chimera Posted November 3, 2004 Report Share Posted November 3, 2004 of course, there has to be a maximum pipe size where flow starts to deminish. the greater the diameter output pipe, the more water in it hence the more weight in it pushing back against the return pump. i still dont see how a larger diameter return pipe (than the pump outlet diameter) is going to improve performance. also, what diameter inlet to your sea-swirls? Quote Link to comment Share on other sites More sharing options...
Pies Posted November 3, 2004 Author Report Share Posted November 3, 2004 the more water in it hence the more weight in it pushing back against the return pump Thats incorrect, it does't matter how big the container is the pressure is the same based on the height. The pressure at the bottom of a swimming pool at 10m is the same regardless of if the swimming pool is 5m wide or 50m wide, height is the only factor, not volume. i still dont see how a larger diameter return pipe (than the pump outlet diameter) is going to improve performance. Less friction. Like I said, the people who I spoke to, who do water flow technology for a business reccomended this to me. Maybee they are wrong? I happen to belive them and its consistant with what I have read. Inlet for the seaswirl 20mm. Pies Quote Link to comment Share on other sites More sharing options...
suphew Posted November 3, 2004 Report Share Posted November 3, 2004 I'm no expert either but the guy I talked to is, he's certified high pressure boiler engineer, certified mad to. As I understand it you are correct going smaller to larger does reduce fiction/increase flow, BUT at some stage you have to go back down smaller again, this is where the problem is, it takes so much energy to put the water back into the smaller hole that you lose all that you have gained, esp once you add in turbulance etc that is created. Another point to remember is that the fiction of straight hose is pretty low, making the water fight gravity and go around bends has a far greater affect. Quote Link to comment Share on other sites More sharing options...
Pies Posted November 3, 2004 Author Report Share Posted November 3, 2004 Suphew - Yeah I suspect your right. However points to remember is the number of elbows/bends will be static regardless of the pipe size. What you are saying about squeezing the water through the smaller holes makes sense. I was planing on using 32mm to 2x 20mm. The 20mm is fixedm as is the 25mm outlet of the pump. So I guess the question is this: 1. Should I use 25mm, 32mm for the return pipe (currently I think 32mm is better but I am prepared to listen so some science) 2. Should I use a single elbow and tap of both 20mm outlets or use the T/Y soultion? I will present this with pictures. The sonner I get an answer, the sooner I can drill a hole through the floor. Pie Quote Link to comment Share on other sites More sharing options...
chimera Posted November 3, 2004 Report Share Posted November 3, 2004 i'll add my own question to your post if I may! i want to go from 25mm outlet on iwaki to sea-swirl but the sea-swirl inlet is 20mm. will replacing the current 20mm pressure piping to 25mm pressure piping then reducing just before the sea-swirl (@ 20mm) improve performance? from what is written above it wont? i think i need to read more on water dynamics!!! :lol: Quote Link to comment Share on other sites More sharing options...
Pies Posted November 3, 2004 Author Report Share Posted November 3, 2004 From what I understand it will, as the flow will be less impeeded by the larger bore on the pipe, pressure will be uneffected based on the head pressure so all you will be doing is allowing more water to flow through. I am in the same boat, 25mm (pump) to 20mm Sea Swirl. But I have to feed 2x Swa Swirls. so does that mean I should feed the 2x 20mm feeds from a 40mm pipe to give me maximum flow, or would 50mm be better (an extra 5mm per sea swirl?). Its worth sorting it out now, I refuse to make a mistake and drill 2 holes through the floor or just waste money repurchasing plumbing, over and again. Pie Quote Link to comment Share on other sites More sharing options...
chimera Posted November 3, 2004 Report Share Posted November 3, 2004 luckily i can use the 20mm pressure piping replacing the cheap 19mm irrigation piping for the closed loops :lol: Quote Link to comment Share on other sites More sharing options...
Ira Posted November 3, 2004 Report Share Posted November 3, 2004 I don't think you'd find too much of a flow difference between using 40mm feeding the sea swirls compared to a 50mm. The two sea swirls would still be the biggest restriction. Even the 2X20 is only 2500ish mm^2 area compared to the 40mm being 5000 mm^2, the 50mm at 7850 mm^2. So, uhh, my point is that you're worrying about making the already least restrictive part less restrictive, you should think about making the most restrictive less restrictive. But, you can only do that by using bigger sea swirls, but you're not going to really make any difference anywhere else. I say throw it all together the way you've got it and call it good. With large radius elbows and all that you're not going to be able to squeeze more than a tiny bit of extra flow out of it. Put your time and money into some other component. Quote Link to comment Share on other sites More sharing options...
