45 vs 90 PVC bend?

[androal]

Stupid Question?

I noticed that the RFC head loss calculator considers the same resistance for for 2x 45 bends as it does for 1x 90 bend - seems logical, but thought I would ask those who "know" ?

Do the two configurations reduce flow identically?

Is there any reason to substitute 2x 45 vs. 1 x 90?

http://reefcentral.com/gallery/data/500/182438pvc.jpg

[Soundwave]

It may be true that two 45s will reduce flow as much as a 90 but most people will use two 45s spaced farther apart than two 90s to get to the same place.

HTH

[Am4nn]

Might as well use 45s if you have the room, plus fittings are inexpensive enough not to matter.

[Devil Man]

and if your not happy with the out come of the flow then put a bigger pump on there and be done.

[tundra1000]

Not really a stupid question, I was actually wondering the same thing. It seems to me that if you were trying to get the most out of a pump running the lines with as gradual direction transitions as possible would help flow. The larger the radius of the curve the less velocity would be lost. But 45's I guess are different than a large radius. Where are the fluid dynamics engineers?

[tundra1000]

Just found this in another thread, great tool. Shows a slight difference between 1 90 vs 2 45 but not much. Check out this tool-
http://code.google.com/p/plumbingpy/

[Devil Man]

this has been talked about on here alot before... the most effeiecnt is to use a sweep 90... which mimics alot of 2 45's. do a search and i am sure that you would have found your answer... thats why this site is so clogged up....

[kcress]

Two 45 are waaaaaay less restrictive than a close 90! That isn't correct on the calculator then (unless!!) the flow is far below the typical flow expected for that size fitting.

You can see that if the water was moving 1/2 foot per minute a close 90 would not be much more restriction than 4 inches of straight pipe. But if the water is moving 10 feet a second that 90 is way more restrictive. So if the numbers you give the calculator are way down the flow rate then you would see little or no variation between the 45s and the 90.

Step up the flow by 20X and see if the two change dramatically.

[androal]

Thx Kcress, that is the correct answer! Thx for taking the time to respond. I hope the server will somehow recover from the lethal blow I dealt it by posting this question!

do a search and i am sure that you would have found your answer... thats why this site is so clogged up....

I love the FL real estate sales guys precise and accurate technological explanation for RC's website performance issues.

Your brilliant Devil Man - you go guy - I agree! It is, in fact, my fault!

It never ceases to amaze me how some people actually find it more rewarding to take the time (and bandwidth) to put down the newbie instead of just answering such a simple question!!!??? Maybe it's just reflective of the current FL real estate market. My condolences Devil Man. The feds got your back buddy!

But seriously, it is truly impressive how many threads around here ultimately are answered by basic fluid dynamics 101 type responses.

For some reason gravity and friction is just kinda hard for some of us less-gifted people to immediately grasp intuitively!

BTW Devil Man, I DID hunt for this a bit before posting, and it was amazing how many conflicting opinions get posted on topics that are actually straight-up, undisputable scientific facts.

Maybe there is an opportunity for a "Fluid Dynamics 101" thread to clear up the basics so all us Newbie's don't have to keep regurgitating the same Q&A...?

Do a search for overflow siphons. I just built mine based on feedback from this forum -and as a result - they work great! These were certainly not "obvious" in their design - and it required sifting through 100s of different answers to seemingly the same set of questions. Lots of garbage and misinformation out there - and lots of great valuable stuff too!

I guess thats just the nature of DIY?

[androal]

the most effeiecnt is to use a sweep 90...

... ok Devil Man, now that I had my fun ... your right!

Sweep 90 is the "bend-of-choice" for "those-who-know" the difference!


http://reefcentral.com/gallery/data/500/182438sweep90.jpg

as usual... the correct answer to the question is "none of the above"

A sweep 90 trumps BOTH a traditional 90 AND 2 x 45's

Why is this hobby so hard to get right the first time???!!!!

[androal]

I guess this is just further defense to the rationale that flexible tubing is superior to rigid PVC?

My personal view is that whatever HD and Lowes stock is what the world will go with!

Its a big bad capitalist world isn't it?

Pave the world! *@#! the rest! (ouch! that won't go over very well on a reef-friendly forum!)

