly you are going to grow these trees.... quote.." I hope to be providing several hundred trees a year to my local groups and helping to support this ecosystem"
with that said...are you planning to sell or give away these trees to the your local groups ? in the long run on selling to the public down the road?.

the reason i'm asking this.. you have a great piece of property to start off as a "
Nursery Stock Grower" but as things expand into more than your initial goal.
start growing multiple different species on top of local species..

you have a great plan on the watering system start up, would look into the future and see what the cost would be to have a well dug on the property to supply the nurseries irrigation needs, instead of running off the house well.

going to hold here till i hear back from you...



 
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