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Chin_Lee
10-08-2004, 12:52 AM
Does anybody know what the gph is at 14' height for a Mak 4? I can't seem to find any graphed specs for the Mak 4 or Mak 5 on the web. The only info I have is 100gph at 5 feet from JL's descriptors.
Thanks
CWLee

Invigor
10-08-2004, 01:15 AM
I can't find any charts either, but if you can get to a store that sells them, the head pressure chart is right on the box.

Skimmerking
10-08-2004, 02:47 AM
I just spent the last 45 mins looking on the net and i have came up with
1180 @4'
590@8'
295 @12'

Here's something try running the return line to a 1/2" pvc would that help it says that it will run at 22 ft so shrink the line..

from looking at the site im guessing this sorry i couldn't copy the link .may be i am reading it wrong
but a pressure pump for that.i don't know sounds funny eh...


HTH

sorry i couldnt help ya out .

mike

hockey nut
10-08-2004, 07:20 AM
ok..... looking at the mak 4 box , and if grade three was good to me , my calculations are 450gph at 14 foot head. Or something like that. max feet is 22 for a mak 4. On the box it is in meters and litres per minute. So worse case here, lets say 5 meters is close to 14 feet x 32 litre per minute as according to the box. so 60 min x 32 = 1920 ltr per hr, divide x 4 for gallons = 480 gph. again this is a rough estamate. HTH

hockey nut
10-08-2004, 07:39 AM
oops. Just go to RC and look down bottom left for head calculator and pick your pump and head hight etc. Their calculator said 700+ gph for 14'. :eek: very nice. of coarse that depends on your plumbing. cheers

Tang_Man_Montreal
10-08-2004, 03:39 PM
Here you go...

http://reefs.org/library/pumps/pumps/genx_mak4_curve.jpg

Skimmerking
10-08-2004, 03:46 PM
Well that Sums it up pretty nice
Well done there Tang MAN .



mike :mrgreen:

StirCrazy
10-08-2004, 09:43 PM
Here's something try running the return line to a 1/2" pvc would that help it says that it will run at 22 ft so shrink the line..

mike

Mike, by reducing the line size you actually add head to the equation by creating more frictional loss. if you want to reduce the head caused by frictional and shear you have to increase the pipe size. so lets say you had a 5 foot rise with 3/4" line and a few elbows and such that added up to another 2.5 ft of head your total head would be 7.5 foot. by decreasing the line size to 1/2" you will raise that to ~9ft of head and by increasing the line to 1" you could lower it to ~6.5 ft of total head.. these numbers are off the top of my head so don't use a head calculator and say I'm wrong with my numbers please :mrgreen: the intention is an approximate example of how changing line size could help.

Steve

Canadian Man
10-08-2004, 11:09 PM
On another note if you also increase the size too much then it will add water weight restriction.

Let's say you plumbed a 10ft vertical in 2" pvc than that water would weigh alot as well.

I think :biggrin:

stephane
10-09-2004, 05:37 AM
Bigger the pipe the less you will lost your flow as water will travel more slowly inside the pipe so you eliminate a lot of friction.

Canadian even if the pipe is 20 inch wide the pump will not see any difference. Pump are only sensitive to the head and friction not the size of the pipe.

pressure in watter calculate in height not in wide, you will have the same pressure 20 feet deep in a pool than 20 feet deep in a 20 mile long lake

StirCrazy
10-09-2004, 05:41 AM
pressure in watter calculate in height not in wide, you will have the same pressure 20 feet deep in a pool than 20 feet deep in a 20 mile long lake

thanks Stephane :mrgreen:

Steve

Canadian Man
10-09-2004, 06:09 AM
So you guys are trying to tell me that if you add 1000x more water in a pipe that extra water weight won't add to the back pressure on the pump?

I understand your point stephane. I do think that at some point it would add more weight to the situation.

Maybe I'm a loonie :rolleyes:

stephane
10-09-2004, 06:26 AM
So you guys are trying to tell me that if you add 1000x more water in a pipe that extra water weight won't add to the back pressure on the pump?

