Black tank vent

[robertglines1]

We all agree! poo stinks ! so lets keep it from the inside of coach by all means. vent's good water traps /with water in them. A sealing valve on toilet. vent to inside bay I question some what but if you are sure the inside of coach has no way of sucking odor from bay area good: wire hole to bay   plumbing passage to bay   Basically anything air can pass thru.. I have thru roof and don't get smell going down road. But once in awhile someone holds the toilet valve open longer than necessary. Well everyone's poo stinks. We don't have the trap like the home units. we also don't use 3 gal of water per flush.    Bob

[Van]

Well done all! Great Thread

[luvrbus]

Where are the numbers he has numbers on his detector to measure ppm from 0 to 6500 I have a cheap one that does that



good luck

[Chaz]

 1.

[Van]

1 Poo per million? good deal!

[luvrbus]

I got a reading on the GM of 11PPM we added water it went to 700PPM stopped the water it fell back to 13PPM in less than 3 minutes, no air movement on a closed tank.
The S&S with the roof mounted vent was 824PPM steady never went up or down adding water, you don't need any thing fancy to test it with a CO detector will tell you we did that 2 lol the GM would not set it off till we ran water the S&S job would within 2 ft of the vent.
I don't care one way or the other how the guys vent their tanks the guy with GM laughed and said no reason I get no smell for about a week 

good luck

[Chaz]

Not sure I understand but, that's ok. I figure as long as i have air moving thru it, I'm good.

[bevans6]

The test is, using a tool similar to a propane detector, to determine if trapped methane is naturally being vented or eliminated from the tank.  what the test Clifford described showed is that the S&S with the correct roof vent constantly vented methane to the tune of around 800 PPM (this is the control in the experiment).  The GM conversion with a low vent did not release trapped methane constantly to any degree, showed by a static test of 11 PPM.  When they ran water into the tank to force displacement of gas, it rose to a level closer to what you would expect, 700 PPM, then rapidly declined to 11 PPM again.  Thus proving that the low vent does not vent methane from the tank continuously.

Methane gas is basically natural gas, the same thing (less the added smelly sulphur compound and being otherwise processed and purified) as the natural gas used in furnaces, stoves, etc, in many homes.  If you don't vent it, you are driving around with a tank full of natural gas, basically.  It has no smell, you can't tell it's there without a detector tool.  It would be fun to get a low vented bus and flush the toilet, or hold the valve open for a second, to see if methane gas comes into the bus from an improperly vented tank.

You can use a propane detector to test for methane because propane is basically a distillate of natural gas, which is mostly methane when it comes out of the ground.

BTW your theory that  as long as you have air moving through the tank you are OK is, sadly, false.  Methane is lighter than air so it can still get trapped in the high points in the system.  But you are probably getting rid of enough that the remainder isn't a true hazard.  If you decide to stay with what you have because it works well enough for you, then I have no issue with that.  The only thing I have an issue with is saying that it's the (or "a") right way to do it.  It's just not the right way to vent a tank.




Brian

[Chaz]

Thanx for the explanation Brian. That helped.
And I appreciate your not getting personal. I do believe my way is "a" right way to do it and as long as it is " getting rid of enough that the remainder isn't a true hazard" as my friend from Public Services ALSO says, I'm good with it.
And please note, I'm not telling people what to do. I didn't even do that when I owned my welding and fabrication business. I asked them to do jobs for me and if it was something I wouldn't do (i.e.  get this. True story.  -  weld on a turd sucker tank truck. How's that for irony!!??  ) then I would not ask them to do it either. That is fair and fairness is ALWAYS my goal. So I am merely suggesting to others what I have done and seems to work just fine. I never - and correct me if I ever do this - feel that I am the "end all, be all" on a topic. People are everyday, all day, coming up with new and better ideas for everything. And one of the ways that happens is they take an existing idea and work with it. My way my not be absolutely "spot on" but seeing how it does work someone may some how take it and expand on it to make the best way ever known to mankind!!!! Woo Hoo!!!  But as long as it does the job, I will tell others of it. It may "fit their bill" but they should also, ANYTIME you do something with a certain amount of hazard to it (electrical, plumbing, etc.) TEST IT even IF is it done to code. Mistakes... or in this case "sh*t happens". 
Thanx again guys,  and I will now let this rest. Too much time on a sh*tty subject.  (I kill me!  )
Chaz

[happycamperbrat]

Let's save the bus nuts some cash and instead elect people here (I put my vote in for Van cuz he needs to find the one to use for alternative fuel) to be the official black tank smeller  We could have a special rally and make bets and stuff!