chimera Posted November 3, 2004 Report Share Posted November 3, 2004 Thats incorrect, it does't matter how big the container is the pressure is the same based on the height. The pressure at the bottom of a swimming pool at 10m is the same regardless of if the swimming pool is 5m wide or 50m wide, height is the only factor, not volume (not saying you're right or wrong) This would be valid for a swimming pool but not necessarily your or my setup. At any point at the bottom of the pool the force is effected by the height of the water directly above it. With the pump however, the water above (say a 32mm pipe) is being squeezed back into a 25mm opening (the iwaki outlet) the water has to go somewhere, that force must be applied to the outlet, cant go anywhere else. Surely (for arguments sake) a 2 metre pipe above a 25mm opening will be greater pressure at that opening because of the greater water volume? If it were a 2 metre outlet, then it wouldnt matter. Im saying this by what seems logical - not sure if its a valid theory or not though?!!! Quote Link to comment Share on other sites More sharing options...
Pies Posted November 3, 2004 Author Report Share Posted November 3, 2004 Im saying this by what seems logical What seems logical for you, you mean Think about this: Head pressure, if the width of the pipe made a difference, then the head of a pump would be effected by the size of the outlet. Eg based on your theory a pump would pump less if say it was pumping up a 25mm hole than a 40 mm hole as it would weight more/provide more pressure, which isn't the case. Notice how the head pump factor charts don't compensate for this? Its because they don't have no, pressure is consistant. Also based on that theory, a pump submerged at 200mm under water in a 2 foot tank would pump more water around than if it was submerged at 200mm in a 4 foot tank because of the less weight/pressure, which is not the case. Pies Quote Link to comment Share on other sites More sharing options...
Brianemone Posted November 3, 2004 Report Share Posted November 3, 2004 what if the outlet is only 1mm?? wouldnt that increase the pressure??? Quote Link to comment Share on other sites More sharing options...
RnB Posted November 3, 2004 Report Share Posted November 3, 2004 imagine how hard diving would be... the sea stretches for thousands of miles... the pressure at 10m might kill you :lol: :lol: :lol: or if you swam into a pointy cave on the sea bottom ouch...... :oops: Quote Link to comment Share on other sites More sharing options...
suphew Posted November 3, 2004 Report Share Posted November 3, 2004 Pie's my mate is going to be at my place on Tuesday if you want to come round and have a chat to him. If you have the time I think it would be well worth the effort esp as going from 1x25mm to 2x20mm adds a whole ton (or is that tonne!!) of extra factors!! Just a few of other things for every one, 1) when thinking about pipe "size" going from say 20mm to 40mm is double the diameter BUT many times the area (volume) so to put twice the amount of water through a pipe doesn't mean going to twice the size pipe, far from it in fact. 2) don't confuse head of water (which is constant no matter the volume) with weight of water (increases with volume). 3) friction is really hard to get your head around and isnt as simple as bigger pipe = less friction, the friction between two surface's is constant when going to a bigger pipe you are increasing the surface area of the inside of the pipe therefore the friction increases! But if your pump can do it you are also increasing the volume of water in the pipe so the ratio of water to (friction causing) surface area increases (or is that decreases??) giving less friction, hmmmmmm confused, I am! After all these years I finally found a use for all the physics study! Craig Quote Link to comment Share on other sites More sharing options...
Pies Posted November 3, 2004 Author Report Share Posted November 3, 2004 1) when thinking about pipe "size" going from say 20mm to 40mm is double the diameter BUT many times the area (volume) so to put twice the amount of water through a pipe doesn't mean going to twice the size pipe, far from it in fact. 2) don't confuse head of water (which is constant no matter the volume) with weight of water (increases with volume). 3) friction is really hard to get your head around and isnt as simple as bigger pipe = less friction, the friction between two surface's is constant when going to a bigger pipe you are increasing the surface area of the inside of the pipe therefore the friction increases! But if your pump can do it you are also increasing the volume of water in the pipe so the ratio of water to (friction causing) surface area increases (or is that decreases??) giving less friction, hmmmmmm confused, I am! Craig 1. Quite right, no dispute from me on that. 2. No doubt that the as volume of water increases, the weight increases, but that doesn't actually effect the head pressure. Head is consistant. Doesn't matter if I have a hole in the bottom of a bath or a swimming pool, the flow rate of the pump will be consistant given the head (height) of water, the amount of water in the tank doesn't make a difference. If you fill a swimming pool to 1 M deep, and a 44 gallon drum to 1m deep, drill a 25mm hole in the bottom of both and open it, the flow rate will be the same at any given heigh (once the both empty to .5m the flow through each will be identical). Of course it will take longer for the larger volume of water to empty. 3. As the surface area increases with the larger pipe, then of course friction increases. However because the pump is more or less a consistant, the effect of friction on a larger pipe is less than on a smaller pipe as the water flow is less 'forced' accross the surface. I am going to go out today and get some math from the people I have spoken too, so they can prove to me that they know what they are talking about. If they do, i'll post the math here for you to all pick apart. Craig - Tuesday is a bad dayfor me, as its survivor night. But if I can pop over before or after survivor then i'd love to chat with him I'll bring pictures Pie Quote Link to comment Share on other sites More sharing options...