Exacly :eek: I know it's hard to understand when a french like me try to learn it to you but it is part of physic.

1/4 inch pipe 10 foot heigh head will have the exact same head or bottom pressure than a 10 mile wide pipe by 10 foot height. Your pump impeler is inside the water so it dont see the ouside weight. In fact it will be a lot easy for the pump to use the 10 mille pipe as it will have absolutly no restriction so you will have more flow than that 1/4 pipe :eek:

stephane
10-09-2004, 06:35 AM
One last try :mrgreen:

if you try to put your finger to stop a leak from the ouside botom of a 2 mille wide x 2 feet deep tank it will be a lot easy but try do the same ting on a 30 foot heigt by 1 inch pipe.

Canadian Man
10-09-2004, 03:39 PM
OK OK :lol:

StirCrazy
10-09-2004, 03:44 PM
So you guys are trying to tell me that if you add 1000x more water in a pipe that extra water weight won't add to the back pressure on the pump?

I understand your point stephane. I do think that at some point it would add more weight to the situation.

Maybe I'm a loonie :rolleyes:

pressure is determined by the hight of a water column and nothing else. for an example lets say we have a tank that is 24" tall and 5" wide and 5" long that is full of water. to make up a number lets pick that the pressure on the bottom glass is 2psi. the volume of water is ~9L so the weight of water is approximately 21lbs. now take another tank, say 24 tall x 25 wide and 65 long. the volume is 590L and the weight of this tank will be ~1300 lbs, but the PSI on the bottom of the tank will still be 2psi.

the reason increasing the pipe size reduced head is because it reduces the amount of water subjected to shear. because water is composed of molecules that want to stay together when water moves it shears away from the water around it. also water will try to stay to the side of a vessel by a atomic attraction. so to get the water in the pipe to move you have to shear it apart from the water against the edge of the pipe which results in friction. by increasing the diameter of the pipe you are allowing a larger volume of water to exist away from the shear zone while will allow a greater volume to flow while not being in a state of shear and thus lowering the friction inside the pipe.

Steve

Invigor
10-09-2004, 05:02 PM
so I assume using the "shear" theory, that is why mag drives recommend you double the pipe size compared to the pump input/output? (ex: my mag 12 has 3/4" inlet/outlet so I should be using 1.5" pipe to maximize the water flow?)

I guess with less pressure my mag would be quieter too! :eek:

Aquattro
10-09-2004, 05:53 PM
If anyone's interested, the following book is invaluable for this topic of fluid dynamics.

http://www.amazon.com/exec/obidos/ASIN/0130973254/qid=1097344324/sr=2-1/ref=pd_ka_2_1/104-9660101-0323124

StirCrazy
10-09-2004, 07:48 PM
so I assume using the "shear" theory, that is why mag drives recommend you double the pipe size compared to the pump input/output? (ex: my mag 12 has 3/4" inlet/outlet so I should be using 1.5" pipe to maximize the water flow?)

I guess with less pressure my mag would be quieter too! :eek:

this is part of it but you are also incorporating laminar and turbulent flow to the equation.

now this is just off the top of my head so if I have some terms wrong for give me.

OK one assumption to make, the law of conservation of mass (meaning a given mass put in in a period of time must come out in the same period of time)

if you have a small pipe it will cause high shear stresses which will lead to turbulent flow. this is because if you look at the conservation of mass you are putting in 200 gph from a 3/4" pump outlet into a 1/2" line so the result will be a increase in pressure so it can keep the same volume of water coming out the end. this increase in pressure makes the pump work harder but it also reduces the efficiency of the pump by making it have to work harder to achieve the same result. inside the pipe as the amount of water put in increases you fine the shear stresses between the boundary layer and the rest of the water increase until the water flow becomes turbulent and requires even more work out of the pump to push the water through.

by going to a larger pipe you are slowing down the water flow and creating a laminar flow of water through the pipe. you are also dropping the back pressure allowing the pump to work more efficiently.

Steve