Underwater air piping/air bubbles

[Flyboy10]

Hi all. I'm trying to design a system to release a series of air bubbles along a hose at the bottom of a pool. The pool depth is 4 foot and the lenght is 75 foot.
I have found 1/2"dia weighted, perforated airhose, but an associate says that a larger hose will require a much cheaper (lower pressure)pump. Is he all wet?
This is not my field, so any references as well as any plug n'chug, will be very helpful. Thanks

 

[pardal]

Please give more data about the task to do.

The first is that the blower shall have a static pressure more than 4 foot water column plus the resistance from the pipe and the holes.
To do a regular flow the pipe shall be on at least 4 loop

Pardal

 

[grimma]

sorry, not an answer, but a question for pradal:
How do you calculate the resistance of the holes???

grimma
d.ranslant@europe-environnement.com

 

[stressriser]

Flyboy,

He is kinda right.
The pump has two ratings.
Flow, as in Cubic Feet per Minute. (CFM)
Pressure, as in Pounds per Sq. inch. (psi)

You need to be just as concerned with flow as pressure depending on how you want your bubbles to "look".

You need to push out all the water in the tube. The water depth is 4 feet so you need to push it down with around 2 psi (1.76) just to move the water. There is a pressure drop in the system that will need to be overcome with more pressure. This is because of friction and viscosity. There are tables that you can use to avoid all the Reynolds calculations and such. You will need to know the flow rate which means you will have to convert your CFM from the pump into GPM and then find the pressure loss. This also will depend on the material of the pipe.

Example, smooth pipe 2 gpm (min recommended) in 1/2-inch diameter pipe has a pressure drop of 57.2 feet per 100 foot of length.. Compare this to 8 feet of loss for a 3/4-inch diameter tube.

The pressure drop is less for large diameter tubes, so your friend is right. But, more volume of water in the larger pipe is harder to push out with air unless you have a large Flow rate (CFM). Otherwise, the air will bubble past the water or go over the top of the water and not push it all out...this might not be a problem. Larger CFM pumps also cost more. There is also a burst pressure rating on the tubing, but you are only talking about 10 psi or so.

I use 35psi and 25 CFM to blow the water out of my sprinkler system.

I'd be interested to know what you are doing, there are other things to consider.

 

[pardal]

I use a Handbook from a Air compresor Manufacturer edited in Venezuela.
Whose authors are:
Arturo Abuchaibe, Eng
Eduardo Rodriguez, Eng
Ricardo Timperi, Eng
Nicola Morena, Eng
Gabbriel Sanchez Tech.

It has al data for this pourpose.
k281969@hotmail.com
Pardal

 

[butelja]

One small but important detail. Place your holes on the BOTTOM side of the pipe, or in 2 rows slightly offset from the bottom centerline. If they are not on the bottom, you will likely be unable to push all of the water out of the sparger, and flow distribution will be affected (not in a good way). The reason for using 2 rows near the bottom rather than 1 row on the bottom is for increased uniformity of bubble flow on both sides of the pipe.