suphew Posted November 4, 2004 Report Share Posted November 4, 2004 Haha surviver night aye!! Ben will be at my place from 5ish, I'll be home at 6ish, we normaly pack up around 9-9:30, just let me know, txt or ring on tuesday if you like. I hope you succeed getting the math sorted, I would be nice to have all the foruma's and rules posted so we can all work it out with out having to remember physic's lessions from 15 odd years ago!! Quote Link to comment Share on other sites More sharing options...
cees Posted November 4, 2004 Report Share Posted November 4, 2004 probably heaps of sites to be found. perhaps this one has all the math ? http://www.mcnallyinstitute.com/07-html/7-01.html Quote Link to comment Share on other sites More sharing options...
chimera Posted November 4, 2004 Report Share Posted November 4, 2004 imagine how hard diving would be... the sea stretches for thousands of miles... the pressure at 10m might kill you RnB - I meant picture it like a funnel, the water is leaving the bottom part of the funnel and you are sitting in the middle of it. the pressure is directed into the hole, not all the ocean around you so diving is a poor comparison. Even so, Pies is right, the water will only leave at a certain rate given its diameter. Anyways, the appropriate diameter of the pipe is directly related to the flow rate of the pump - no ones theory has mentioned this yet. The flow rate can be converted to velocity of fluid as follows: V = 0.4085 x GPM / D^2 Velocity = feet/sec GPM = Gallons per Min D = Inside diameter of pipe in inches From this we can see the first important observation about velocity and pipe diameter. Doubling the pipe diameter will decrease the velocity by a factor of 4 Frictional loss Hf = f x (L/D) x (V^2 / 2g) Where: Hf = friction loss in feet of head f = dimensionless friction factor L = Pipe Length in FEET D = Pipe Inside Diameter in FEET V = Flow Velocity in FEET PER SECOND g = Gravitational Constant = 32.2 feet per second squared From this equation it is quite clear that the flow velocity has a big impact on frictional losses. From equation 1 we know that the flow velocity is inversely proportional to the square of the pipe diameter. So if we reduce the pipe diameter by ½, we increase the flow velocity by a factor of 4 and hence also increase the friction loss by a factor of 16. ref: http://www.advancedaquarist.com/issues/jan2003/featurejp.htm I wish I found this article from day one! Pies - calculate the diameter using these equations to get the best results. You will probably find the 50mm pipe will perform much better than the 40mm (havent worked it out, just going by the theory on this site!) The issue I have is going from a 25mm pipe to a 20mm sea-swirl (restricted no matter what) So if I went 25mm out to a 32mm pipe then back to a 20mm, the restriction is with the sea-swirl. However under your setup, going 25mm out to a 50mm then back to 2 x 20mm sea-swirls is probably fine. Make sure you do the equation though. Play around til you get it right! Im not too fussed with mine, will probably increase pipe up to 25mm and be done with it. To save all the hassle, click this link (make sure you have macro's enabled) You can even select the Iwaki pump you are using! http://www.advancedaquarist.com/issues/jan2003/waterpipe-v1.xls Quote Link to comment Share on other sites More sharing options...
chimera Posted November 4, 2004 Report Share Posted November 4, 2004 oh, and... One problem is thinking that if the pump you are using has a ¾†or 1†inlet or outlet that is the size of plumbing that should be used. Another common misconception that many people have is that 90 degree elbows create an extreme amount of head loss. I’ve heard several people mistakenly quote that you need to count one foot of head loss for every 90 degree elbow in your plumbing setup. The wonderful thing about using these calculations is that you can easily compute the differences in flow under different designs ...I'll admit to falling into that trap. I calculated for my setup that going from 20mm to 25mm piping up will increase flow by about 150gph. However (as above) this is restricted because it has to reduce to 20mm again into the sea-swirl. So, what would the effect be if I increased the return to say 32mm or 40mm then T'd (or rather Y'd) off the return pipe near the tank into a 20mm for the sea-swirl and say a 20mm into another area of the tank? (much like Pies is doing except no 2nd sea-swirl for me ) Quote Link to comment Share on other sites More sharing options...