[Devil Man]

haha.. your funny... just last week i belive it was that members talked about this. And they spoke of how the ridges inside of the flex piping would cause more friction then the ridged(smooth inside) would making the ridgid more effective at the end.

btw i would really looking into getting a PRESURE rated sweep rather then that 90 that you posted a pic there. cause for your info, that is DWV. i will leave you to search to try to find out what that means since you seem to know so much.

I didnt put down you becuse you where a noob, i did it cause this has been talked about countless times, as a mater of fact i think in the DIY section there is a thread similar to this going on right now. had you been someone that has been on here for years or just recent i would have said the samething to you. i do know that it is consuming more sever space but some might not understand that. these threads that have beaten with a dead horse are getting out of hand. reef central doing i dont know what to help this problem that we all encounter with the server being cloged up, we all need to try to work together to keep this site running as smooth as possible, and in doing so searching before asking is one.

also dont try to attack my profession or what i do. you come across really immature doing so. there are so many reasons why the market is the way it is now. One could be because of newbies trying to come here and get involed in the real estate market trying to make some quick money and doing things wrong or getting into loans that they couldnt even pay for after there 3 year arm was up, and the rate increased, that and so many more things, like fraud and i could keep on. next time keep those comments out of here.... and try to search a little harder before you start a thread.

[Devil Man]

Its a big bad capitalist world isn't it?

Pave the world! *@#! the rest! (ouch! that won't go over very well on a reef-friendly forum!) [/B]

i think that this quote and the attitude that you speak in and what you have for a occupation are kinda oxymoronic. i have gone and read your other post and see that you post in the same matter as you did here.

[androal]

My sincere apologies Devil Man.

The spirit that my comments were written were just to try keep things light hearted and fun.

I'm sure your not the only one who either doesn't understand or simply doesn't care for my sense of humor - I apologize.

I didn't mean start a flame here!

Hear any bad jokes about people from NJ lately? I always get a laugh out them! It's all just in good fun!

The worlds gotton so serious these days!!! I think it must be the economy's fault!

[androal]

i do know that it is consuming more sever space but some might not understand that. reef central doing i dont know what to help this problem that we all encounter with the server being cloged up, we all need to try to work together to keep this site running as smooth as possible

I'm honestly curious about this - I DO want to do my part to help keep the site running as smooth as possible.

When I first signed up - it was curious to me that RC wants users to pay in order to be able to use the SEARCH tool. If it was in fact excessive posts that were the culprit here wouldn't they be asking for $$$ for premium members to have better posting privileges, instead of limiting the SEARCH privileges of new users?

All the disclaimers that RC puts up cautions users to please lighten up on SEARCH requests - no mention of "please attempt to keep your posts at a minimum - it will help to improve our sites performance".

Seems to me that all us newbies who are bombarding the server with search requests to track down threads that already have the answers to our silly and obvious questions is probably at greater fault of "clogging up the site" than our redundant posts?

[androal]

Quote from the RC home page:

Our goal is to help educate people about the saltwater aquarium hobby and enhance awareness of the fragility of coral reefs around the world.

My absurd quote:

Pave the world! *@#! the rest! (ouch! that won't go over very well on a reef-friendly forum!)

Another failed attempt at sarcasm that seems to have gone over like a lead balloon!

You can't seriously think I actually feel this way!!!???

I am totally behind the RC mission! Just trying to have a little light-hearted fun! If you can't laugh at yourself, then...

Sorry. I guess some believe its just better etiquette to just keep the posts straight to the point.

Just the facts ma'Am.

[androal]

just last week i belive it was that members talked about this. And they spoke of how the ridges inside of the flex piping would cause more friction then the ridged(smooth inside) would making the ridgid more effective at the end.

No, i'm not the idiot I make myself out to be. (ok, maybe sometimes I am...)

Ok, i'm an idiot!

Whew - now that I got that out of the way!

I DID read this, and many other threads on the topic. (is this the one you were referring to Devil Man?)

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1345136&highlight=flex+piping+or+PVC

Nowhere in this thread did I find the conclusive answer I was looking for.

As usual - lots of views and opinions - little substantive facts. And a series of conflicting and opposing conclusions.

But I'm not complaining!

I actually have been enjoying reading through a lot of this stuff!
What a great hobby!

I guess it would be a lot simpler if we were all plumbers or had taken classes in fluid dynamics before!

In the end, what I love about the forum stuff is you are getting a bunch of peoples actual experiences. No amount of theoretical understanding can replace someone actually using the stuff!

