How high can a March Pump--pump?

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jlosbor

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I'm using 3/8 inch tubing, (if that makes any difference). Can't seem to get much flow above a 3 foot lift. I've shortened the tubing as much as possible but it appears that the most productive flow is 3 ft or less. Is this normal?

I had high hopes that I could pump hot water up to my HLT which is 6 ft above the pump. No way was that happening. Then I tried pumping to my mash tun, which is about four ft. Nothing doing.

It appears I have spent about $350.00 for pump, tubing, and quick disconnects to pump hot wort through my CF chiller. Whoopee.:(
 
Thanks for the replys. I'm sure I have the pump primed, I opened up all valves and let it flow downhill for a while before turning the pump on. It pumps great as long as the tubes are not raised up too high. The 3/8 tubing may be my problem.
 
From experience, 3/8" plumbing on a March suxors...
 
The small 3/8" tubing is the problem. Replace with larger tubing and keep all tubing as short as is practical, especially on the suction side of the pump. Maintain a positive suction head and the more the better.

I'm using 5/8" ID tubing throughout my system and I pump to an elevated HLT just as you are trying to do. I can pump 12 gallons up more than 6 feet in about three minutes or maybe less. I haven't timed it exactly, so that's only a rough estimate, but it's fairly fast.

You may have trouble moving liquids to any significant height if it's much above 200 F. This will vary substantially depending on specific system configurations, but these pumps are more prone to cavitating at higher temperatures. Having positive suction head makes it a lot easier and faster.
 
Put an air bleed valve like this and your problem will be solved.
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Pat
 
What is the deal with all of the air bleed valves I have seen lately? I just drop the OUT line to the same level as my IN liquid and it automatically pushes all the air out, then I connect the hose. Takes about 5 seconds.

I timed mine this morning, 4 gal/min with a 3' rise. 1/2" ID tubing
 
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.
 
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.
 
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.
 
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.
 
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).
 
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?
 
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
 
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.
 
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