Vent odor

Peggie Hall HeadMistress · Aug 31, 2011

Why do so many people think urine doesn't stink?

When urine OR solids--OR sea water, or garbage or any other organic material--breaks down anaerobically, it creates the same hydrogen sulfide and sulphur dioxide gasses that solid wastes create...gasses that STINK.

And your tank IS anerobic...the vent line may have a large enough diameter, but it's way too long, isn't straight, isn't horizontal enough to allow the exchange of air needed to keep the tan aerobic...and you're not using anything in the tank to help it.

That you didn't have any odor in the boat at all says the source of your odor isn't stagnant sea water trapped in the intake..you'd have smelled that BIG time in the bowl with the first flush.

You said, "this year I tried a chemical you put into the intake hose. http://www.tankette.com/ Couple of people recommended it but I'm not sure if it's working or not."

What else besides the odor out the vent do you need to tell you whether it's working or not? It's not a tank product btw...but can interfere with tank products. I don't recommend it or any other intake inline chemical. Some even use chlorine, which is highly destructive to the rubber parts in toilets and breaks down hose resistance to odor permeation.

There's been a lot of discussion about holding tank odor in this forum over the years...you'll learn a lot about what causes and how to eliminate it you'll spend some time reading some of those discussions. You might also find the information at the link in my signature useful.

Meanwhile, pump out and THOROUGHLY flush out your tank...and then use a tank product called Odorlos ACCORDING TO DIRECTIONS. That should help quite a bit.

Cayennita · Sep 1, 2011

Run a hose from the vent to the outside, similar to an overflow for water or diesel or antisiphoning line for the engine. That way the smell will stay outside the boat.

Peggie Hall HeadMistress · Sep 1, 2011

Venting to the outside is not optional, it's required!

Cayennita said:
Run a hose from the vent to the outside, similar to an overflow for water or diesel or antisiphoning line for the engine. That way the smell will stay outside the boat.

Apparently you are not aware that marine sanitation regulations in the US and most other countries REQUIRE that all waste tanks be vented to the outside of the boat because methane is flammable. And also because the gasses that stink--hydrogen sulfide and sulfur dioxide--are also highly toxic, even lethal in high enough concentration.

Vent lines on ANY tank should never be considered "overflows"...nothing should flow through them but air...which is why vent lines are sometimes called "breathers" in the UK.

As for eliminating the smell...I suggest that you also spend some time reading the discussions in this forum to learn how to PREVENT odor from occurring in the first place...eliminating any need to route the vent away from people. And you may also find the link in my signature to be useful.

And btw...I see you've just joined our merry little band today... Welcome aboard!

Peggie Hall HeadMistress · Sep 1, 2011

Define "proper"....

Tank vents in general have two main functions: 1. to provide a source of air replace contents--fuel, water, waste--as they're pulled out...without which whatever is attempting to pull contents out will pull a vacuum than prevents anything from being removed. 2. to provide an escape for air displaced by incoming contents and any expansion gasses...without which the system would become pressurized. Water and fuel only have to be HELD in tanks...so that's all that vents on water and fuel tanks need to do, so any routing that allows those two things to happen is "proper." But waste that's held aboard--if it's to be tolerable to the people aboard AND anywhere within a 50' radius of the boat--also needs to be managed in addition to being held, giving waste tank vents a third function: to provide the VENTILATION that creates the aerobic condition in the tank that's necessary to prevent odor. Is there anything IMproper about waste tank vents that don't ventilate too? No...any vent that provides a source and an escape for air in the tank is a "proper" vent. It just makes being anywhere it unbearable.

Your boat is a Catalina...and Catalina is--or was--the only boat builder who runs vent lines into rail stanchions that have only tiny little holes or slits in 'em. That works ok for water and fuel, but is a nightmare on holding tanks...'cuz those little holes/slits don't begin to provide enough air exchange and they also clog up if you so much as spit at 'em. So if your vent line ends up in a rail stanchion, you'll have a huge improvement if you reroute it to a new thru-hull.

As for two vent lines...might help...might not. I'd bet it wouldn't be necessary to run 'em both the same way...in fact, I'd bet we could reroute yours if you're willing move the thru-hull. If you'd like to do a little brainstorming, email me.

robertsapp · Sep 2, 2011

Peggie, I made this comment in another discussion thread, but now I can't find it so I'm sorry if you've already answered it. Has anyone ever thought to build some sort of small fan, maybe an axial flow design that could fit in a vent line, that could continually push fresh air into a holding tank? Make it solar powered so it didn't consume battery power. You'd need a second vent line to allow for proper air exchange. Bad idea?

