Reply
 
Thread Tools Search this Thread Display Modes
 
Old 01-20-2014, 08:28 PM   #1
Rivet Master
 
dbj216's Avatar

 
1986 34' Limited
1966 24' Tradewind
Conifer , Colorado
Join Date: Jun 2009
Posts: 3,124
Mounting New Holding Tanks

Okay, my new Inca Plastics holding tanks are going under the trailer. The tanks have molded mounting ledges. Essentially the tanks are T shaped, designed to hang between mounting rails. I'm using 1 1/2 angle irons cut to fit between the frame rails. The angle irons rest on the lower lip of the frame rails.

I have seen some clever and elaborate mounting frames made by folks in these forums. I am neither. My 86 Airstream was not elaborate. I believe the tanks were held in place by the tank pan, and the hose clamps to the vent pipes and dump manifold. When I dropped the pan, the tanks were flopping around hanging by the vent pipes. I was surprised how they are just like a suit case in a trunk of a car. Rather free to find a nice spot to ride along. The Styrofoam insulation was mostly crumbs and not adding much support.

So I am thinking about using a 5/16 or 3/8 bolt 5" long to clamp each end of the angle iron and the top of the frame and then squeeze the angle iron snug against the tank. The bolt heads would be above the floor, but not in visible areas. The bolt heads would be in storage compartments, under the water heater, or closet area. Loctite would secure the lock nuts. Then the tank pan would be bolted to the lower frame rails and hold the tank foam insulation and also further clamp the tanks.

Any comments on this idea for mounting holding tanks?

David
Attached Thumbnails
Click image for larger version

Name:	1401 Waste Tank Black.jpg
Views:	501
Size:	308.3 KB
ID:	204062  
__________________

__________________
dbj216 is online now   Reply With Quote
Old 01-20-2014, 08:39 PM   #2
Figment of My Imagination
 
Protagonist's Avatar
 
2012 Interstate Coach
From All Over , More Than Anywhere Else
Join Date: Dec 2011
Posts: 10,305
From an engineering standpoint, never use hose clamps as load-bearing devices. Hose clamps are meant to form a seal, not to support a load.

On the other hand, you can get pipe hangers and mount them so that they support the flanges coming out of your tanks, as long as the flanges are long enough that the pipe hangers don't interfere with the hose clamps or vice versa.
__________________

__________________
WBCCI #1105
TAC LA-4

My Google-Fu is strong today.
Protagonist is online now   Reply With Quote
Old 01-21-2014, 06:02 AM   #3
Rivet Master
 
dbj216's Avatar

 
1986 34' Limited
1966 24' Tradewind
Conifer , Colorado
Join Date: Jun 2009
Posts: 3,124
Thanks for your reply. I confused my readers. My 86 tanks are basically supported by the tank pan. When you remove the tank pan, the tanks are then left hanging by their vent pipes. I will not use this tank mounting method on my 66 Trade Wind.

I propose to support the tanks under my 66 with angle irons hung from the frame rails with bolts. I will draw the angle irons up snug so the tanks are clamped to the bottom of the subfloor. There would be no tank weight on the drain pipes. And then I will surround the tanks with my insulated and heated tank pan. Do you think this will work okay.

David
__________________
dbj216 is online now   Reply With Quote
Old 01-21-2014, 07:10 AM   #4
Figment of My Imagination
 
Protagonist's Avatar
 
2012 Interstate Coach
From All Over , More Than Anywhere Else
Join Date: Dec 2011
Posts: 10,305
Quote:
Originally Posted by dbj216 View Post
I propose to support the tanks under my 66 with angle irons hung from the frame rails with bolts. I will draw the angle irons up snug so the tanks are clamped to the bottom of the subfloor. There would be no tank weight on the drain pipes. And then I will surround the tanks with my insulated and heated tank pan. Do you think this will work okay.
Without seeing diagrams and dimensions, I can only speculate, but it certainly seems workable. But point of interest, instead of angle iron (|_), you might use channel (|_|), so that you've got two flanges, and the flanges don't have to be as large to provide the same stiffness.
__________________
WBCCI #1105
TAC LA-4

My Google-Fu is strong today.
Protagonist is online now   Reply With Quote
Old 01-21-2014, 08:17 AM   #5
Rivet Master
 
Alphonse's Avatar

 
2010 28' Flying Cloud
Lower Alabama , USA
Join Date: Mar 2012
Posts: 649
You mention that tank is designed to be supported this way. Does the manufacturer agree that it can be supported by hanging it versus supporting with straps like the newer Airstreams? From the photo, it appears that the tank is quite robust.

As you know some of the tanks need support across the bottom. A 40 gallon tank will weigh ~330 lbs. when full and that will deflect the bottom of the tank. For example, a freshwater tank in the newer Airstreams must be supported across the bottom of the tank and that is accomplished by the tub that holds the tank and straps that are run fore and aft.

In your case, your new BW tank appears to be designed to hang and if so, that is excellent. The question then becomes what size angle or other support to use and how to attach it. So for us perfectionist types, a few questions and/or comments:

1. What is the volume of the tank and how much does the empty tank weigh? (i.e how much will it weigh full?)

2. Does the manufacturer agree that it can simply be hung with no under tank support needed? From your post, I assume yes.

