Greenhouse irrigation pumps
 

I am looking for a continuous duty pump that is fit for drip systems. I currently have pumps and pressure tanks, but am looking for a consistent pressure. Does anyone understand pumps for this need? Or am I better off to use a pressure tank? Can you set the pressure on a CD pump?
I have looked at Dolphin pumps, but cannot find the info on pressure settings.

A lot of pumps that produce pressure are made for high-pressure aeroponics, which is about 35 psi. At that pressure, when forced through a mister head, the mist will atomize, breaking into the smallest droplets that hang in the air for the longest time. Smaller systems use a small accumulator tank and a small pump. Larger systems have a big pump on a cycle timer, like a shallow well jet pump.

Do you know the psi you need? I doubt you need it as high as 35.

[QUOTE=Cole_Robbie;624431]A lot of pumps that produce pressure are made for high-pressure aeroponics, which is about 35 psi. At that pressure, when forced through a mister head, the mist will atomize, breaking into the smallest droplets that hang in the air for the longest time. Smaller systems use a small accumulator tank and a small pump. Larger systems have a big pump on a cycle timer, like a shallow well jet pump.

Do you know the psi you need? I doubt you need it as high as 35.[/QUOTE]
I want it above 30, my pressure regulators will check the pressure if it is higher. I can set my PT's to do that, but then I just use my switches too death.

Your cheapest pump will be a shallow well pump from a Home Depot/Lowes type of store. They are about $200. They're not meant for irrigation, though, and the new ones have internal shutoff switches for when the pressure gets too high, due to flow being too low. To get around that issue, you can plumb a T into the line and place a pipe going back to the original tank with a valve. Open that valve a little to relieve pressure off the pump. Once you get it right, you shouldn't have to adjust it any more.

The advantage of using a big pump is that you can use plastic tanks, which are a lot cheaper. If you used a small pump and an accumulator tank, it would have to be made of metal in order to hold pressure, and thus would be a lot pricier. If you use a well pump, plan on it having its own dedicated 15 amp circuit.

Or just build a water tower :) A cheap sump pump will have up to 20' of lift. Once the water is in the air, you have pressure to tap, without having to charge the tank with a pump.

What I have now is shallow well jet pumps from 1/2 horse to 1 horse, but they call for a pressure tank, which leaves a slight variable flow. What I want is a continuous duty that operates between 30-40 psi if possible. I just burned out a switch because the pump clicks off and on, even with 35 gallon pressure tanks.
I will read through your post carefully, maybe I can figure something out.

That's what I'm talking about with the release valve plumbed back to the tank. It stops the clicking.

You don't need your irrigation to run constantly, if you just put it on a timer with short cycles. You can set the on time and off time to be whatever you want. If you do it that way, you don't have to hold pressure in a tank all the time, and it makes it all a lot cheaper. There are all kinds of cycle timers. The best ones look like a metal shoebox, with big metal mechanical gears inside, a couple hundred bucks. Cheap plastic ones tend to fail.

My irrigation is on solenoids that feed back to a control box that has stations. It works good, but I am wanting to perfect the flow. I'll post a pic later of what I have, then maybe it will be easier to digest what I am asking. As usual, I appreciate any and all feedback.

Have you considered a variable frequency drive pump. Unless you exceed the capacity of the pump, it will hold a constant pressure that you set and will slow down or speed up to meet that goal. They are not cheap.

It would be easier to just switch to aeroponics.

[QUOTE=Rockandrollin;624484]Have you considered a variable frequency drive pump. Unless you exceed the capacity of the pump, it will hold a constant pressure that you set and will slow down or speed up to meet that goal. They are not cheap.[/QUOTE]

That is what I want, yes. When the solenoid goes off I want the pump to maintain pressure until they go off. Maybe I used the wrong term by saying continuous duty. Do you have a page I can look at? I have been eyeing the Dolphin pumps, but cannot determine the PSI.
Here is the current set up, I am not sure if I can bypass the pressure tank with these cheapo pumps? I can run 572 drippers at once without outdoing the pump capacity.

