Gutter calculator

[moemen83]

Hi guys,

I'm an Architect. I have a raised overflow pool in my project with approximately 200,000 gallons of water. Yes, it's massive.
We need to make our pool looks as if it's floating. So we're working on hiding the gratings to be a minimal slot hidden under the pool's stone edge.

The question is how we can calculate the gutter size hidden under the stone finish deck? We're afraid that while the pool is splashing with huge amount of water _since too many users will be using it_ that the gutter won't be sufficient and the water might come out again out of the drain slot.

 

[danjaymor]

You can calculate gutter flow rate the same as if you were using pipe.

This link has a nice calculator for estimating: http://www.1728.org/flowrate.htm

Your biggest challenge will probably be applying an estimated number as to how much spillover at peak times you will be getting......

 

[Zadd]

Isn't there a reserve tank for over flow pools to hold execss water when bather load is high and water is displaced? When bather load is reduced the reserve lets water Back into the pool. I forget the technical term.

 

[mas985]

You can use the weir formula. That associates the depth of the water over edge with the length of weir to estimate flow rate. This is what is used for waterfalls. I have the formulas programmed into a tab of the Pool Tools spreadsheet located here:

hydraulics-101-have-you-lost-your-head-t915.html#p6544

Background:

http://www.engineeringtoolbox.com/weirs ... d_592.html

But keep in mind that the flow rate is dependent on the thickness of the water over the edge so it is basically an infinite range.

If you need to calculate the volume of the gutter, that is a different problem. The way I would approach it is to the average volume of body (~20 gallons) and assume maybe 10 people jump in the water at once (~200 gallons). So if you build the gutter to handle twice that or maybe 500 gallons (67 cu-ft), you should be fine.

How long is the gutter/edge?

 

[moemen83]

You can calculate gutter flow rate the same as if you were using pipe.

This link has a nice calculator for estimating: http://www.1728.org/flowrate.htm

Your biggest challenge will probably be applying an estimated number as to how much spillover at peak times you will be getting......

Thanks Danjay. But I guess it's a bit far as an estimation. I tried solving for a pipe diameter and I entered the perimeter of the pool as a velocity in feet/second, then I estimated the water flow rate as 500 gallons (67 cubic feet) as mas985 advised estimating that 10 persons jumped into water at the same time. The answer was almost 13cm.

I donno how much that is close to reality.

 

[moemen83]

Isn't there a reserve tank for over flow pools to hold execss water when bather load is high and water is displaced? When bather load is reduced the reserve lets water Back into the pool. I forget the technical term.

Yes Zadd, but I need to calculate the the gutter diameter/cross section before reaching the tank.

 

[moemen83]

You can use the weir formula. That associates the depth of the water over edge with the length of weir to estimate flow rate. This is what is used for waterfalls. I have the formulas programmed into a tab of the Pool Tools spreadsheet located here:

hydraulics-101-have-you-lost-your-head-t915.html#p6544

Background:

http://www.engineeringtoolbox.com/weirs ... d_592.html

But keep in mind that the flow rate is dependent on the thickness of the water over the edge so it is basically an infinite range.

If you need to calculate the volume of the gutter, that is a different problem. The way I would approach it is to the average volume of body (~20 gallons) and assume maybe 10 people jump in the water at once (~200 gallons). So if you build the gutter to handle twice that or maybe 500 gallons (67 cu-ft), you should be fine.

How long is the gutter/edge?

Thanks mas985. I guess what you meant to download is the pool pump tools going for waterfalls tab.
Forgive the dummy part of me. I have four inquiries. First, why there is four cells infront of each parameter. Second, is the 'Edge width' will be considered as the pool perimeter. Third, Is the edge depth meant to be the thickness of the ledge. Last, Shall I consider the height between the pool edge and the slot channel as the height above water line.
I guess this will give me the flow rate per minute/second.

I need to determine the volume of the gutter. So do you think that if estimated the number of people and applied the amount of the excess water occurred as the gutter volume capacity. do you think it can work in that way.


The pool perimeter is ~ 138m almost 460 feet.

 

[danjaymor]

Since you are going to be working with industry standard equipment sizing, these guys may be able to help you:

http://www.ndspro.com/drainage-systems/ ... y-overview

 

[mas985]

I need to determine the volume of the gutter. So do you think that if estimated the number of people and applied the amount of the excess water occurred as the gutter volume capacity. do you think it can work in that way.

If you are only interested in the gutter volume (depth), then there are a limited number of ways to determine that. I tried to think of a worst case for water displacement (10 people) and just used that as an estimate. 10 people is about 200 gallons and a trough that is 460 feet long needs to have an area of 9 square inches or 3"x3". So basically, if your trough is bigger than that, it shouldn't be an issue. They can't really make waves big enough. However, there could be over splash so you might make the trough wider than deep.

 

[moemen83]

Thank you guys. really appreciated

 

[Andrew69]

Isn't there a reserve tank for over flow pools to hold execss water when bather load is high and water is displaced? When bather load is reduced the reserve lets water Back into the pool. I forget the technical term.

Yes Zadd, but I need to calculate the the gutter diameter/cross section before reaching the tank.

Ive had the same problem for my new pool - same deal as you, hidden gutter but Ive sorted the gutter issue by planning to build shorter "lengths" of gutter, leading to "droppers" (4" dia) dropping into a 6" pipe with 1:100 fall.

Pool builder has extensive experience in design and construction of large commercial pools and he says I should strongly consider using 8" dia pipe as he thinks the 6" wont be enough.
Having said that, I think he was taking about 1, 8" dia pipe that travels around the entire perimeter of the pool (25m lap pool) to the catch tank, while Im planning on running the 6" pipes from the center of the far side (equipment is mount under ground, at the mid-line of one side) around each side, so I have 2, 6" pipes in effect.