Homemade water pump?

[zmoz]

In my barn I have a terrible water supply that only offers about 150 gallons/hour max flow. That's not enough for equipment washing, tank filling, or even using a pressure washer. It also won't do squat in the event of a fire.

My solution to this problem has been ten 55 gallon drums all plumbed together, which fill up slowly as a reservoir and then I use a pump to power my "hose". I use the hose mostly to water things and clean equipment.

I have gone through more than a few cheap crappy electric pumps and I'm tired of dealing with them. They never live up to the advertised specs, it's either flow or pressure, not both. I've even tried using multiple pumps in series. Ideally I would like to push at least 1000GPH out of a heavy duty 3/4" garden hose at 50-100 PSI.

So, I have decided I need to make a gas powered water pump for my tasks. I was thinking about using this roller pump from surplus center along with a 5hp engine:
https://www.surpluscenter.com/item.asp?item=278-CP&catname=water

Obviously I would have to belt drive it to slow the pump to 1200 RPM max. Does this seem like an appropriate pump for what I want to do? I don't know much about "roller" pumps, but this one seems to offer a ton of output and pressure for a reasonable price. What difference does the number of rollers make? I already have the engine. Will this thing truely put out 17.3 GPM at 100 PSI like it claims to? Is a pump like this "self priming"?

 

[bobodu]

Looks okay to me..roller pumps are a variation of vane pumps.

Be sure to have big enough pipe between those barrels!! You might even wanna look around for some of these tanks.

http://fortwayne.craigslist.org/grd/2219427585.html

 

[GE222]

Seems like from the specs, it should fill your needs. Yes a belt drive will be required to rum the pump at rated speed. It is difficult to tell from the picture how the pump mounts.

With your current reserve being a bank of 55 gallon drums, I'm curious if you have had to worry about corrosion from them. An inlet filter might make the pump last longer. A large poly tank might be a better long term one, although they are a bit pricey.

Self priming isn't listed. It will be determined by how high the lift is, which the specs don't address. Keep the tank level above or very close to the pump height.

 

[zmoz]

Yeah, I'd love to have some of those square "tote tank" things but I've never seen them that cheap around here. They're usually more like $150 or so. I'm thinking this summer I might use a small above ground pool as a storage tank.

The drums I'm using now are plastic so there are no corrosion problems. They have 1" pipes between them.

 

[SandburRanch]

I didn't see any horse power requirements on the spec. sheet. It may pay to do some investigation on that. I hooked a smaller Briggs engine to a small roller pump years and years ago and it wouldn't pull the load. It's been too many years ago to give you any experienced details.

 

[zmoz]

I didn't see any horse power requirements on the spec. sheet. It may pay to do some investigation on that. I hooked a smaller Briggs engine to a small roller pump years and years ago and it wouldn't pull the load. It's been too many years ago to give you any experienced details.

It says "4.51hp max", I assume 5hp should be alright as long as I keep the speed within spec.

Surplus center also sells this centrifugal pump rated to pump a little more water, but it's a bit more than I want to spend:
https://www.surpluscenter.com/item.asp?item=2-1222&catname=water

Does anyone think that (or anything else) might be a better option? Most of the cheap gas powered water pumps I find are meant for moving high volumes, but very little pressure...

 

[rScotty]

In my barn I have a terrible water supply that only offers about 150 gallons/hour max flow. That's not enough for equipment washing, tank filling, or even using a pressure washer. It also won't do squat in the event of a fire.
I have gone through more than a few cheap crappy electric pumps and I'm tired of dealing with them. They never live up to the advertised specs, it's either flow or pressure, not both. I've even tried using multiple pumps in series. Ideally I would like to push at least 1000GPH out of a heavy duty 3/4" garden hose at 50-100 PSI. Will this thing truely put out 17.3 GPM at 100 PSI like it claims to? Is a pump like this "self priming"?

Here's some pump info from an old engineer:

But before I get started, you have 5 hp, a 1200 RPM limit, a roller pump, and you want to end up with a system that is as good as the suburbanites enjoy. Sure, that will get you there. A bit of overkill, actually. There are easier ways, but sure nothing wrong with having too much of a good thing.

Pressure versus flow is always a tradeoff. It's called a linear relationship - meaning that if you double one you get half of the other.
The theoretical formula is HP = (psi x gallons per minute)/ 1714.

That's theory, which just means nothing is going to beat that, and in fact nothing really comes close. There are frictional losses everywhere....particularly in the hose. Any engineer just immediately knows to double the power requirement. Maybe a bit more if the motor is old and the pumps are cheap.

