Blackwater tank vent

Elliot Naess · 10-11-2008, 03:11 PM

Good topic, specially since I need to make a decicion on my own vents.

I don't know anything about charcoal filters, but I do know something that kills odors very effectively, and that's the chemical that is sold for that purpose. One ounce of treatment per ten gallons of tank, and there is simply NO smell. I just removed and reinstalled my commode -- and did not notice any indication that the tank immediately below my nose was close to full. I use Thetford Supreme Green Holding Tank Deodorant, which is bioderadable and free of the old formaldehyde-boogaboo. When I read horror stories about stinky tank fumes, I just shake my head.

That said, I don't doubt that whatever wafts out of such a tank may not be as well suited to breathe as pure air, so I've been using a vent pipe to roof level. But it's a quick-n-dirty external pipe, and it is far too ugly to keep that way.

So I'm thinking like you are; how about simply venting below the floor? Well... the top of the tank is just below the floor, so there would be a splash-out problem. We would have to run a pipe up a couple of feet, then back down. A couple of zig zags on the way up would be a good idea also. I suppose such an arrangement could be hidden inside a wall or something. But I suspect liquid could splash mighty high in a moving vehicle, even with some kinks in the pipe, specially when, say, 70 gallons of the stuff gets to gallopping from one end of the tank to the other.

Now.... somewhere here, I have the "building code" for RVs. Let me look at that....

Elliot Naess · 10-11-2008, 03:55 PM

Well, the NFPA 1192 Standard on RVs, 2005 edition, seems to say that all vents must go thru the roof. And like Smitty says, ten feet of pipe is cheap enough.

Under "Body Waste Holding Tank", they require an "individual" vent pipe thru the roof, which sounds like it means that we should not combine black and gray vents.

And as for holding tank vents in general, they mention only Roof Vent Termination -- no other option.

To what extent this code applies to our conversions... each of us must decide for himself. The NFPA seems to say that their RV regulation are advisory only, but I think we would do well to heed such professional advice based on decades of experience. Within reason, of course. There will always be compromises that are perfectly acceptable for you or me, but not for a paying customer who expects his RV to operate just like his house at home.

Elliot Naess · 10-11-2008, 08:12 PM

Oh, sorry. "They"... is the National Fire Prevention Association. Ever since I bought that one booklet from them a couple of years ago, they have been trying to get me signed up as a member -- to the tune of something like $135,- a year. They must think I run an RV factory. I don't know much about them, but it's surely a good thing that somebody bothers to gather lots of safety related information that has been learned over the years in one booklet for easy reference. And they have been at it since 1937, so they might even know something I haven't learned yet.

That said, I wouldn't invite them to study Millicent real closely either.

wmah · 10-12-2008, 12:05 PM

I vented my black tank out the side of the bus. I don't notice any unpleasant smells. I do use the blue chemical that is for the purpose. I did the under floor vent for the gray water, well almost, the pipe from the shower drops into a over sized hole that provides the vent.

lapeer20m · 10-12-2008, 09:57 PM

Quote:

Originally Posted by Elliot Naess

Oh, sorry. "They"... is the National Fire Prevention Association.....

That said, I wouldn't invite them to study Millicent real closely either.

it's technically the "National Fire Protection Association (NFPA)" but who really cares....

I didn't even know they covered things like vent pipes in RV's. The create the standards that fire departments feel obligated to follow. The way it works in the fire service is that NFPA standards are not requirements, only "suggestions"....until a lawsuit happens. Pretty much every fire dept in america strives to comply with all nfpa standards.

how any of this really affects skoolie owners i'm not sure. doesn't seem like your vent pipe is likely to cause any sort of litigation. if you had a propane tank not installed in compliance with nfpa and it caught fire and injured or killed people then the lawyers that's another story.....

Elliot Naess · 10-12-2008, 10:27 PM

Quote:

...Protection...

I was looking right at the booklet, reading "protection" and typing "prevention".

No more for me, thanks -- I'm typing! (urp)

Redbear · 10-13-2008, 03:25 PM

Quote:

The way it works in the fire service is that NFPA standards are not requirements, only "suggestions"....until a lawsuit happens. Pretty much every fire dept in america strives to comply with all nfpa standards.

NFPA also writes the National Electrical Code, which electricians use to determine wire sizes, grounding, how many wires in a junction box, etc. etc.
(In other words, everything.)

In most places these are NOT voluntary requirements. The state/local jurisdictions may not adopt the latest book right away when it comes out every few years, but let a lawyer find out there is a better standard than the one you referenced and watch out!

GoneCamping · 10-18-2008, 08:32 PM

Quote:

I think underbus venting with charcoal filtration is the way to go

If this were true you'd see other people doing it, not to mention the RVIA would adopt it too. I'll stick with venting through the roof, 10' of pipe and vent cap is a lot cheaper than a filtration system (which by design must have mainentance once in a while, even charcoal will stink after it absorbs enough of it).

BTW, the "individual" roof venting I would think means per tank, commercially built RV's (including the 2004 model I just sold) use seperate vent stacks for each tank. JHMO...

Russell · 03-04-2009, 02:58 PM

Ive hang'n my black water tank at the present time and I must say the thought of going through my roof with a vent go's against the grain a bit. I ve studied this for some time and figured that if it could be done another way the R.V. builders would do it another way. I don't like the idea of cutting a hole in my roof, sounds like a leak to me.

colliervilledave · 03-04-2009, 07:32 PM

On my gray water .. I side vented thru a bench seat then out the side..The black water i didnt vent at all..push the flapper every thing drops in when draining at a dump i prop the flapper its drains fine..I keep chem tabs in the tank no bad oder...the gray tank first trip out no vent the sink backed up in the shower..duh...it got side vented first thing...is my black water not vented going to come back and bite me..

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