What fittings for fresh water tank?

stand up or sit down...to sink or not to sink...want or got gas...post your Q&A here..........

What fittings for fresh water tank?

Postby Xtremespeed » Tue Mar 13, 2012 10:10 pm

I installed 2 white fresh water tanks but I'm worried about the fittings that attach to the tanks. I used pex tubing and shark bite fittings, but the fittings don't get very tight on the tanks no matter how much I turn them. I believe they are 3/8 pipe thread. Do I need special fittings here? Some kind of sealant?
Xtremespeed
Teardrop Advisor
 
Posts: 86
Joined: Thu Dec 15, 2011 1:44 pm
Location: NE Texas

Re: What fittings for fresh water tank?

Postby Shadow Catcher » Wed Mar 14, 2012 5:45 am

Our installation is PEX but the fittings into the tank are spin fittings which fuse themselves with the tank. There are fittings available to use with water tanks that are specialized. And yes the shark bite... fittings are not tight, they rely on an O ring for sealing. I made a number of modifications to our plumbing and I am waiting for good consistent warm weather to test for leaks but will do a pressure test using air from the compressor.
User avatar
Shadow Catcher
Donating Member
 
Posts: 5599
Images: 192
Joined: Sat Apr 11, 2009 8:26 pm
Location: Metamora, OH

Re: What fittings for fresh water tank?

Postby Xtremespeed » Wed Mar 14, 2012 7:13 am

Thanks for the reply. I know the shark bite fittings are supposed to move, I was referring to where they are screwed into the tanks though. So I need to remove them and install special fittings. Will I have to get these from an rv supply store? What do I ask for? Spin fittings? My tanks have 3/8" female pipe fittings thermo welded to the tanks.
Xtremespeed
Teardrop Advisor
 
Posts: 86
Joined: Thu Dec 15, 2011 1:44 pm
Location: NE Texas
Top

Re: What fittings for fresh water tank?

Postby Shadow Catcher » Wed Mar 14, 2012 7:47 am

If your tank already has fittings use them. The thermo welding is often accomplished by spinning, the friction of spinning the fitting against the tank is one way to accomplish that. This can also be accomplished using plastic welding which leaves a visible weld bead, this uses hot air and plastic welding rod. If you have an access in the top of the tank fittings that have an inside seal/gasket are usable and ports can be added to the top of the tank can be added if you do not have one. http://www.usplastic.com is a source for most everything plastic, they have it all.
User avatar
Shadow Catcher
Donating Member
 
Posts: 5599
Images: 192
Joined: Sat Apr 11, 2009 8:26 pm
Location: Metamora, OH
Top

Re: What fittings for fresh water tank?

Postby Dale M. » Wed Mar 14, 2012 9:51 am

If you are expecting a plastic fitting screwed into a plastic fitting to get really tight like a metal fitting.... Don't... Plastic fitting usually only need to be tight enough to seal.... If you think about it the male fitting will compress because its soft plastic (as opposed to steel or brass or copper) and the female plastic fitting will expand... The amount of "tight" you can get on a fitting is generally referenced the type of materials you are using...

A simple example if joining PVC pipe to steel pipe... IF you use a female plastic fitting and a male steel fitting, the plastic female fitting will fail because the steel pipe stretches it to beyond its burst point (tensile strength) ... But if you use plastic male into steel female it will last pretty much forever because the steel female will not expand past its tensile strength breaking point because the plastic male can not exert enough pressure to force steel pipe to break (again tensile strength) ... Learned this doing yard sprinkler system repairs....

Dale
Lives his life vicariously through his own self.

Any statement made by me are strictly my own opinion.
You are free to ignore anything I say if you do not agree.

Image
User avatar
Dale M.
2000 Club
2000 Club
 
Posts: 2636
Images: 18
Joined: Thu Jun 09, 2005 8:50 pm
Location: Just a tiny bit west of Yosemite National Park
Top

Re: What fittings for fresh water tank?

Postby Xtremespeed » Wed Mar 14, 2012 10:00 am

Oops. Sounds like I should have used plastic fittings then. I hope I didn't mess up the threads on the tank. I used brass shark bite fittings. So I need to find some plastic fittIngs for pex tubing. Do I need any kind of sealant or Teflon tape, or just dry fit them? I take from your explanation that you don't put anything on them?
Xtremespeed
Teardrop Advisor
 
Posts: 86
Joined: Thu Dec 15, 2011 1:44 pm
Location: NE Texas
Top

Re: What fittings for fresh water tank?