By the theoretical formula you can say that one horsepower will give you about 50 psi at 30 gallons/per minute. In the real world and to avoid disappointments I'd say that what you will really get for that HP will be about 40 psi and maybe 15 to possibly (unlikely?) 20 gallons/minute. For reference, that is an impressively good flow out of a 3/4" garden hose on a good farm or city system. So your 5 hp motor will be suitable. Just a matter of picking your pump. BTW, the HP equation doesn't care if you are using or making HP - you can think of it as how much horsepower it takes to make that flow...or as how much HP you could create by running that flow backwards through a pump!
In fact, a power-generating water turbine and a water pump look very same. I even know of some installations where pump and generator ARE the very same piece of machinery with the pump motor becoming a generator when the flow turns it backwards.....Rambling now....

Pumps come in low and high pressure types depending on how the water is moved along. If one stream of water is sped up and made to carry another stream of water with it - like in jet pumps or centrifugal pumps - then those type pumps are pretty much limited to being a low pressure and high volume application. Garden hose stuff. With those pumps you won't get more than about 100 psi even with a huge great big motor...Fire trucks are the top of the line for that type of pump....but you sure can get a lot of flow. They are rarely really self priming even if they advertise that they are. Very durable pumps, though. Both the pressure and the flow are RPM related, but in general if you try to develop much pressure it will really hurt the flow. These pumps like high volume & low pressure

The other type of pump is called 'positive displacement". These types are like rapid fire machine guns in that successive chunks of water are defined by boundaries and then forced down a hose one after the other so close together that it looks like one stream. we call that "positive displacement". Examples of that would be piston pumps, roller pumps, and the various gear, vane, and swashplate pumps. These pumps all have high pressure at lower flows. Their high end depends on the strength of the pump casing and the closeness of the tolerances between the parts inside. Generally they are going to be from 300 to 5000 psi depending on the inside clearances and housing strength.. Each one of these pumps will tend to pump at a specific pressure so increasing the RPMs means only a little more pressure but mostly more flow. These types of pumps will pump air as well as water - more or less - and are self priming.

Self-priming means that the pump has lowered the atmospheric pressure in the imput line enough so that air pressure can push water up to a pump. Only positive displacement pumps can do this effectively. The real world limit on this is about fifteen vertical feet. We can go into why that is if you want.

Sizing your pipes: You do that by water velocity. Figure out how much water is in a foot of pipe and how fast you are going to have to move the water to get the flow rate you want. Make the suction lines twice the diameter of the the pressure lines.

Number of rollers: Not much difference. It's a faster firing water machine gun which smooths out the flow a bit. Makes a difference if the output hose is short, but a long hose also smooths the fluctuations.
More questions? Did I miss one? Or is that enough pump stuff?
Enjoy! Roger L.

 

[Egon]

Check out your local submersible pump store and see if they can make up a pump that will meet your needs.:thumbsup:

 

[greasemonkeyok]

Thanks for the post rScotty, very informative. We have an old "out of use" irrigation system from the pond up to the garden and an overhead water tank. In the old days, we had a boiler-feed pump powered by 3 hp electric motor into 1" galvanized pipe. That system was perfectly matched because it would really move the water.

Now we are looking at 1 1/2 " pvc and installing a new pump and motor. Problem is the head pressure, uphill for a lateral distance of about 1,000'. We haven't measured the rise yet, but it looks to be well over 20'.

 

[rScotty]

Thanks for the post rScotty, very informative.
Now we are looking at 1 1/2 " pvc and installing a new pump and motor. Problem is the head pressure, uphill for a lateral distance of about 1,000'. We haven't measured the rise yet, but it looks to be well over 20'.

That sounds like a nice system. With 20' of rise and all that length there isn't much chance of reliable self-priming.... so you'll have to push the water from below.

That larger 1 1/2" plastic pipe really helps. Because we figure the pipe friction in feet, we get to simply add the pipe friction and elevation rise together. Then the total loss just depends on how fast you push the water through it. If the water goes slow enough then the pipe lenght hardly counts, but that only works for some sort of tank being filled 24/7. For a fast fill system the pipe length really hurts and your system sounds like it is filling at maybe 10 to 20 gallons/minute. That's when you want big pipe. Your 1 1/2" inch PVC is about ten times better than 1" PVC for that application. That's worthwhile.
Roughly, that 1000 feet of pipe length will act like higher elevation rise. So think of it as adding at least as much head as the elevation rise and maybe up to four times as much. Depends on fill rate. Even at 4x, these are small numbers we are multiplying so this is a doable system for normal motors and pumps.

BTW, for irrigation I've been using the grey electrical PVC from Home Depot for awhile. It comes in a thicker wall with a higher pressure rating than the white PVC, uses the same fittings, costs negligibly more, is in 20 foot lengths with belled end that saves one joint/section, and is UV resistant. Same glue works for it. Plus it's not so ugly.

Pumps always have a "pump curve" available that shows the relationship of head pressure (always in feet) versus flow rate for each horsepower for that pump - and sometimes for each rotor diameter as well. Take a look and choose one. Only thing is to first figure out your maximum head due to pipe and rise and make sure the pump+motor can basically do that. After that it's just a matter of how much you want to spend to fill it faster.
Good Luck! rScotty