My portapotty almost exploded!

[Malena]

Okay, it didn't almost explode. It got stuck in the close-fitting cabinet. But it could explode!

We went from the coast to the eastern Sierra via Tioga pass (~9940 ft) with most of the trip (especially the climb) at temperatures over 100 degrees. The camper where the portapotty lives stays cool and probably didn't exceed 85. As we were going up, the potty was used once at around 5000 ft. When we reached our destination on the other side of the pass at about 7600 ft, the bottom section of the Thetford was found to be swollen too much to get it out of the cabinet until someone reached in (into the cabinet that is) and opened the valve. It was off its little feet and wobbling on its round base. Really, noticeably, bloated.

I've never heard of portapotties being affected by altitude although it certainly makes sense. I don't think it's very good for the potty to be flexed like that but I'd rather not travel with it vented open.

Is there a trick for transporting working portapotties at altitude? Does it need to travel vented?  I am concerned that a loaded portapotty might blow.

[beemerphile1]

I doubt it could blow.  Ours gets pressurized often when traveling through the mountains.  I have learned after arriving at our destination to open the flush valve with lid closed briefly to allow the pressure to equalize.  The first flush could create quite a splash if something is in the bowl.

[Malena]

Oh, I don't really think it'll blow, but I'm wondering how many inflation-deflation cycles it can take before the plastic cracks at a stress point.

When does one replace a potty? When it fails? Eww!

[ghacker]

Wow, there's a hazmat situation I never thought of. Thanks for mentioning it. Not a lot of altitude changes in the Midwest.

[wavery]

I doubt it could blow.  Ours gets pressurized often when traveling through the mountains.  I have learned after arriving at our destination to open the flush valve with lid closed briefly to allow the pressure to equalize.  The first flush could create quite a splash if something is in the bowl.

OOOOHHHH!!!! The visual effects.... EWWWWW!!!

[Malena]

I remember a post a while back asking about "potty blowback". I learned from that to crack it before using. But until recently we never had to crack it to slide it out of the cabinet. 

[wavery]

I remember a post a while back asking about "potty blowback". I learned from that to crack it before using. But until recently we never had to crack it to slide it out of the cabinet. 

If you use your PU in the mountains often, it probably wouldn't hurt to put a small pressure relief valve in the top of the lower tank, near the handle that you lift to empty it.

Something like this (just an example.... there are a million different kinds):
http://www.amazon.com/Lid-Pressure-Relief-Valve-New/dp/B003UHMKO4/ref=sr_1_33?ie=UTF8&qid=1345063731&sr=8-33&keywords=pressure+relief+valve

[AZbirddog]

I can't imagine walking around with a case of BLUE BUTT on a 2 week vacation

[Gumbie]

I heard jokes about blowing up the potty but what you describe is no joke. 
Thanks for sharing, I will be checking before using from now on. 

[Malena]

This is just a simple plain Thetford where opening the flusher valve is plenty pressure relief.

I think "potty blowback" is when one fills the upper bowl and then opens the valve to flush--there can be some uh turbulence. Usually one isn't seated at that point.  But we do crack it open a smidge before use. We have small children who are weirdly enthusiastic about flushing the portapotty and a little pre-draining of the bowl just makes for a tidier flush.

Anyway, we were pleased that the toilet instantly returned to its original shape and we didn't have to cut it out of the cabinet. The four-year old with the crossed legs was especially relieved.

[luv2campsum]

just leave the flusher valve open 1/4" and close the toilet cover