3. What is the port to starboard length of the tank that would be sitting on top of the support angle or channel? It appears that the tank sits well between the longitudinal frame members and it is long enough to exert a fairly distributed force over the length of your proposed angle support (good).

4. Your notion of bolting the support in is good (allows for removal if necessary). It appears that you have already notched the angle to get the top of the tank close to the subfloor, it that correct?

5. Is your intention to drill through the upper flange of the frame channel and bolt through the frame and subfloor? This will require you to sandwich the tank to the subfloor and you will need to tension the bolts and if that is overdone, you deflect your support and compress a plastic tank at the corners which could cause it to fail. As an alternative, couldn’t you allow the supports to ride the frame as shown in your photo versus pulling the supports and tank up snug to the subfloor? An alternative to consider would be to weld some ends on the angle which help keep them from rotating on the notch and clip them or bolt them to the frame. Bolting to the frame could even add some frame stiffness if done properly.

6. Without any ciphering on the size of the angle for structural support, it appears that it should be heavy enough. I would run a number or two to confirm that however.

In summary, I really like the looks of that tank. Your frame work looks outstanding as well. I just replaced the freshwater tank on a later model Airstream and was surprised at how flimsy it is and the construction of the tank fittings. If your new tank can be hung like this without the need for straps, this will be a first class installation.

I hope I haven’t confused your post with these questions and comments. Please keep us posted on how you end up going on this install.
__________________
Alan
"If you must choose between two evils, pick the one you never tried before!"

Air #64439
Southeastern Camping Unit WBCCI #5033
TAC AL-8
2017 Canopenian
Alphonse is offline   Reply With Quote
Old 01-21-2014, 09:58 AM   #6
Rivet Master
 
truckasaurus's Avatar

 
1960 33' Custom
Saskatoon , Saskatchewan
Join Date: Jun 2005
Posts: 1,182
Images: 25
I hadn't looked at the Inca site in a while and notice that they now have an Airstream tank specific pdf! Both current and vintage which is very cool. I dropped them a note asking about tank support recommendations and if I get a useful reply I'll post the ideas up.
http://www.incaplastics.com/AirstreamR1.pdf
__________________
1960 Sovereign 33' Pacific Railroad Custom
truckasaurus is online now   Reply With Quote
Old 01-21-2014, 12:26 PM   #7
Rivet Master
 
Skatiero's Avatar

 
1986 32' Excella
Currently Looking...
Canton , Georgia
Join Date: Jun 2011
Posts: 1,335
Images: 25
Very cool link, thanks for sharing! (Or should I say, tanks for sharing?)
__________________
Skatiero is offline   Reply With Quote
Old 01-21-2014, 07:28 PM   #8
Rivet Master
 
dbj216's Avatar

 
1986 34' Limited
1966 24' Tradewind
Conifer , Colorado
Join Date: Jun 2009
Posts: 3,124
Thank you folks for your thoughtful replies. Yes, I found Inca Plastics catalog of old tanks very useful. They have been in business more than 40 years. I searched through their catalog until I found a tank that fit between my frame rails, and fit between my frame stringers in the frame bay under the toilet. And they introduced me to the rubber grommet method of sealing inlet pipes.

The tanks (black and gray water) are 50 inches long and a narrow 17 inches wide. They are 25 gallon capacity. The polyethylene wall thickness is 3/16. The tanks weigh about 15 lbs empty.

Yeah, maybe I ought to change to squares instead of angle irons. It would make a more robust mounting. The tanks have some molded details on the bottom that will add stiffness. The bottom is only 14 inches wide. The mounting channels are 1 1/2 each. It so happens my 1 1/2 angle irons just barely fit in the frame rails. I had to notch them about 3/16 of an inch to get them upright. But the weight of the tanks will mostly be trapped between the angle irons and the frame rails, as will as hanging on the bolts.

My Trade Wind has "stiffeners" added to the 5/8 plywood subfloor. These 5/8 plywood stiffeners interfere with my selected tank mounting areas. So I will add more 5/8 plywood to make a smooth, flat surface for the tanks to clamp against. I do not plan on over tightening the draw bolts, only to make the angle irons snug against the tanks.

The tank pan will provide support to the bottom of the tanks, especially when they are full. My old 66 Trade Wind had the neatest molded foam insulation and support that I have seen. See the photo below. This is much better than the cheap Styrofoam used in my 86. Unfortunately the 66 tank pan rusted completely away. On the 66, I'll use foam insulation board, and then bolt the tank pan to the frame. The tank pan will be robust enough to take the occasional rock or road kill that I might run over.

Inca Plastics is a viable source for your new black and gray tanks. IMO. They have lots of configurations to choose from.

David
Attached Thumbnails
Click image for larger version

Name:	1311 Tank Insulation 2.jpg
Views:	141
Size:	197.7 KB
ID:	204127  
__________________

__________________
dbj216 is online now   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:24 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.