[Devil Man]

mmm you are quite odd. but i can let go of my previuos thoughts about you. a joke here or there is fine i do it sometimes too. but i have a hard time trying to decifer when you are joking and not. either way yes less post/threads help to keep things smooth. searching on google,yahoo, or here on RC will help to find alot of things that you have questions to. and if you find an old thread that you want to ask a question to do it, that way we can just keep one thing going on one subject, or atleast try too. sometimes yes its hard to find things and you do have to start another thread. but i know for a fact that there are a bunch of these 90 vs 45 and ridged vs flex, threads now.

eh you know the biggest thing is that there is no realllllllll right answer for any one thing(most things)... big one being dsb and bb... sigh... lets not go there, but you can see, there will be 2 sides too things on here for the rest of life!

and i try to make sure that i dont insult people from where they are but insult them for what they say. so i will leave the people from NJ alone... they are not at fault.

[BeanAnimal]

<a href=showthread.php?s=&postid=12187518#post12187518 target=_blank>Originally posted</a> by Devil Man
btw i would really looking into getting a PRESURE rated sweep rather then that 90 that you posted a pic there. cause for your info, that is DWV. i will leave you to search to try to find out what that means since you seem to know so much. Why in the world would he need a pressure rated sweep? I am not aware of any return pump or manifold system that comes anywhere close to the design limits of clear vinyl, let alone DWV.

You sure appear quick to beat up on people but do not appear to be that well informed yourself.

I didnt put down you becuse you where a noob, i did it cause this has been talked about countless times, as a mater of fact i think in the DIY section there is a thread similar to this going on right now. You had no right to put him down no matter how stupid YOU thougt his question was. This forum is based on people asking questions and being helped by those willing to provide kind answers. We don't all have the same abilities or working knowledge. We don't all learn the same way. Posts like yours do nothing but anger people. Why not ignore questions that you find repetative, instead of giving flip or arrogant (and uninformed) answers?

i do know that it is consuming more sever space but some might not understand that. these threads that have beaten with a dead horse are getting out of hand. Getting out of hand in whos eyes? Yours? Who decides what questions are stupid and who is wasting server space? I don't see a beat horse here. I see an honest question regarding basic physics.

Here is what is funny... I certainly would consider questions and answers regarding reef related subjects a valuable use of resources. In the same spirit, posts such as your that DO NOT provide answers would be wastes of resources. Kinda ironic isnt it?

reef central doing i dont know what to help this problem that we all encounter with the server being cloged up, we all need to try to work together to keep this site running as smooth as possible, and in doing so searching before asking is one. Actually SEARCHING takes up many more resources than posting a question and getting a hundred answers. You are ripping the guy apart, but don't appear to have your facts straight.

you come across really immature doing so.

Hrmm?

[gpodio]

I found two 45s to be a little more silent than a single 90 on my drains... I suppose due to less turbulence. If you look inside the fittings, the 45s are actually quite well rounded rather than a harsh 45 degree bend.

I say go with the two 45s, it gives you a lot more angles to play with by rotating them and at times allows you to use less elbows by placing the 45s apart as someone else mentioned. Obviously if you can do it with flex PVC and reduce the number of elbows even further all the better.

Cheers

[Siffy]

<a href=showthread.php?s=&postid=12189567#post12189567 target=_blank>Originally posted</a> by androal
Sorry. I guess some believe its just better etiquette to just keep the posts straight to the point.

No, you obviously don't.

<a href=showthread.php?s=&postid=12189475#post12189475 target=_blank>Originally posted</a> by androal
I'm honestly curious about this - I DO want to do my part to help keep the site running as smooth as possible.

Then why are you replying to yourself multiple times?

As for which is better, use either one. If you can find a long radius 90, it is the best choice with respect to friction. More often than not though, they will not be available. So you're stuck with 1 short 90 or 2 45s.

Let's go with a sample friction chart from a manufacturer.
http://www.lascofittings.com/supportcenter/FrictionLossFittings.asp

Google will find you many more.

It's the same at near maximum flow capacity for most sizes.

But again, use either one. 1 90 to save space or 2 45s after you've convinced yourself it's so much less restrictive after reading that it is over and over again. I'll go away now and let the brainwashing continue.

