Science Question

[grouper therapy]

LilRobb;680357 wrote: So the table2 in Acroholic's link is wrong?

Edit:

That would be an F in school - good answer, but not for my question... LOL

it totally answers it

 

[lilrobb]

grouper therapy;680370 wrote: it totally answers it

That's like linking wikipedia - the answer is there, you just have to find it... LOL

 

[grouper therapy]

4' feet of 6" pipe attached to a mag 5 vertically will produce more gph than 4' of 3/4" in the same scenario.

Edit: Now the velocity that it exits the smaller pipe may be greater but the flow(gph) will be reduced

 

[morganatlanta]

LilRobb;680230 wrote: So let's say I have a 1/2 pipe standing upright and a maxijet on the bottom - I can determine the max head pretty easy by measuring the height of the watercolumn in the pipe.

What happens when I use 4" pipe now, will the pump reach the same head height, more or less?

(my point of view - where I differ from a dear friend is the following:

The water column in a 1/4" pipe has a weight of x lbs pressing down on the pump, a pipe with 4" diameter has significantly more water (weight wise) to carry so the back pressure on the pump will be more, hence it will reach less head height,)

Scientifically proven comments?

Yes, because at the max height, the flow is 0, so the friction due to moving water is 0, so the only thing to consider is the head pressure.

For situations where you have flow of a certain amount you want to achieve and are trying to figure out if your pump will do it, you can do "equivalent pipe length method".

Basically, based on the flow you want and the pipe size and various fittings, you calculate (look up in the tables and add up) the corresponding head loss from friction caused by the plumbing (at that flow rate). The you check the total head loss versus flow chart for your pump and see if you can get the flow you want from the pump and plumbing you've got. If not, you change the pump, or the size of the plumbing, and see if that gives you the flow you want.

Iterate until you get an answer you like, but then you still don't know because the capacities of the pumps are always over rated. So you guess and buy a bigger pump than you need and try it out then sell it here if it doesn't work out.

 

[grouper therapy]

Robb ,Based on your theory you could not fill a 4' deep pond with a garden hose lying in the middle on the bottom

Edit:

blixem;680379 wrote: Wouldn't this only be under the assumption that the outlet of your mag5 is 6" not using a collar to go from 3/4" to 6"?

no

 

[lilrobb]

grouper therapy;680381 wrote: Based on your theory you could not fill a pond with a garden hose lying in the middle on the bottom

Great example, but it neglects the force of the pump on the other end, using a maxijet, i would agree - using an ampmaster - it would differ

 

[acroholic]

LilRobb;680351 wrote: Acroholic is next, and his table reference looks pretty good to me...

Edit:

Okay,

so that means at a certain height flow would be ZERO, correct?

I didn't take credit for anything, just provided a reference that looked somewhat understandable!!!

 

[grouper therapy]

LilRobb;680383 wrote: Great example, but it neglects the force of the pump on the other end, using a maxijet, i would agree - using an ampmaster - it would differ

it is all relative to the max head of the pump. If a maxijet has the ability to overcome 4" of total dynamic head then it will fill the pond.It would fill Allatoona if it were no more than 4'deep(baring evaporation)

 

[lilrobb]

Dave,

you and me and my maxijet against a 7' 2" pipe tomorrow!

 

[sharkbait]

grouper therapy;680343 wrote: Wrong

Yes, please prove that a 4'x4" section filled with water weighs the same as a 4'x1/2" section......WRONG!

 

[grouper therapy]

LilRobb;680389 wrote: Dave,

you and me and my maxijet against a 7' 2" pipe tomorrow!

I'll call your 2"and bring a 12" diameter.which brings me to my next example skimmers.If a large diameter tube dictated head loss some of the skimmers I've seen would be rendered useless

 

[lilrobb]

Sharkbait;680395 wrote: Yes, please prove that a 4'x4" section filled with water weighs the same as a 4'x1/2" section......WRONG!

On that issue I may side with Dave, the weight is different, but the pressure/weight by square inch is the same...

 

[crew]

blixem;680388 wrote: Apologies all, my first response was wrong. Depth/Head pressure is the same no matter the diameter. I somehow read it and got completely turned around.

That being said, I still believe there is a point where on an outlet you can make the pipe too big and cause recirculation within the pipe.

You wouldn't cause re circulation because the inlet isn't inside the pipe.

 

[sharkbait]

LilRobb;680398 wrote: On that issue I may side with Dave, the weight is different, but the pressure/weight by square inch is the same...

Rob, then just hook it up and see if your right then.

 

[grouper therapy]

ok let me try it this way take the same diver measure the pressure exerted on that diver at 100' in lake michigan and measure the pressure exerted on him in lake Lanier at 100' and tell me the difference,

Edit:

Sharkbait;680395 wrote: Yes, please prove that a 4'x4" section filled with water weighs the same as a 4'x1/2" section......WRONG!

Don't need to that is not the question! It is ok to just listen sometimes.

 

[sharkbait]

grouper therapy;680401 wrote: ok let me try it this way take the same diver measure the pressure exerted on that diver at 100' in lake michigan and measure the pressure exerted on him in lake Lanier at 100' and tell me the difference,

You didn't dictate whether my entire statement was wrong or a particular part was. Therefore your saying I was wrong on the weight being wrong would mean that you are wrong.

Edit:

LilRobb;680230 wrote: So let's say I have a 1/2 pipe standing upright and a maxijet on the bottom - I can determine the max head pretty easy by measuring the height of the watercolumn in the pipe.

What happens when I use 4" pipe now, will the pump reach the same head height, more or less?

(my point of view - where I differ from a dear friend is the following:

The water column in a 1/4" pipe has a weight of x lbs pressing down on the pump, a pipe with 4" diameter has significantly more water (weight wise) to carry so the back pressure on the pump will be more, hence it will reach less head height,)

Scientifically proven comments?

hmmm....

 

[grouper therapy]

Sharkbait;680231 wrote: You are correct Rob, the larger the diameter of the pipe the more weight/head pressure. So if you were to use the maxi-jet on the 4" pipe you would get significantly less height then with the 1/2" pipe. Most pumps have a pipe total diameter size on them to indicate for this very reason.

All of this is wrong .sorry You phrased weight with head pressure is why I again say wrong. It is ok to be wrong .

 

[sharkbait]

grouper therapy;680404 wrote:
All of this is wrong .sorry You phrased weight with head pressure is why I again say wrong. It is ok to be wrong .

Whatever you think....

 

[grouper therapy]

Sharkbait;680408 wrote: Whatever you think....

That was convincing:lol2::lol2::lol2:

 

[sharkbait]

grouper therapy;680416 wrote: That was convincing:lol2::lol2::lol2:

Not going to try and convince you. You have your ways and I have mine. Simple as that.