How high can a March Pump--pump? - Page 2 - Home Brew Forums

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08-07-2009, 01:19 PM   #11
Whiskey
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Jul 2007
Granville, Ohio
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Quote:
 Originally Posted by lehr I just open a valve it takes two seconds.
Same.

It also helps a ton if you put the inlet on top and the outlet on the bottom. Liquid seeks the lowest point,and air seeks the highest point, might as well plumb it as such.
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08-07-2009, 01:44 PM   #12
thedigitale
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Nov 2008
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One thing to keep in mind is that your head pressure is determined by horizontal travel, vertical travel and and turns the flow takes.

Generally:
10 ft horizontal = 1 lb Head Pressure
1 ft vertical = 1 lb Head Pressure
90 Elbow = 1 lb Head Pressure

This means that if you want to go 6 feet directly above the pump you need a pump rated for 6 lb of HP. However, you probably have about 4 elbows on the rig, and some horizontal travel, so you're now looking at around 11 lb of HP. On a 12 lb March pump, you'll be lucky to get a trickle out of this.

If you can raise the pump a little and try to eliminate one or more elbows, you might be able to make it.

08-07-2009, 02:39 PM   #13
Whiskey
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Jul 2007
Granville, Ohio
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Quote:
 Originally Posted by thedigitale One thing to keep in mind is that your head pressure is determined by horizontal travel, vertical travel and and turns the flow takes. Generally: 10 ft horizontal = 1 lb Head Pressure 1 ft vertical = 1 lb Head Pressure 90 Elbow = 1 lb Head Pressure This means that if you want to go 6 feet directly above the pump you need a pump rated for 6 lb of HP. However, you probably have about 4 elbows on the rig, and some horizontal travel, so you're now looking at around 11 lb of HP. On a 12 lb March pump, you'll be lucky to get a trickle out of this. If you can raise the pump a little and try to eliminate one or more elbows, you might be able to make it.
My pump pushes 5' vertical with 6 elbows and a couple of t's and has no issues starting a pretty good whirlpool in my HLT. However the return is at about 4 feet above the pump which helps negate a small percentage of the head pressure.

Where are you getting the "lbs of Hp" in regards to a March pump? Head pressure on pumps is generally listed as feet "12 feet of head pressure" or occasionally PSI, head(ft)= Pressure(PSI)X 2.31. Head being the height at which the pump can no longer pump vertically through a nominal sized tubing/pipe. March rates the 809-hs at 1/2 inch tubing.

Also typically a smaller diameter tubing will add head to a pump.

Anyways its has nothing to do with lbs, a pump that has a head of 12 ft in optimum conditions will pump distilled water at 1.000, oil at .7500, or a wort at 1.070 to the same ft of head. The hydrostatic pressure will change but the head will not.

@ jlosbor. The real questions are what model of March pump is it? is it a 809-HS rated at 12ft of head or the 809 rated at 7.5? Did you buy it new or used? What kind of QD are you using and if at all possible can you post a picture of your setup? Was the container (I assume a kettle) you were pumping from higher then the pump? These pumps are not self priming, where you are pumping from must be above the inlet of the pump. They will not pull from a container that is below them.

I would do a dry run with cool water and see where the issue lies.
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08-07-2009, 02:59 PM   #14
Catt22
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Jan 2009
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Quote:
 Originally Posted by thedigitale One thing to keep in mind is that your head pressure is determined by horizontal travel, vertical travel and and turns the flow takes. Generally: 10 ft horizontal = 1 lb Head Pressure 1 ft vertical = 1 lb Head Pressure 90 Elbow = 1 lb Head Pressure This means that if you want to go 6 feet directly above the pump you need a pump rated for 6 lb of HP. However, you probably have about 4 elbows on the rig, and some horizontal travel, so you're now looking at around 11 lb of HP. On a 12 lb March pump, you'll be lucky to get a trickle out of this. If you can raise the pump a little and try to eliminate one or more elbows, you might be able to make it.
The static water pressure of one foot of water is 0.433 psi, or closer to 1/2 lb than 1 lb per square inch. It's simply the weight of the water in the column. Dynamic frictional losses are highly dependent on the type and size of the hoses or tubing. I regularly pump to above six feet at a rate of about 3-4 gpm without issues. The OP should be able to do the same if he uses larger and shorter hoses. Obviously, I've been down this road and the fix was larger diameter tubing.

08-07-2009, 03:23 PM   #15
thedigitale
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Nov 2008
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Both of the above posters bring up good points. I simplified things just to put the concept of head pressure out there, but am no engineer, so please feel free to expand on it. My knowledge of this is very general and is just a point of reference I use when buying aquarium pumps.

03-19-2010, 03:49 PM   #16
Synovia
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Jan 2009
Chicago, Il
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Quote:
 Originally Posted by thedigitale Both of the above posters bring up good points. I simplified things just to put the concept of head pressure out there, but am no engineer, so please feel free to expand on it. My knowledge of this is very general and is just a point of reference I use when buying aquarium pumps.
The problem is, its a big fluid dynamics problem. If flow is low, elbows don't restrict anything. If flow is high, they're terrible.

http://www.reefcentral.com/calc/hlc2.php

That does a pretty good job, but you'll have to figure out a pump thats close to the March 809.

The Iwaki MD20-RT seems pretty close.. 420gph max, 14 foot head. (March is 450/12 IIRC).

07-01-2010, 07:13 PM   #17
knightbeer39
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Oct 2006
Desert
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Hey, a bit off topic, but I have noticed that the pumps you get from morebeer, NB, etc. have a mounting plate already attached, so unless you mount with the plate vertical, you can't get the inlet on top and outlet on bottom. Our can you actually rotate the pump head?

07-02-2010, 01:46 PM   #18
telejunkie
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Aug 2009
vermont
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Quote:
 Originally Posted by knightbeer39 Hey, a bit off topic, but I have noticed that the pumps you get from morebeer, NB, etc. have a mounting plate already attached, so unless you mount with the plate vertical, you can't get the inlet on top and outlet on bottom. Our can you actually rotate the pump head?
Yes, the pump heads can rotate

07-02-2010, 03:13 PM   #19
a10t2
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May 2010
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Quote:
 Originally Posted by Whiskey It also helps a ton if you put the inlet on top and the outlet on the bottom. Liquid seeks the lowest point,and air seeks the highest point, might as well plumb it as such.
Wouldn't that actually be the argument for mounting it the other way around (inlet down, outlet up)? You want the pump to push air out of itself, rather than constantly re-introducing air into the head.