[Siffy]

Bean, do you know enough about it to give a fully educated and mathematically supported answer? The last discussion I joined about this exact same question, I quoted a chart and an article by Sanjay. I was shot down, insulted, and told the charts were useless and inaccurate. They said the only answers with any certainty required solving partial diff equations. I asked the person to provide such equations and work one for the specific situation. They never said another word about it after that, so I went back to using a chart.

I'm not putting you on the spot if it sounded like that. I just respect your opinions and knowledge. And I would assume you to know. :)

[androal]

Ok, so... just to bring some of these thoughts together, here is a common scenario:

You are running water horizontally through 1" diameter PVC pipe.

The pipe run is 3 feet long - at which point you need to go around a corner.

1) 90 degree bend.
2) No space restrictions - you could choose ANY configuration you like to turn the corner.
3) Water flow is approx. 500gph through the pipe.

How would you rank the following solutions to "bend the pipe" with the minimum possible impact on the flow rate?

SOLUTION A) 90 degree bend? - everyone agrees this is the worst solution- if you have the space - go with something else.

SOLUTION B) 2 x 45 straight together, no spaces - everyone agrees this improves upon solution A.

SOLUTION C) 2 x 45 spaced a bit a part - some say this is an improvement over solution B - if you have the space to do it

SOLUTION D) A pvc 90 sweep - some say this trumps B - not sure if it beats C.

SOLUTION E) Flex Tubing - many say if you can do it - this is the best - some say the ridges add friction and make it a poor choice over rigid, but smooth, PVC pipe.

SOLUTION F) Smooth Vinyl Tubing - many say this is the BEST possible, but complain about leaky-barb fittings that make the rigid PVC a better ultimate choice.

Agree with the order ranking I suggest above?

[androal]

Then why are you replying to yourself multiple times?

Sorry!

Part of my newbie experience on RC includes the fact that i have never participated in forums before.

I guess my life has just been too busy - but now that I picked up the salt water hobby - I have been getting a huge benefit from this forum.

So, unfortunately for the members i am both

1) New to salt water

and

2) New to forums

I'm slowly but surely beginning to learn about both!

I see now that the proper forum etiquette is to reply only once, and include all your thoughts in the same post.

Still learning! Thanks for being patient!

[BeanAnimal]

<a href=showthread.php?s=&postid=12190084#post12190084 target=_blank>Originally posted</a> by Siffy
Bean, do you know enough about it to give a fully educated and mathematically supported answer? The last discussion I joined about this exact same question, I quoted a chart and an article by Sanjay. I was shot down, insulted, and told the charts were useless and inaccurate. They said the only answers with any certainty required solving partial diff equations. I asked the person to provide such equations and work one for the specific situation. They never said another word about it after that, so I went back to using a chart.

I'm not putting you on the spot if it sounded like that. I just respect your opinions and knowledge. And I would assume you to know. :)

The charts are useful in same cases, but not all. They will give you a basic idea of what each fitting profile adds in the way if friction. What they don't tell you is how much of a flow reduction is caused by the change in direction of the fluid. The water slams into the back of the elbow. The steeper the direction change, the more the turbulence affects the flow.

take two 45's 3" apart with 1' of pipe on the input and output. vs the same two 45's 2' apart with 1.5" of pipe on the input and output. The chart would tell you that both systems would flow the same because they have the exact same amount of pipe and identical fittings. In reality the system with the far spaced elbows will flow slightly more due to an overall decrease in turbulence (more laminar flow). Why? the two 45" elbows that are close together cause slightly more turbulence. Disturbed flow leaving one elbow enters the second elbow, becoming more disturbed than it would be otherwise.

I hope that makes sense. Do I want to do the math? No, there is software (very expensive) that does that. I have played with it before but have no practical use for it.

For our purposes it just does not matter that much. Yes, the long sweep elbow is better than a close 90 two 2 45s. Is it worth losing sleep over? No.

[kgross]

The simplest answer to this is go with large enough sized plumbing that you keep your velocity low and the amount of friction of any of the fittings will be so close to zero it does not make any measurable difference in flow.

If you think you need 1 inch, use 1.5 inch and you can use as many 90's as you like and you will still get more flow than the 1 inch with the best fittings money can buy (depending on flow rate again).

