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-   -   Dry fitting PVC (http://www.reefcentral.com/forums/showthread.php?t=1897538)

scbrooks87 08/26/2010 05:01 PM

Dry fitting PVC
 
Ok so every time I try to do any dry fitting for my PVC stuff, it really like to get stuck... It will stick into place and is all but impossible to pull back apart... I am a plumbing noob, and dont know the tricks of the trade yet.


Suggestions on how to get the PVC to just work easier? lol.

Once it's dry fit, I plan to just mark it in place to put it back together easer with the glue.

Its all slip fittings

Thanks!
-Scott

rwb500 08/26/2010 05:19 PM

i wouldnt put anything on it, especially vaseline, because unless you clean it off really well it might interfere with the gluing process.

honestly, i would just avoid dry fitting unless its very necessary. pvc pipe likes to get stuck.

scbrooks87 08/26/2010 05:37 PM

I need to dry fit just so I know it's all gonna match up when I do the final fitting, I dont wanna SW it all together and have it not fit lol.

So it is just a pain and that just kinda how it goes?

reefermad619 08/26/2010 05:49 PM

Pretty much. You have to muscle it. I know some people put water based lube on it to dry fit. Like ky jelly. It wipes off really easy.

billdogg 08/26/2010 05:49 PM

don't clean the parts first, and don't push them together any harder than you must.

milkman55 08/26/2010 05:53 PM

Just measure the depth of the slip fitting and allow for the extra length when you cut. No need to dry fit. Write it down if working with fractions is a challenge. Most the 1" PVC has a 1" socket depth which makes it easier. Once you add the PVC cement, the pipe will go easily to the bottom of the fitting with very little pressure, just a slight twist.

Qwiv 08/26/2010 06:13 PM

I dry fit everything as I like to look at it and tweek things all the time on smaller tanks. Big ones aren't much of a worry.

To get them apart I just use some plier grips. Always works.

LaOtIn 08/26/2010 06:19 PM

i always dry fit plumbing so i can look at it...then change it, look, change, look....

yeah i change it a couple hundred times before gluing :)

ive never thought about using any kind of lube tho, i just turn red in the face from time to time pulling them apart /shrug

scbrooks87 08/26/2010 06:27 PM

Thanks for all the replies... Much appreciated... I'm very glad to know it isnt just me that has the problem haha. I'll manage then, I would like to dry fit for the same reason, I have my plumbing all drawn up in cad, but who know if that will translate when I actually build lol


:blown: thats me with PVC

der_wille_zur_macht 08/26/2010 06:47 PM

Here's another vote against dry fitting. Most of the time, when you dry fit PVC, even if you force it, it won't sink into the socket as far as it will once it's wet with glue - this means your dry fit will essentially come up longer than the finished piece, unless you're really careful during assembly to not bottom things out when you glue them (which isn't very good practice).

billsreef 08/26/2010 09:45 PM

Quote:

Originally Posted by jon.elrod@gmail (Post 17569105)
you could try some vaseline?(spelling?)

Nothing like taking a wild guess and giving bad advice just to boost your post account.


rwb500 08/26/2010 09:48 PM

Quote:

Originally Posted by der_wille_zur_macht (Post 17569595)
when you dry fit PVC, even if you force it, it won't sink into the socket as far as it will once it's wet with glue


exactly

DanMgy 08/27/2010 09:49 AM

Here is a quick science lesson for you...
 
PVC uses what's called "Interference Fit", this design has very high tolerances which makes it near impossible to dry fit PVC.

Why you ask?

Well the "Interference Fit" combined with the solvent is what allows PVC to create a sold bond/connection. When you apply the solvent and push the two pieces together the high tollerance is creating friction between the two pieces which causes the PVC to actually melt. So through this process you are experiencing "Thermal Expansion". This is what explains why you have to hold the joint tightly together as it wants to push out.

Push the joints together >>> creates friction>>> PVC melts and expand>>> the melted PVC joins together>>> it then cools and contracts>>> a new bond/weld is created. :dance:

Hence why you use PVC solvent and not PVC glue.

HV1990 08/27/2010 10:03 AM

der_wille_zur_macht I usually agree with you on 99% of all things but dry fitting is a must for pvc. I could never see why you would want to eye ball things that will hold water with flow? Been landscaping for quiet a while and I know not all people can eye ball an inch let alone a foot.

scbrooks87 08/27/2010 10:04 AM

I love science lol... I'm not very good at science, but I love it!

But really... I watch mythbusters so that makes me an instant science expert...

Anyways, I guess what I'll have to do as actually use the skills I DO have with math and plan this out before putting everything together... Man, sounds like work...

Anyone see any problems with going one fitting at a time, then measuring and cutting for the next fitting as I go? Or should I just try and make it all up before putting anything in place and hope I did my math right?

This is my first time doing anything with plumbing so I'm about as noob as we can get here...

