Preventing the explosion

[hensoa]

We used to have this problem but it was easily solved by removing and cleaning the automatic vent valve see item P(For the C2 cassette) in the manual.

The manual is available on this link http://www.thetford.com/HOME/CUSTOMERSUPPORT/ProductManuals/tabid/265/Default.aspx

click on Porta Potti Cassette C4 manual flush.

some of the other links take you to the wrong document.

[Frankkia]

The older cassettes suffered from this problem more than the new ones. It is caused by the fact that the cassette sealed - and if say the last time you used it was, say, at sea level and then you drove to higher ground (up an Alp) the difference in pressure would mean that as you opened the blade the higher pressure trapped in the cassette would forcibly eject the contents. The new cassettes have a "relief" (ok pun intended) nossle on the top which allows the pressure to stabilise.

 

A SOG is still a better way though for the other reasons I mentioned in the earlier post.

 

I've heard of toilet water but this is ridiculous :-D

[Mel B]

Don Madge - 2007-06-14 10:45 AM

 

Clive - 2007-06-14 9:41 AM

 

Our first explosion was when we were up a high French mountain contemplating joining the mile high club. Jan opened the trap and POW!

That curtailed any further thoughts on the subject in mind for some time.

 

But not since Pongo.

 

 

I bet it also curtailed the "Sudoku" for the day.

 

Don

 

Clive ... have you done it yet then at a 'mile high'?

 

 

 

 

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Played sudoku of course!!!! :D

[icelander]

Those self venting toilets may well vent into the interior of the toilet cubicle though. So SOG or Pongo or a tube vent for me is the way to go. Cold air in the morning when refitting cassette plus hot camper later - means expansion of air and explosion.

[Brian Kirby]

The vent is on the cassette, and it vents into the cassette holding compartment, which itself is externally vented.  If the seals on the toilet are in good condition, and working properly, and the cassette not over-filled, there should be no smell in the toilet compartment with, or without, SOG.

What the SOG is aimed at is eliminating the need to add toilet chemicals and, by enhancing the oxygen supply, to encourage aerobic decomposition of the cassette contents.  If the decomposition is aerobic the by-product is mainly CO2 and there is little pong.  In the absence of adequate oxygen the decomposition goes anaerobic, and the by-product much higher in methane, with resultant pongs.

The SOG clearly works, but it seems extremely expensive for what it comprises - even when compared to the cost, over its lifetime, of dosing agents.  There is an environmental argument, but there are dosing agents that claim to be environmentally friendly.  Ultimately, to me, this is a "lifestyle" decision and not really an economic, or an environmental, one.

[icelander]

Thanks Brian. There are no vents from my swivel bowl cassette compartment to the exterior. If I look at the back of the toilet cistern area where it meets the wall - I can see light when the external compartment door is opened (Knaus 500). Where or how are the vented ones vented?

[Brian Kirby]

Via incomplete door seals.

[Bazhornet]

I know I'm a bit behind here, but have been away for a couple of weeks. I have looked at a SOG and have worked out that I will get my money back within 6 months of typical usage thru not having to buy chemicals (you wouldn't believe the bowel movements of 3x 8yr old boys plus a 10yr old girl!!!).

However, whilst I consider myself relatively competent DIY style - although I would check, check, then check again before drilling ANY holes in my 'van - my query is with the electrics. What exactly am I to tap into as I cannot see any obvious wires when peering into my cassette space?

Baz

[Clive]

Remove the casette, bend down and look up at the roof of the enclosure.

You should find a few wires, the odd fuse etc. This is where I tapped in to connect PONGO. I expect SOG to be quite similar.

 

Have a look half way down the page on this link for this view

 

http://www.motts.dsl.pipex.com/Pongo.htm

 

C.

 

[Bazhornet]

Clive,

I am certainly impressed with your innovative approach! I'm alsmost certainly going to buy a SOG, so if I get stuck I'll give you a shout.

Baz

[Clive]

No problem,

I would like view of the instructions SOG supply with their kit if possible.

 

C.

 

[Peter Pan]

Icelander

 

I have heard that if you place a dead rat in a septic tank it speeds up the decomposition process. You could try this in your toilet cassette. I cann't guarantee it will work but it would be a cheap alternative to chemicals or electrical devices. ;-)

[Clive]

Have you ever smelt a fermenting deat rat Yuck!

 

[Brian Kirby]

I think it's a matter of scale.  If rat = septic tank, perhaps dormouse = Thetford cassette?  Thing is, you'll need to put in a new one every time you empty the cassette - so you'll need to take a supply with you, so - lots of mouse cages to add to the payload.  Nah - I think this just got toooo complicated by half!

[Mel E]

A few observations:

 

1. We are new to cassettes (always had holding tank loos) and fitted a SOG. It keeps smells out of the bathroom, but that, in my experience is ALL it does.

 

2. The stuff about extra oxygen causing decomposition is surely wrong? Even with only two people the cassette is full within about 3 days and half of these contents are only 1.5 days old - far too soon to expect any significant decomposition.

 

3. There is, however, a very strong smell when emptying the cassette - the sort of smell you get in badly serviced public loo. If you are in a queue at a campsite, be prepared for the others to walk away. You may still want to add chemicals to prevent this!

 

4. I believe that all loo chemical additives no longer contain formaldehyde. I think they only contain smell masking chemicals, none of which should affect decomposition in a septic tank. I think the septic tank thing is a throwback to formaldehyde days, but I will check this.

 

Mel E

====

[Brian Kirby]

Mel speak much wisdom!  Don't have SOG, so have only read advertiser's puff.  I have noticed some cassettes are a bit overpowering when others empty them, but it wasn't the aerobic or anaerobic bacteria, it was the other stuff!  Ours always smells far less.  We've always used Thetford Green in ours, but we use sites, so don't fill the cassette in 3 days.  Is there a hidden cost in not using sites, through the enhanced cost of toilet dosing?  We seem to manage around 10 weeks with only one of the small Thetford containers for dosing at around 50% the recommended rate.  This seems generally satisfactory in practice.

[Mel B]

Brian Kirby - 2007-06-21 5:25 PM

 

We seem to manage around 10 weeks with only one of the small Thetford containers for dosing at around 50% the recommended rate.

 

Wow - that's one mighty toilet cassette Brian!!!! :-S

 

 

[Brian Kirby]

Mel B - 2007-06-21 9:10 PM

Brian Kirby - 2007-06-21 5:25 PM We seem to manage around 10 weeks with only one of the small Thetford containers for dosing at around 50% the recommended rate.

Wow - that's one mighty toilet cassette Brian!!!! :-S

Now pay attention, Mel, it was the Thetford chemical container I was talking about, not the cassette! 

Still, another effluent saving comes to mind.  Some of us could pee into the bottle, and dispose accordingly. However, this proposal may not suit us all!  Do not attempt this at home!  :-)

[Thai Bry]

Still, another effluent saving comes to mind.  Some of us could pee into the bottle, and dispose accordingly. However, this proposal may not suit us all!  Do not attempt this at home! 

Brian,

Thank you, thank you, very very much  you've now solved a mistery of mine after all these years. As when I first came to England I saw a product called "Yellow Lemonade" made by a local company in Huddersfield called Ben Shaw. It did not sell as well as the normal white lemonade. Now I know why!!

Thank you once again.

Thai