Peggie Hall HeadMistress · Sep 2, 2011

Inline fans are not a new idea...

And it can work. But it does require two vent lines and the fan should PULL air through the tank instead of pushing it...so it needs to be an exhaust fan. Years ago Nicro approached me about adding just such a fan to their product line...but we came to the conclusion that there isn't enough need for it, and therefore not enough of a market for it, to be profitable to design and tool for it.

I know of owners who've cobbled up their own one-offs using computer muffin fans. Those fans aren't designed to withstand that kind of corrosive environment, so have to be replaced at least annually...fortunately, they're cheap.

Aerating the contents is a better solution...and that's not as easy as most people think. If it were, the Groco Sweetank system Groco Sweetank installation instructions wouldn't still be the only one on the market 10 years after they introduced it.

Peggie Hall HeadMistress · Sep 2, 2011

You've obviously lived a VERY pampered life that doesn't include children, pets or housekeeping.

.

Stu Jackson · Sep 2, 2011

Peggie Hall-HeadMistress said:
You've obviously lived a VERY pampered life that doesn't include children, pets or housekeeping. .

Children!?! I got a college graduate - ya don't wanna know....:cry:

thinwater · Sep 2, 2011

And for a differnt point of view....

a. In a corrosive tank, blow, never exaust unless there is a very special reason. The fan will last longer (no corrosion or explosion hazard) and there is NO difference in the efficiency of air movement. Why no difference? Both streams are introduced through pipes and there is no way the tank can tell whether it is pushed or pulled. Multi-million dollar chemical equipment companies will confirm this. If there were many inlets (perhaps a house or boat or a cooling tower with louvered sides) the answer is different. This is one of the reasons the Sweet Tank equipment holds up; they push instead of pull.

b. I think we will agree that the Sweet Tank system is primarily for large tanks (over 50 gallons perhaps). Smaller tanks can be managed with ventilation and the bubbling will not help (I've been running side-by-side tests).

c. There are other chemicals. Oderlos is among the best in a well-ventilated tank, and others are effective with less air. Vanish Odor can be pretty impressive. There are also some terrible chemicals out there (containing formaldahyde typically) that have been on the market for over 10 years and need to leave. They don't work and are just nasty. But the weakness of all chemicals is that you have to remmember and you have to treat nearly every week. Like that's going to happen (it doesn't for me).

d. A vent filter is also simple and cheap when considered over a few years. Odor control is more complete than any other method, even if the staunchian is at your ear. There are installation concerns--all failures I've heard of were easily avoided--but nothing that a savvy DIY can't figure out.http://sail-delmarva.blogspot.com/2011/04/holding-tank-vent-filter.html. The down side? Solids build-up can be greater than a good ventilation/chemical aproach.

And I think we can all agree that venting through a railing is mental. What were they thinking? The chance for plugging alone, if not simply the nose-proximity issue.

Peggie Hall HeadMistress · Sep 2, 2011

Exhaust for a good reason...

a. You're assuming that an inline fan is the only way it can be done...it's not. And it's far more efficient to PULL air through than push it through.

An exhaust fan can be installed on the outside of the hull, to replace one of the vent thru-hulls..but doesn't work too well on a fan that blows air in, especially if a vent line that isn't straight is one of the main reasons for installing a fan.

b. Apparently you haven't talked with Groco about the Sweetank....if you had, you'd know that 40-50 gallons is about the UPPER limit that a single unit can handle effectively. That's also about the minimum size that it makes sense to install one, so the "window" is pretty narrow.

c. There are only two tank products that I recommend: Raritan K.O. which requires a source of oxygen to function aerobically...and Odorlos, which needs a lot less oxygen to function aerobically, but still cannot do so in an anaerobic (septic) environment.

d. Filters only treat the symptoms, they not only don't solve the problem, they help to create it. Installing a filter to eliminate holding tank odor can be compared limiting the treatment of someone who has a ruptured appdendix to giving them a prescription for pain pills.

e. Venting water and fuel tanks through small holes in the aft side of a rail stanchion on a sailboat actually makes a lot of sense...'cuz it keeps sea water from getting into the tanks via the vents when the boat is heeled enough to put its rails in the water. When it became necessary to install holding tanks, it never occurred to builders--or very many others in the marine business either--that while water and fuel only need to be HELD, sewage also has to be managed...so the industry simply vented holding tanks the same way they'd always vented water and holding tanks...even using the same vent thru-hulls on all of 'em. Problems with holding tank vents weren't the builders' problems, they became owner/maintenance problems...and for the most part still are, 'cuz builders continue to do what they've always done--whatever's easiest and keeps their costs down.