Kim

[Esquare]

This thread caught my eye because I am researching a similar question for my workshop involving the ducting for my dust collection. What I have learned (or more accurately what I have read) is that the 90 is the worst configuration and the 45’s spaced apart or a 90 sweep (depending on the radius of the bend) would be the better alternative. The 45’s next to one another is not much of an improvement over the 90. Here is a link to a very informative site on dust collection that provides a much better explanation then I can.

http://www.billpentz.com/woodworking/cyclone/index.cfm

Also, it explains the science behind the theory (assuming you are more intelligent than I and can understand it all because I can’t).

Once I got into this thread though, I developed more questions.

1. What is the best way to go about extracting information from this site?
2. If not the search feature (which doesn’t work most of the time) how else do you research threads that are no longer showing in the queue?
3. Do I need to seek approval prior to starting a thread or asking a question? I don’t mean to sound snide with this one but the attitude exhibited in this thread indicates to me that you must somehow prove yourself worthy before you can post.

I have invested a lot of time in this thread (considerably less than a lot of you but it’s my time and I value it highly) and I hope that it has not been in vain. If this forum is a private club or has grown so big that it can’t support new members than I would probably be best served looking elsewhere for my saltwater fix.

I apologized if I have come off rude but these are just some issues that have been nagging at me for some time and the tone of this thread just pushed me over the edge.

Well I feel better now. Go on and bash the heck out of me. J

P.S. As I typed this kgross posted a reply that has a lot of merit.

[BeanAnimal]

The best way of extracting information is to get a premium membership. It will help with the searches.

Google can be used to search the site with some success.

If all else fails, simply start a thread and ask a question. Pay no attention to people like Devil Man, people like that just like to cause trouble and be rude. No question is a stupid question.

As for the plumbing... the last few posts have been right on. If you are concerned then use spread out 45's or better, a sweep and if possible ALWAYS upsize the plumbing.

[Esquare]

Thanks Bean

[BeanAnimal]

No problem... let us know if you have any other questions.

[Devil Man]

<a href=showthread.php?s=&postid=12193410#post12193410 target=_blank>Originally posted</a> by BeanAnimal
The best way of extracting information is to get a premium membership. It will help with the searches.

Google can be used to search the site with some success.

If all else fails, simply start a thread and ask a question. Pay no attention to people like Devil Man, people like that just like to cause trouble and be rude. No question is a stupid question.

As for the plumbing... the last few posts have been right on. If you are concerned then use spread out 45's or better, a sweep and if possible ALWAYS upsize the plumbing.

i tried to not bother with this subject as i felt that i had made my point but i could no longer hold my touge. I am not saying that you have to prove yourself so that you can post before hand. but make the effort to try to do some reaserch before starting a thread. It gets quite anoying logging on to here to see the same types of thread posted over and over and over again by different people. You darn well know bean that this subject has been covered more then enough to start up another tread asking the samething. I just get extremely frustrated with people posting threads with no searching when the subject has been thoroughly talked about. so if you can make a argument against that bean please go right ahead since you seem so content coming after me.

[BeanAnimal]

Devil Man,

The only thing annoying about threads like this is seeing people like you unloading up on people who simply ask questions. You make it sound like you are the victim and I am beating up on you when I should be agreeing with you. I don't agree with you.

I (and many other people) answer the same questions over and over and we do so kindly. Sure it gets frustrating sometimes, but that comes with the territory.

Keep in mind:
1) The search features is not as available as most people would like. In many cases it is not available at all.

2) Google search is only partially effective and most people don't even know that it can be used.

3) There are around 7000 new posts a day and threads get buried very quickly.

4) Many people learn differently, some by direct response. Those responses help OTHERS to learn as well.

5) Each time a question is asked, there will be responses given that depend on who sees the question. Those responses build the knowledge base and in many cases can be more detailed than earlier responses to similar questions.

6) Even if the search function worked 100% of the time, It can be very frustrating to search on a topic and weed out relevant answers from the numerous results that are returned.


If you see a thread that appears to be redundant and you just can't bite your tongue, then ignore it and let one of us take care of answering the question.

In other words, be nice, it does not cost anything.

[gpodio]

I agree posts get burried so quickly that often people post questions like "where's that discussion on such and such..."

Perhaps the best tactic is to simply link to those burried threads when someone brings up a topic that's been discussed in the past. This way you don't waste too much time repeating things and you still help the person asking the question.

Plus repeated questions rarely get as much attention and discussion as when they first came up, it's probably better for the person looking for such info to be directed to past threads where the topic was discussed thoroughly anyway...

I agree searching this place is not easy, even for supporting members, I often have a hard time finding past threads.