Thanks!
-Scott

der_wille_zur_macht 08/27/2010 10:10 AM

Quote:

Originally Posted by HV1990 (Post 17572078)
der_wille_zur_macht I usually agree with you on 99% of all things but dry fitting is a must for pvc. I could never see why you would want to eye ball things that will hold water with flow? Been landscaping for quiet a while and I know not all people can eye ball an inch let alone a foot.

I'm not advocating eyeballing things by any means - quite the opposite. Measure and cut accurately, and both eyeballing and dry fitting will be meaningless!

I'm also not suggesting that dry fitting is evil. If you've got something tricky and you're not sure you measured correctly, by all means, dry fit - but keep in mind that when you glue it up, things will be "shorter" since the pipe will likely slide deeper into each socket.

Quote:

Anyone see any problems with going one fitting at a time, then measuring and cutting for the next fitting as I go? Or should I just try and make it all up before putting anything in place and hope I did my math right?
No need to do complex math or figure and cut every piece before you put it all together. Measure and assemble as you go. As long as you carefully plan your routing, this will be pretty foolproof.

scbrooks87 08/27/2010 10:46 AM

Thanks DWZM, I think Im just overcomplicating things... Ive done it every step of the way so far, why stop doing it now? haha

Tony78 08/27/2010 11:06 AM

There's also the option of flexible PVC, sometimes called "SPAflex". It's available in your local home improvement store. It's the same OD as the equivalent sized schedule 40 PVC but it's flexible-ish. It will cement into standard PVC fittings and is a bit more forgiving when fitting your plumbing together. I'd DEFINITELY recommend a section of this stuff coming off your return pump. The flexibility of the PVC does wonders to absorb vibrations and quiet down your return pump. You can join the flexible PVC to rigid schedule 40 PVC via a union joint if needed.

scbrooks87 08/27/2010 11:44 AM

Quote:

Originally Posted by Tony78 (Post 17572303)
I'd DEFINITELY recommend a section of this stuff coming off your return pump. The flexibility of the PVC does wonders to absorb vibrations and quiet down your return pump.

My pump's fitting coming off of it is 3/4" ribbed tube connector... My design consists of a 3/4" ID tubing coming off the pump for a couple inches, then converts to PVC connectors from there on up.

Would this be acceptable? I thought it would have the benefit of keeping things quieted from the vibrations.

Tony78 08/27/2010 11:49 AM

Quote:

Originally Posted by scbrooks87 (Post 17572460)
My pump's fitting coming off of it is 3/4" ribbed tube connector... My design consists of a 3/4" ID tubing coming off the pump for a couple inches, then converts to PVC connectors from there on up.

Would this be acceptable? I thought it would have the benefit of keeping things quieted from the vibrations.


Yeah that will definitely work. Having a section of any flexible tubing in the return line helps separate the vibrations from the pump to the rigid plumbing. I'm not sure what your setup looks like, but you may consider flexible PVC instead of rigid PVC after it converts. The flexible stuff will allow you to open up the radius of each bend (a curved piece of pvc vs a 90 degree hard elbow). The smoother radius turns of the flexible PVC will help with flow from the return pump vs rigid PVC elbows.

Good luck and post some pics of your plumbing if you can. We'd love to see it.

scbrooks87 08/27/2010 12:03 PM

I'll post some pics of what i've got so far for the fittings when im on my lunch break. They are on my phone and ill just email them to myself.

Pickupman66 08/27/2010 12:05 PM

I sure this goes without saying, you can always cut more off, but you cannot add it back on.

on the complex plumbing I did under my tank to both utilize existing fittings and hit a specific part of the floor, I cut and fit each part as I went. I dry fit most of it but left extra room knowing that the solvent would allow a closer fit than dry. I did have one issue when it came to the returns, my cross pipes were too short after glue and I had to cut and splice to make it fit. it sucked, but ended up working. but for the most part, I cut and glued each piece then moved on. the tank mains are 2" and the CL is 1.5"
http://i53.photobucket.com/albums/g5...d/CIMG0978.jpg
http://i53.photobucket.com/albums/g5...d/CIMG0991.jpg
http://i53.photobucket.com/albums/g5...d/CIMG1057.jpg

sweetleaf 08/27/2010 12:45 PM

Get yourself some 99% plumbing silicone and throw a dab around the pipe fitting and "dry-fit." After you're positive everything is a-OK, disassmble, wipe off residue and glue it up. Should help with your stuff sliding much better, and I doubt that this method would have negative effects on your eventual tank.

scbrooks87 08/27/2010 01:53 PM

is the plumbers silicone going to adhere at all while working? I mean does it dry and stick like normal silicone?

der_wille_zur_macht 08/27/2010 06:54 PM

"Plumbing silicone" is a lubricant (grease), not an adhesive. It won't stick things together.

It will, however, totally interfere with the PVC cement you use to glue the plumbing together, so I would not advise using it to dry fit components unless you carefully clean every trace of it from the plumbing afterwards.


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