High altitutide hazard

MarkJ

Forum Member
We drove along the Route des Cretes at the Gorges du Verdon while we were in France two weeks ago, and made an "interesting" discovery.

The road goes up to about 1,200m above sea level and at this height the air is thinner. So much so that when I opened the sealed slider over the toilet container, having had a most satisfying wee, there was a degree of what you might call “blow back” as the pressure equalised. Fortunately not too messy, but a bit startling.
 

HTF

Forum Member
We drove along the Route des Cretes at the Gorges du Verdon while we were in France two weeks ago, and made an "interesting" discovery.

The road goes up to about 1,200m above sea level and at this height the air is thinner. So much so that when I opened the sealed slider over the toilet container, having had a most satisfying wee, there was a degree of what you might call “blow back” as the pressure equalised. Fortunately not too messy, but a bit startling.
Strange. My cassette, as soon as you insert it, presses a button to open a vent :unsure: There should be no pressure inside.
 

Millie Master

Forum Member
there was a degree of what you might call “blow back” as the pressure equalised. Fortunately not too messy, but a bit startling.

I have had exactly the same thing happen with my cassette!

I believe it might have been caused by the distinctly higher ambient temperature at lower altitude and then you went to 1,200 where the temp. was no doubt quite a bit lower, but the air inside the cassette would still have been at the higher temp achieved at the lower altitude.

Phil
 

Darcar

Forum Member
It’s a fairly common occurrence with cassette loos, when you chance altitudes.
It’s know as “Blue Bum“…

The cassettes are air tight so when you open them they either suck in or blow out, with the chance in air pressure..
 

HTF

Forum Member
As I mentioned before, my cassette has this valve that releases the pressure. When inserted in place, a little protrusion presses the button to vent the pressure, in my case to the underside of the van. Since I don't have a traditional cassette door since I mounted a sealed electric cabinet door which is on the inside of the van's back doors. When I mounted the system I wired a cable connection so that I could wire a small fan to force the air to the outside every time the toilet is flushed. After a few uses I don't feel the need to install the fan :p
images (6).jpeg
 

trevskoda

Forum Member
The trick is to fart at the same time you open the slide, this equels the pressure and no blow back will happen.
If after decending one must hold onto the dangly bits or you will be in trouble.:eek:😂
 
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Squiffy

Forum Member
We have a Dometic 4110 which has a plastic tube about 5mm id that is fitted through the floor to the outside under the van and the other end is attached to a nozzle that enters a reciprocal orifice on the cassette when the cassette is pushed home. This pipe directly allows any pressure built up in the cassette to void to the outer atmosphere under the van, which works of course vise the versa and so we don't suffer explosive regurgitation 🤣. Phil.
 

MarkJ

Forum Member
It’s know as “Blue Bum“…
🤣 Because I'd only done No 1s and not No 2s, I was bending over to pull out the slider, so I was lucky not to get "Blue Nose"
after descending one must hold onto the dangly bits
Never realised life on the road was so dangerous.
my cassette has this valve that releases the pressure.
Think that's posher than us. We have a Porta Potti, which has the benefit of being about the simplest toilet I could find - but it's doesn't have that sort of refinement!

However, it's not going to put me off going up high. Some fantastic scenery, views and light. Just got to be careful!
 

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