Postby Shadow Catcher » Wed Mar 14, 2012 11:53 am

I would use teflon tape and not worry about the fitting being plastic, brass will work fine and quite frankly you might not even need that. Just do a leak test, if it does not leak you are good to go :D
User avatar
Shadow Catcher
Donating Member
 
Posts: 5599
Images: 192
Joined: Sat Apr 11, 2009 8:26 pm
Location: Metamora, OH
Top

Re: What fittings for fresh water tank?

Postby Xtremespeed » Wed Mar 14, 2012 2:50 pm

That's actually what I did. 1/2" male shark bite with brass reducer to 3/8" brass nipple with Teflon tape in to the 3/8" female threads on the tank. It just bothered me that I could easily move the fitting with my hand and I'm worried that it will leak. I don't think I have any way to connect my compressor to the tank to pressure test it. Obviously I'm no plumber. Lol!
Xtremespeed
Teardrop Advisor
 
Posts: 86
Joined: Thu Dec 15, 2011 1:44 pm
Location: NE Texas
Top

Re: What fittings for fresh water tank?

Postby Dale M. » Wed Mar 14, 2012 2:57 pm

Xtremespeed wrote:Oops. Sounds like I should have used plastic fittings then. I hope I didn't mess up the threads on the tank. I used brass shark bite fittings. So I need to find some plastic fittIngs for pex tubing. Do I need any kind of sealant or Teflon tape, or just dry fit them? I take from your explanation that you don't put anything on them?


No not particularly..... Just screw brass fitting in enough that it does not leak.... Use Teflon tape if it suits you... IF it does not leak then there is no problem....

Dale
Lives his life vicariously through his own self.

Any statement made by me are strictly my own opinion.
You are free to ignore anything I say if you do not agree.

Image
User avatar
Dale M.
2000 Club
2000 Club
 
Posts: 2636
Images: 18
Joined: Thu Jun 09, 2005 8:50 pm
Location: Just a tiny bit west of Yosemite National Park
Top

Re: What fittings for fresh water tank?

Postby Xtremespeed » Wed Mar 14, 2012 3:07 pm

Thanks guys. Guess we'll just have to see this evening if it seals. The loose fittings just have me uneasy.
Xtremespeed
Teardrop Advisor
 
Posts: 86
Joined: Thu Dec 15, 2011 1:44 pm
Location: NE Texas
Top

Re: What fittings for fresh water tank?

Postby Wobbly Wheels » Wed Mar 14, 2012 4:12 pm

You can also use a polysulfide sealant on the fittings as long as it's food grade - Sikaflex 291 does it nicely and will prevent fittings from spinning. If you have a stub coming straight out of the tank, a metal fitting can vibrate enough to back itself out enough to leak through the threads - an elbow will prevent that.
Liquid teflon also has more 'grab' than tape does.
User avatar
Wobbly Wheels
Donating Member
 
Posts: 1080
Joined: Tue Mar 15, 2011 9:51 am
Top

Re: What fittings for fresh water tank?

Postby Xtremespeed » Thu Mar 15, 2012 8:04 am

Got everything plumbed and none of the fittings leak. That would seem like good news, and it was until I noticed one of the tanks has a leak. I bought them a long time ago, so it looks like I'm going to have to buy another one. :cry:
Xtremespeed
Teardrop Advisor
 
Posts: 86
Joined: Thu Dec 15, 2011 1:44 pm
Location: NE Texas
Top

Re: What fittings for fresh water tank?

Postby Martiangod » Thu Mar 15, 2012 12:00 pm

Look for someone who does plastic welding, or get a plastic tank epoxy repair kit
If it ain't broke, fix it till it is

Chris

Deep in the Heart of Nowhere
The topper viewtopic.php?f=50&t=58140, gone to a new home to be converted
into an ice fishing shack...FREEBIE !!! for a nice young family
The trailer viewtopic.php?f=50&t=48156
User avatar
Martiangod
500 Club
 
Posts: 856
Images: 432
Joined: Mon Jan 09, 2012 10:39 pm
Location: Peace River, Alberta
Top


Return to Plumbing & Propane Secrets

Who is online

Users browsing this forum: No registered users and 1 guest