Head Loss ???

[raymond4133]

Okay I have been still thinking about this pump issue....I guess to make things a little visual I did a fast drawing on microsoft painting of roughly what my setup will look like or what I want it to look like...

The specs are:

-it's 4 feet high and there is 2 feet horizontal on each side for a total of 4 for horizontal feet...

-There will be three t-ee's (although would the tee's count as two elbows for each t-ee or is count as one...If it count as two per tee than there would be 6 elbows in the system...

-one ball valve just in case there is to much flow...

-3/4" flexible hose/pvc
-4 exits

-need no more than 1200gph total...

-So if i were to calculate this into head loss calclutor on RC home page would it calculate the amount of flow for one exit or is it going to calculate the flow for all four exits and I just divide that number by 4 and hope it adds up to 1200gph...

-So far I think the MAG 18 will do the job but I may have to consider the MAg 2400...

Iam so sorry to ask so many questions but I want to do this the right way...

Thanks everyone for input...

 

[CaliforniaDreamer]

If you run the Head calculator you will notice that it does more than a single iteration (calculation) to determine total head. The reason it does this is because calculating the head is somewhat complicated. It is very dependent on the velocity of the water flow in the system and through each length of pipe, Tee, Elbow, and anything else that can cause friction in the flow. The way it works is to do an initial calculation and estimate the flow through the system. From that it determines the total flow and from that the velocity of the flow. From that velocity it can now determine a better estimate of the total head. From that better total head it can determine the flow and again determine the velocity of the flow and get a new more accurate value for the total head. The program continues to do this until the changes from one iteration to the next becomes so small as to not matter anymore and the program is finished.

Because you are trying to calculate the head on a more complex system than the program is designed for your best approach is to try to error on the safe side. If I understand your concern you would like to get as close to 1200 GPH as possible. In my humble opinion I would shoot for a figure somewhat less, more like a maximum of 1000 GPH as being more than enough through the sump (my assumption is that these are two megaflows with a rating of 600 GPH each). It would also take into account reduced flows through the overflows as they are restricted by buildup of “stuff” as the tank matures, snails find the overflow, or whatever. In any case from looking at your drawing the use of 3/4 inch pipe will have a major effect on the flow. As you try to push more water through 3/4 inches you will increase the velocity and likewise increase the head.

I guess I would ask two questions. Why 3/4 inch pipe and why 1200 GPH. In any case good luck with your endeavor.

 

[raymond4133]

Thankyou so much CaliforniaDreamer for helping me on my way...

Well I want to use 3/4" because that is what I already have...

And the hole on my tank is not a 1 inch hole so I can't really use a 1 inch return.... rather there is only a 1 inch hole for the 1 inch durso pipe that brings water to the sump...

And 1200gph...Just because I had the notion of maximizing my megaflow overflows to it's full potential...But, you might advise other wise...

-Iam fell so frustrated in trying to pick the right pump and all...And these pumps are not so cheap...(Well nothing in this hobby is cheap) but, hey what Iam going to do...

-I also just thought about it today to put 4 exits so that I have a little bit mor flow in and around dead spots in my tank...Two on each megaflow overflow...(So iam guessing I would have about 300 something gallons coming out of each of the 4 exits...

-Regardless It's get a Mag 18 or perhaps a 24 to even expand my possibilites but I think the MAG 18 might by suited for this job...(what do you think) of pushing about 1200 gph into my tank with the amount of head pressure...

-Actually I feel so sick and tired of looking for the right pump, pressure,etc, quiet or not, dependable or not, etc. that I am going crazy(as indicated with the rolling smilie face)

:rollface:

I am so sorry to ask so much questions, but just as anyone frustrated with a hobby I would very much love to solve the problem...And I think by getting a ball park estimate I can achieve that...HMMM???

 

[dots]

I think it cool that you are asking so many.......just means in the end your design will work because all of the research and thinking you have put into it.

I had pulled out my fluids book to do it by hand for you and saw that it didn't have charts for small dia PVC because it focuses on big mongo systems......So I went on a search for a chart that would give you the minor losses you needed for EXACTLY the fittings you want to use, rather than say 2-90s=1-tee, to provide you with the "exact" numbers.

Look what popped up on the Google, imagine that.........a very well and complete article from none other than........ It explains all the technical hows and wheres, and even a chart with ALL the fittings, because I was only finding the common charts, not ones with your ball valves.......So read up, calc up your numbers by hand and then you will really appreciate that online calc, and should give you all the answers you should need......one word of advice, careful on your units, or use the Excel spreadsheet.

I think I will bookmark this one myself for reference.....

http://www.advancedaquarist.com/issues/jan2003/featurejp.htm

And yes, the resisantance will increase as you try to push more gph through and your pump effieceny will go down......(flow in = flow out), thats why we took the limiting factor of 1 drain to be 600gph, hence each branch to be a max of 600gph......the only spot it will be around 1200gph is near the outlet of the pump before it branches, where it should be one inch and tee off to 3/4 if you need it to go into the display. Adding another tee, we could expect a maximum of 300gph at the nozzles which the 3/4" can handle........This is a theoretical maximum, it will be even less because of our efficiencies and minor losses. If you want a tank with rip roaring flow, you will probably have to add another closed loop circuit. Or increase the gph and get bigger dia pipe.

Yes, bigger tanks cost more to set up and stock, but are generally more stable and have a higher degree of success than smaller, that is where you money spent will pay off.

Its all good.......next time you'll be answering the questions because you took the time to figure it out for yourself......:thumbsup: :thumbsup:

 

[CaliforniaDreamer]

http://www.advancedaquarist.com/issues/jan2003/featurejp.htm

sacramentodots great reference. I'm going to bookmark that one too. :thumbsup:

 

[dots]

Those charts for the minor losses of fittings are so money!!! Plus its cool to be able to have one place to reference from, because as you can see the Darcy way of calculation can be a little convoluted and thats the way we were taught how to do it.