I am not a pump guy, so like I said all ears.

[QUOTE=AKmark;624429]I am looking for a continuous duty pump that is fit for drip systems. I currently have pumps and pressure tanks, but am looking for a consistent pressure. Does anyone understand pumps for this need? Or am I better off to use a pressure tank? Can you set the pressure on a CD pump?
I have looked at Dolphin pumps, but cannot find the info on pressure settings.[/QUOTE]

Yes they do and I went back to your original question to answer it.
The pump you are looking for is a centrifugal pump with an adjustable pressure relief valve that is piped back to the tank.
An alternative to the pressure relief valve would be a globe valve that you can open and close to adjust the pressure going to the field.
You want to make sure you dont boil the water coming out of the pump due to cavitation so this water has to go somewhere.
On the good side it can warm the water up for you.:lol:
Steps pick out pump.
Put valve on down stream side of pump.
Put gauge in line after pump.
Adjust valve by way of gauge reading.
DO NOT over estimate what pump sized you need bigger is not better.
This will only wear out the pump due to cavitation.
Your well pumps can keep the tank filled.
Worth

What kind of controller is that if it is irrigation and you aren't maxed out you can get a pump start relay.
Or you can just connect it to the same zone as the valve for the drip system.
[URL]https://www.google.com/aclk?sa=l&ai=DChcSEwiXqMOYqs3SAhVSSw0KHQKhAJYYABALGgJxYg&sig=AOD64_3VKav98ecbZ-TwCxO9LEfDiwLdaA&ctype=5&q=&ved=0ahUKEwipsL-Yqs3SAhWCJCYKHdymDfkQvhcIJg&adurl=[/URL]
This is just an example.
Any relay that fires off of 25VAC and can handle you currant draw on the pump will work.

Mark,
I've learned a thing or 2 about pumps, and have a couple products on the market based on pumps.
I see you want 30 psi, what gpm range do you want at that pressure?.
Should be able to hook you up with something.
Nematode

[QUOTE=AKmark;624498]That is what I want, yes. When the solenoid goes off I want the pump to maintain pressure until they go off. Maybe I used the wrong term by saying continuous duty. Do you have a page I can look at? I have been eyeing the Dolphin pumps, but cannot determine the PSI.
Here is the current set up, I am not sure if I can bypass the pressure tank with these cheapo pumps? I can run 572 drippers at once without outdoing the pump capacity.

I am not a pump guy, so like I said all ears.[/QUOTE]

Sorry, I am not a expert in this area. Your best best is your local pump person and google.

What I was referring to would replace your well pump and pressure control with a new pump and a variable frequency drive. They do require a pressure tank but are tiny compared to a conventional system, they are like 1 or 2 gallon.

They are becoming more common for residential well pumps. You mentioned you are in the 1/2hp to 1hp range which is a typical home pump size.

Their biggest benefits are having a constant pressure and much more economical to use. Your current well pump goes from 0 to full power in a second and the opposite when the pressure switch opens. These pumps are variable and ramp up down to maintain pressure and if need be will cycle off.

[QUOTE=Nematode;624523]Mark,
I've learned a thing or 2 about pumps, and have a couple products on the market based on pumps.
I see you want 30 psi, what gpm range do you want at that pressure?.
Should be able to hook you up with something.
Nematode[/QUOTE]

Awesome, I need at least 10GPM, I could get away with a bit less because I have an overkill with stations and solenoids. I have been looking at this for sometime, so anything can be helpful. I need somewhere between 30-40psi, not under 30 though.

I can use inline, or shallow well, unless you have a different idea.

Thanks everyone, when I get this dialed I will certainly share the info.

That is centrifugal territory for sure.
Can you power the pump only when a valve is open?
This makes things a lot easier.