Pies Posted November 4, 2004 Author Report Share Posted November 4, 2004 Ahem. So it appears my water flow expert friends in the Hutt are right? Let me know when its safe for me to say 'I told you so'. Pies Quote Link to comment Share on other sites More sharing options...
Pies Posted November 4, 2004 Author Report Share Posted November 4, 2004 Chimera - Something else to consider, and part of my own consideration process. Once you get to 32mm and greater, you can buy PVC down pipe, as opposed to PVC pressure pipe. Its about 1/5 the price, so I hope to not only increase the flow of my pump by using the correct plumbing, but also reduce the cost. Not often the cheaper option is better Pie Quote Link to comment Share on other sites More sharing options...
chimera Posted November 4, 2004 Report Share Posted November 4, 2004 Let me know when its safe for me to say 'I told you so'. alrightly, off you go then i never said at any point that i was right, i simply put a different line on it to get some discussion going and have my opinions proved otherwise. as was posted earlier, one persons logic is different than anothers! oh, and no problem for the link, anytime, dont mention it... :lol: Quote Link to comment Share on other sites More sharing options...
Pies Posted November 4, 2004 Author Report Share Posted November 4, 2004 I told you so. And at the risk of being an arse: i never said at any point that i was right, i simply put a different line on it to get some discussion going and have my opinions proved otherwise The correct response would be "Your right, I fuxored up, sorry my bad" To continue the risk of being an arse: oh, and no problem for the link, anytime, dont mention it... ? How about "Hey, thanks for making me find some facts about what I didn't understand but thought I did". You see I didn't need the link, I have already done my research. Not to say its not useful (I will read it when I get a machine with Excel on it), but all it does is prove something that I have already researched. And seriously now, do you still belive this to be true? RnB - I meant picture it like a funnel, the water is leaving the bottom part of the funnel and you are sitting in the middle of it. the pressure is directed into the hole, not all the ocean around you so diving is a poor comparison. Even so, Pies is right, the water will only leave at a certain rate given its diameter. In one paragraph you say 2 different things! Do you still think the pressue at the bottom of the funnel is any greater? Hahahaha cracks me up. What if it was a really big funnel? Hahahahahaahahahaahahaha. *stop* Sorry Chimera, while I am picking on you at least I am leaving someone else alone. Friends? *Manly nod* Now lets get this thread back on track. If your all nice, I will treat you to some pics of my Durso and overflows tommorow (which are all finished and looking AWESOME), just need to glue em in. PieARSEman Quote Link to comment Share on other sites More sharing options...
chimera Posted November 4, 2004 Report Share Posted November 4, 2004 Thanks Piearse To elaborate: In one paragraph you say 2 different things! Do you still think the pressue at the bottom of the funnel is any greater? Hahahaha cracks me up. What if it was a really big funnel? Hahahahahaahahahaahahaha. *stop* When i first thought this theory to be the case, RnB came up with the diver story. My theory on that was the water above is all around him, not directed ontop of him like if he were in the bottom of a funnel. I took the liberty of justifying my theory that was wrong in the first place!!! You see I didn't need the link, I have already done my research so why the original question? Believe me, you will LOVE the link. Best link I've found ever to do with plumbing! I will do my research/reading first in future Quote Link to comment Share on other sites More sharing options...
Pies Posted November 4, 2004 Author Report Share Posted November 4, 2004 Not really wanting to continue the stupidy, but: so why the original question? I never asked a question, this all started from: Return plumbing is the last piece of the 'puzzle' I need to source. I have decided to use 32mm PVC for this to feed the 2 sea swirls. In the name of better water flow and tidy plumbing I will bring it in from one end and not use a T joint. Which then started you off along these lines: from what i've read, outlet piping should not be larger than the pump outlet (depending on application of course, but valid in this case). eg: 25mm outlet on the iwaki, use maximum 25mm pipe. as above, to do with turbulence and the likes. you need to maintain some form of pressure in the return pipe. Comprendae? PieMAN Quote Link to comment Share on other sites More sharing options...
chimera Posted November 4, 2004 Report Share Posted November 4, 2004 should really have started a new post for it, it's eating into your 'new tank setup' posts. Quote Link to comment Share on other sites More sharing options...
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