[JohnEd]

Thanx again guys,  and I will now let this rest. (Chaz)...............Now, hold on there Pilgrim.  Not so fasty.  Not before I get to thank you for a most excellent post.  Had you not thanked Brian for his superb post I could have been the first to do so.  As it is, I will be the second...thanks, Brian.

John

[gus]

Just to clear up a few things here.

The vent in a house has nothing to do with sewer gas. As already posted, its sole purpose is to allow air to reenter the drain system when any liquid goes down it so it won't suck all the traps dry.

Now, back to buses. Methane gas inside a bus tank has no source of ignition unless you decide to light a match over your toilet so I don't consider that much of a problem. Never heard of one exploding or burning yet. (A disclaimer here, my 4104 has a bottom vent which works great and the toilet is on the opposite side from the tank which also works great.) In addition my waste tank feeds into the bottom which pretty much eliminates the interior sewer gas odor problem.

When a waste tank is emptied it is not pressurized,  a vacumn is created in the tank which can empty traps if the tank vent is too small, which can cause odors. Slower dumping or refilling the traps solves that problem.

[Ace]

Thank you Gus!   

[luvrbus]

Gus, vents on homes are for gases also, sewer gas has 7 different gases 3 of those will kill you methane gas is the least of your worry  hydrogen sulfide in sewer gas will send you home in hurry.
Check and see how many die from sewer gas each year I won't chance it but we do what we do as Fast Fred says do it your way


good luck

[JohnEd]

METHANE IS A LETHAL AND POISONOUS SUBSTANCE.  (just relax all you deep thinkers....a bullet is lethal but it isn't a poisonous "substance").  Methane, like METHANOL, destroys nerve cells and if you get a little too much it will blind you on the way to killing you.  This is no joke!  Sewer gas isn't a problem simply because it is explosive but because it can do irreparable harm to your body. When the canary in the mine quit singing that didn't just mean that there was going to be an explosion but that the air wouldn't support life at best and was poisoning you at worst and it wasn't even leaving a funny aftertaste.  Whe else would a grown up dirty sweat soaked bad tempered ultra male take a frigging little yeller bird to work with him?  It, propane, not the bird, though, facts be known a bird is also heavier than air, and it "sinks" when it exits the tank vent.  Sinking, it will puddle in depressions just like propane.  

I have personally had the good fortune and most interesting experience of laying in one of those "PUDDLES" , unbeknownst to me, in a 2 foot high crawl space under a house in the pitch dark night.  WAYYYY under that house and FARRRR from the entrance hole that was cut into the foundation and I could only return to by crawling backwards like a worm in a shallow ditch.  It was winter and I was wearing my Air Force Artic parka with the fur rimmed hood.  When the "WHOOOOOUMP" happened and all I could see was this wall of orange flame rushing at me I pulled up my hood  quicklikeabunny and held my breath.  Lost a lot of hair and eyebrows and eye lashes and I coughed a mighty spell.....but I lived thru it and I have witnesses to that fact.  I was laying in a ditch that had been dug, only because "CODE" required it I am sure, and I couldn't move right or left.  That ditch was to allow any small amt of leaking gas to flow out from under the house and thru the foundation wall  without pooling or puddling  Can you hear some guy extolling on the virtues of "discovering" new ways to do "stuff" and not digging that ditch?  I sure as hexx can and I don't even have to cup my ears to do so.  Now here is my bottom line:  I am at the head of the line of inventive folk that prides itself on being flex and creative and self-entertained.  But, when I hear something really stupid like running a gas relief line to the rear of the coach to vent and expanding propane, well, it just sounds so "GUMMINT INTERFERENCE" that I gotta take notice and ponder.  Vent my battery box at the top AND the bottom...what loon thought that one up to just waste my time....But then I remember the 6 volt bat that blew up in Vocational class and...  not everybody has had my ever so limited experience.  Those words "well that don't make any sense to me" are usually spoken with pride.  That's scary. What scares me more is that some fool will say he is completely flummoxed by something and without even pausing to  draw a fresh breath he launches into what we should do to correct a problem he doesn't understand and might not even exist, point of fact.  RR was famous for lines like "I don't know why we need a school lunch program for our prescious chill'n".  Then came the "follow me" moment of "so we are going to cut a serving of vegitables from the school lunch menu and save tax dollars".  And people cheered the confused old man that didn't understand, well, a lot of stuff actually.  It happens with frightening regularity.

If you need to deviate from the established rules then by all means do so and God bless.  But, deviation for the sake of it makes you a "deviate"  and you may well get more entertainment for your buck(pun intended)than you bargained for.  Low air in the fronts.

John