Yes, they just sit there until something is opened and pressure drops. I want a pump that powers up instantly, tries to maintain a set pressure, and does NOT operate on a high low range of pressures, like 20-40, 30-50 etc.

I would start with the pump you have.
Just get rid of the pressure switch and air tank.
Power the pump ONLY when a valve is open.
This will require a contactor that closes and powers the pump when any of the valves are open. Irrigation controllers usually have a signal output for this.
Not sure what your controller is.


Do not dead head the pump or power it against a closed output. Bad things happen.
You can use a pressure relief valve plumbed back to the tank to prevent this problem.
Set it at 40 psi and use it as your pressure regulator.

If the cast iron pumps arent holding up to the chemicals there are reasonable stainless models available.
Bur cam 506518SS looks ok
True value and amazon has these. About $200

Thanks Nematode, I'll look into it. The pumps only get fresh water.

You seem to want an exact output pressure, a relief valve might get you there, but if it is not precise enough, a pressure reducing valve can be used in addition to the relief valve.
Wilkins nr3xl is adjustable 15-75 lbs. 1" should do the job.

OK here is another way.
Use a cycle stop valve and a very small pressure tank.
My irrigation is set up this way.
Pump is powered always and has a 40/60 pressure switch.
Valve opens, pressure quickly drops from 60 to 40, pump turns on and stays on with pressure at 50psi until the irrigation valve closes. Pressure builds to 60 and pump turns off. No need for pressure relief valve. Cycle stop valve is adjustable.

Im not sure if the pressure variation is a problem.

One more and I promise I'll quit. Insomnia sux.
506532SS bur cam.
Drop it in and remove your pressure tank. Its a "constant pressure" unit.
Looks like a cycle stop type valve on the output with an electronic control.

Cant find the exact pressure spec but there is a customer service number in the install instructions.

[url]https://www.google.com/url?sa=t&source=web&rct=j&url=http://pdf.lowes.com/installationguides/772910065324_install.pdf&ved=0ahUKEwj8hvKYh87SAhVq54MKHRhWAMkQFggwMAM&usg=AFQjCNFqgoDxPOACXPhpTaYuAZdEQjL_Cg&sig2=5OMEU3Hp1qzO6VMtOCRalA[/url]

$270

One thing you need to do first is to get rid of the irrigation valves you have maybe.
You need ones with flow control.
This will give you the exact output pressure you want.
These are the ones I use.
They can be used from .025 to 30 GPM.
[URL]https://www.sprinklerwarehouse.com/Irritrol-Sprinkler-Irrigation-Valve-p/2500tf.htm[/URL]
All irrigation controllers have what is called a Master valve/Pump start station.
What you will see on them is the connections for the power (maybe) two connections for the rain sensor (jumped out), the master valve and then the stations for how ever many stations you have.
And a common for all valves.

There are two ways you can connect the pump start relay.
One is to wire it parallel with the master valve.
The other is to wire it parallel with the valve that controls the drip system.
Both will work.
Connecting it to the master valve the pump will always come on anytime a station comes on.
Connecting it to a station it will only come on when that station comes on.

Here is a description of one.

[LIST][*][B]Electrical relays for both low voltage (24V ac) control switching and high voltage (120V ac or 240V ac) main power contacts[/B]
- Allows remote pump switching using 24V ac output from an irrigation controller’s master valve/pump start circuit
- Opens and closes main power contacts for pumps (1HP at 120V ac 1 Phase or 2HP at 250V ac 1 Phase)
- Note: 2HP at 120V ac will exceed maximum amp rating.[*][B]Highly efficient 0.1 Amp operating requirement[/B]
Draws less holding power than most solenoid valves[*][B]Can also be used with the Irritrol PC Control system for switching control of low voltage landscape lighting[/B]
Saves the expense of an extra timer and puts irrigation and landscape lighting control in one location on the owner’s computer[/LIST]

Thanks guys, I really appreciate the time you spent helping with this, I will let you know what happens.