Black tank construction?

[Tbos]

I have a 2014 Passport 238ML. What type of construction was used for the black and grey tanks? I've heard that if the tanks are made with a chemical bonding being used to connect the top to the bottom you should not travel with much water/waste in them? It could cause them to split.

[Festus2]

I have a 2014 Passport 238ML. What type of construction was used for the black and grey tanks? I've heard that if the tanks are made with a chemical bonding being used to connect the top to the bottom you should not travel with much water/waste in them? It could cause them to split.

Tom -
RV holding tanks are made of high density polyethylene, are molded, seamless and one piece. Some of the older tanks may be made from ABS plastic but they too are molded, one piece units. They are not made up of two pieces welded or bonded together. Where did you hear that they have a top and a bottom joined together with some chemical bonding agent and could split if there is too much water in them?

They are not "bulletproof" and have been known to develop cracks but they aren't going to split in two because of the weight of the contents. I would be more worried about the tank supports than the tank itself.

[RSD559]

Tom -
I would be more worried about the tank supports than the tank itself.

Amen to that. I'm much more concernred about bracing.

[Tbos]

I have not heard the tanks on the passports were a problem, just that there were some being used in the industry that were 2 piece. A friend has an older 5th wheel and they had this issue with theirs. I don't know the brand, model, or year. I just wanted to make sure I don't have to worry if I have to travel with full tanks. I don't remember seeing any support straps under my black or grey tanks. Should there be some?

[Steve S]

I for one wouldn't travel with them full or part full as the supports just aren't made for any weight.

[hankaye]

Tbos, Howdy;

I have a 2014 Passport 238ML. What type of construction was used for the black and grey tanks? I've heard that if the tanks are made with a chemical bonding being used to connect the top to the bottom you should not travel with much water/waste in them? It could cause them to split.

I've found that when i have a question such as yours there are several
avenues that can be utilized to find an answer, one where you ask for
opinions and a second where you can get facts from the manufacturers.
here's a start for #2 ...
https://www.google.com/search?q=RV+holding+tanks&ie=utf-8&oe=utf-8

and ... by poking around a wee bit you can see actual engineering
drawings of what they actually look like.
I'm not sure whose, in particular, Keystone uses but I'm sure that getting
a general idea of what they look like will help you out to some extent.

Didn't mean to sound haughty or sarcastic, so please don't take it as
such.

hankaye

[tirnanah]

I've traveled all over Alaska (probably on some of the roughest roads you can find any where) with all my tanks full (or close to it) and never had a problem... No one would be able to boondock if you couldn't travel with the tanks full...

I am interested to drop my cholorplast next year (for some other work) and be able to check things out. I'll be interested to see how well the tanks are actually secured...

Doug

[SteveC7010]

A lot of folks have the luxury of always camping with full hookups so a full tank is never a concern.

But a lot us regularly dry camp with no hookups. That means we have to travel with full tanks. It's rare to hear about a holding tank falling out of a trailer. Yeah, it happens, but most of the other bad stuff that can happen to an RV owner happens a lot more often than a black or gray tank dropping out. If you don't believe me, just look around this forum. Very few, if any, black or gray tanks falling out. Lots busted vacuum breakers, cracked plastic trim, ripped awnings, bent this and thats, holes in luan walls and doors, the list is endless.

My black and gray tanks are 38 gallons each. 38x8.4 is about 302 pounds if the tank is truly full. It does not take that much strapping and such to safely hold 302 pounds plus what ever the tank between two steel I-beams. Even folks with the larger 46 gallons tanks are only looking at a max of 386 pounds.

I regularly camp in a campground that has 355 sites adjoined by another with another couple of hundred sites. There are no hookups anywhere in the combined parks. Thousands of campers every year travel with full tanks with nary a problem at just this one park.

I always travel with some water in my fresh tank, usually at least half full. Because we dry camp so much, the fresh tank is full much of the season. Again, thousands of campers do the same thing without incident.

These tanks are held up in the trailers better than you might think. Otherwise, the RV manufacturers would have much bigger problems than they do.

If anyone is really worried about a tank falling out, have your dealer add an extra strap or two.

[Face Down]

From doing a quick Google search they are either made of Polyethylene via a roto-mold process or ABS using a twin-sheet vacuum formed process, the latter is "pinched" together from two separate sheets of plastic during the forming process. A roto-mold part will be a little more robust but that being said, many new automotive fuel tanks use the twin sheet process using a layered ABS material for CARB compliance.

If they make the roto-mold tanks from XLPE vs. Linear....they are pretty much bullet proof, but sadly with mfg's trying to save every dime I am guessing not.

https://www.youtube.com/watch?v=DkSS-UdAzkI

[Tbos]

Tbos, Howdy;



I've found that when i have a question such as yours there are several
avenues that can be utilized to find an answer, one where you ask for
opinions and a second where you can get facts from the manufacturers.
here's a start for #2 ...
https://www.google.com/search?q=RV+holding+tanks&ie=utf-8&oe=utf-8

and ... by poking around a wee bit you can see actual engineering
drawings of what they actually look like.
I'm not sure whose, in particular, Keystone uses but I'm sure that getting
a general idea of what they look like will help you out to some extent.

Didn't mean to sound haughty or sarcastic, so please don't take it as
such.

hankaye
Hankaye, Thanks, I use this forum to help point me in the right direction when I'm short on time.