Pumps, the concept of head

[JohnMc]

I am an IT dink, so I am hoping someone here can lend me an assist on the concept of `head`.

We are settling on a piece of acreage in a couple of weeks an I will install an AP system. Now the property has spots where there is a 1-1.5m down slope I would like to take advantage of. However I don't want to run 30m of wiring to the bottom slope sump to power the pump. Rather I would prefer to place the FT next to the shop with the pump taking advantage of the electrical already in place. Then have the pump suck up from the down slope sump.

Bottom line. Are the ratings for `head`equivalent whether the pump is acting like a well pump vs an aquarium pump?

Thanks.

[ande]

Hi JM
try this link http://www.koiphen.com/forums/showth...stem-curve-etc
werry good read on head plumbing...........

cheers

this pdf also good on the matter http://www.koiphen.com/members/harve...i/plumbing.pdf

[GaryD]

Hi John,

Pumping head is the distance between the surface of the water in the vessel from which you are pumping) up to the surface of the water in the vessel to which you are pumping.

Is what what you were asking?

Gary

[Pseudoreality]

What you are looking for is a suction pump or self priming pump. I would look for a pump that can handle at least 2m of suction head. They exist, however they are generally more expensive than a pump that needs a positive suction pressure.

Head is a term used to describe pressure in piping and pumping systems in units of vertical distance (m, ft, etc). For water 10m of head is approximately equivalent to 1atm (14.7psi). Head pressure is the amount of pressure generated by the elevation difference between your pipe inlet and outlet. If you pipe goes in or comes out underwater you take the measurement from the top of the water surface as the water on top is pushing down (as Gary mentioned). Most pump manufactures publish a chart called a pump curve. This chart shows what flowrates you can get at different heads. The thing to keep in mind is minor losses from elbows, narrow pipe, etc. will also put back-pressure on your system and increase the 'head' the pump feels. For example, if your vertical distance is 1.5m, but you use 50m of 1/2" pipe and have lots of elbows, your pump could see well over 2m of head. However, in general if your system is designed properly the most significant contribution to pressure losses in a system is from the vertical head.

[JohnMc]

Ok,. Now I understand head thanks to you guys.

So here is my thinking. I could go with a shallow well pump (eg: http://www.homedepot.com/webapp/wcs/...ocStoreNum=589) as an example. Most that I see here in the States are rated for 7m depth.

thoughts?

[tpilk]

Great explanation Pseudoreality.

I'm curious about his application though - I've not had to move water laterally like this, but I could see the need in the future. My head requirement is pushing 4M.

Calculating the distance on grade affect and the additional load on the pump is certainly something to understand upfront. I've not looked for an actual chart or formula to calculate. So we've got (Hydraulics vs gravity) vs a chinese-made pump. Could be a problem...

I had just planned on an (expensive) industrial pump, instead of a pond-type pump. John's well pump idea is probably a much better solution. Definitely more expensive, but better for the application...I think. We need pump output to fall into a reasonable range for an AP system. Also, some well pumps are designed for intermittent use. I had considered pumping into a sistern (intermittently) and then the tank could gravity feed into the AP system. Some additional advantages might be off-gassing in the sistern, etc.

What do you think?

[bigdaddy]

That's not a bad idea Tpilk, I'm just thinking along similar lines for another system later on.

The 2 main concerns I would have is:

How high from the surface of the water to the surface of the cistern would you be Pumping?(For efficiency I would keep that distance as low as I could plus minimse the amount of bends and sharp bends) which you've explained.

How much power would your pump draw?

Electricity in my State in Australia has increased exponentially over the last decade and looks like it will continue at no less a rate with no end in sight so efficiency with the running costs coupled into the application is becoming more of a concern.

Cheers.

[tpilk]

Hi BD,

Straight as possible is good and realistic for me. Head is another challenge. Got to get it up the hill, but then the sistern still needs to sit high enough for proper gravity feed back into the system. I'm thinking 4m. With the well pump feeding the sistern, you have to manage the pumping, but it would be intermittent use - just need to utilize realiable switching device. The pump does not need to be excessive, just enough to get up the hill with some flow left. The sistern ideally would include a rainwater catch, which would reduce pumping (electricity needs) through some periods of the year. This type of system would lend itself to solar as well. I don't have access to AP specific hardware, plumbing or switch/controls here. I'm looking to sistern technology and industrial applications to take care if it. If you've traveled through Asia, you see thousands of water tanks lining the buildings, so at least the parts are available to me.

[bigdaddy]

Hi Tpilk,

No one really needs AP Specific switching.

If you know a good qualified electrician Then ask him/her to build you one..My advise to anyone though when you are playing with 120/240 volts or more, don't do it yourself unless you are a qualified sparky..It's just not worth it..

I look forward to seeing everything unfold as time goes by...

Cheers.

[JohnMc]

Ande, thanks for the tip on the koiphen plumbing article. Probably one of the more lucid presentations I have read in a long time on any subject.

Gary, Yes. I just assumed, wrongly, that there might be factors that differinate between suction side head and discharge side head.