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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Midwilshire on May 05, 2013, 04:36:14 AM

Title: Connection Between 3" Pipe and Black Tank
Post by: Midwilshire on May 05, 2013, 04:36:14 AM
We purchased used tanks onto which the previous owner had welded all fittings except the drop from the toilet.  I was planning on welding a 3" fitting for that, but came across this grommet:

(https://lh6.googleusercontent.com/-Fe-kkp5R3dY/UYZDH9H4RFI/AAAAAAAAAdA/3ilIASq47jA/s306-p-o/ameri-kart_3_rubber_inlet_grommet-53187-1.jpg)

This would be an easy and fast solution.  Our toilet sits directly on top of the tank, and the tank is tightly secured in place.  Does anyone have any experience with this type of grommet?  Do they work well?  Would you recommend any sealant to supplement the seal? 

Thanks!
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: Van on May 05, 2013, 05:26:39 AM
We used this fitting on our Poly tank, straight drop in with no issues and no sealant. 8.99 here. Pretty common in the rv industry
http://www.go-rv.com/coast/do/catalog/page?dealerId=1331&pageNum=418&productId=21290 (http://www.go-rv.com/coast/do/catalog/page?dealerId=1331&pageNum=418&productId=21290)
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: Jriddle on May 05, 2013, 07:33:40 AM
Quote from: Van on May 05, 2013, 05:26:39 AM
We used this fitting on our Poly tank, straight drop in with no issues and no sealant. 8.99 here. Pretty common in the rv industry
http://www.go-rv.com/coast/do/catalog/page?dealerId=1331&pageNum=418&productId=21290 (http://www.go-rv.com/coast/do/catalog/page?dealerId=1331&pageNum=418&productId=21290)

Yup what I used also works fine. Make sure to cut the hole the right size for the grommet.

John
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: Iceni John on May 05, 2013, 10:07:43 AM
I used two of the smaller size of this grommet for the gravity-fill inlets into the tops of my fresh water tanks, because those tanks' inlets had to be self-connecting as I raised them up into position under the floor.   Make sure your tank's wall thickness matches the grommet  -  if your tank's too thick you may need to shave down the opening slightly.   3" ABS pipe should fit easily through it, but if it hangs up and tries to dislodge the grommet from the opening (that happenend with me, twice :-\) some imaginative folk recommend a water-based non-toxic readily-available biodegradable lubricant, i.e. KY Jelly!   It's also a good idea to chamfer the bottom of the poo pipe so it will slip through better.

John
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: belfert on May 05, 2013, 12:02:39 PM
I used one of those grommets for my 3" pipe and it works great.  I even used one for the bottom drain and no leaks yet.  I would not recommend for the drain!  I think I'm running on borrowed time using this for the drain.
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: gus on May 05, 2013, 03:06:28 PM
You can also find just plain rubber sleeves of different lengths at your local hardware store.

In any case sewer pipes of any length need a couple of flexible joints for vibration resistance and for easy maintenance.
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: Midwilshire on May 06, 2013, 06:53:18 PM
Thanks for the confirmations, gents!
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: Nick Badame Refrig/ACC on May 07, 2013, 06:43:31 PM
Hi Mike,

I also used the same fitting with no problems!

Good Luck
Nick-
Title: Re: Connection Between 3" Pipe and Black Tank
Post by: Van on May 08, 2013, 05:05:51 AM
If you size the hole correctly, the seal will expand slightly in the hole and will make a nice seal with no sealant required. Be sure to properly add a tank vent also  ;) I used a little 40 wt oil to easily insert the pipe  :)