And I'm glad they did...'cuz if they'd given ANY thought to onboard sewage management when all this started, there'd never have been what turned out to be a very good business opportunity for me! :dance:

thinwater · Sep 3, 2011

Peggie Hall-HeadMistress said:
a. You're assuming that an inline fan is the only way it can be done...it's not. And it's far more efficient to PULL air through than push it through.

An exhaust fan can be installed on the outside of the hull, to replace one of the vent thru-hulls..but doesn't work too well on a fan that blows air in, especially if a vent line that isn't straight is one of the main reasons for installing a fan.

b. Apparently you haven't talked with Groco about the Sweetank....if you had, you'd know that 40-50 gallons is about the UPPER limit that a single unit can handle effectively. That's also about the minimum size that it makes sense to install one, so the "window" is pretty narrow.

c. There are only two tank products that I recommend: Raritan K.O. which requires a source of oxygen to function aerobically...and Odorlos, which needs a lot less oxygen to function aerobically, but still cannot do so in an anaerobic (septic) environment.

d. Filters only treat the symptoms, they not only don't solve the problem, they help to create it. Installing a filter to eliminate holding tank odor can be compared limiting the treatment of someone who has a ruptured appdendix to giving them a prescription for pain pills.

e. Venting water and fuel tanks through small holes in the aft side of a rail stanchion on a sailboat actually makes a lot of sense...'cuz it keeps sea water from getting into the tanks via the vents when the boat is heeled enough to put its rails in the water. When it became necessary to install holding tanks, it never occurred to builders--or very many others in the marine business either--that while water and fuel only need to be HELD, sewage also has to be managed...so the industry simply vented holding tanks the same way they'd always vented water and holding tanks...even using the same vent thru-hulls on all of 'em. Problems with holding tank vents weren't the builders' problems, they became owner/maintenance problems...and for the most part still are, 'cuz builders continue to do what they've always done--whatever's easiest and keeps their costs down.

And I'm glad they did...'cuz if they'd given ANY thought to onboard sewage management when all this started, there'd never have been what turned out to be a very good business opportunity for me! :dance:

I know this is your column, but there is one bit of misinformation here, regarding (a).

a. Incorrect. First, there is no difference in efficiency, (push vs pull) on a tank served by 2 pipes. A house with many windows is completely different. Please contact an engineer or the local university if you feel the need to continue distributing this advise. I design such systems and I am certain there is no mathematics or quantified expereince to support the assertion; once the air is columnated by the hose at each end, the flow patterns are necessarily identical, as required by conservation of mass and momentum. Second, we both know that the Coast Guard requires all electrical equipment exposed to holding tank fumes to be hazardous location rated. We know that the gases in a holding tank are both corrosive and potencially explosive. Thus, any mention of exhaust fans on holding tank vents is ill advised from a regulatory/insurance view point, and is against common sense.

b. Yup. Odd.

c. Unfortunately, it would be too much to ask for vendors to point out such information about applicability. One-size-fits-all sells better.

d. I stated my experience, including the fact that filters do not break down solids in the way that enhanced ventilation and some chemicals do. The solids build up is not worse than it was with the factory vent line, which was quite short (less than 30 inches, 3/4-inch). I am not selling anything and I was not stating opinions, only observed facts, both pro and con. Do I believe (opinion) that a vent filter is the correct solution in every or even most cases? No. However a stanchion vent is an interesting candidate.

e. Yup.

Peggie Hall HeadMistress · Sep 4, 2011

When it comes to tank products...

One size fits all has nothing to do with what sells...price drives sales. The "active ingredient" in 90% of tank products is one of three chemicals: formaldehyde, gluteraldehyde, or quanterary ammonium compounds, which cost a fraction of what it costs to produce live bacteria, enzyme and other environmentally friendly products such as Odorlos. Which explains why Thetford sells more tank products to the marine and RV markets than all the rest combined.

"Biodegradable" is a meaningless feel-good term...formaldehyde is biodegradable. If what you're dumping into the water every time you use your macerator pump matters to you, read the MSDS for your tank products some time. Easier yet, just read the first aid warnings on the packaging. If they say something like "harmful or fatal if swallowed, may cause blindness, call poison control immediately" there's nothing "environmentally friendly" about it! But hey...it IS the cheapest!

thinwater · Sep 4, 2011

Peggie Hall-HeadMistress said:
One size fits all has nothing to do with what sells...price drives sales. The "active ingredient" in 90% of tank products is one of three chemicals: formaldehyde, gluteraldehyde, ... ... If they say something like "harmful or fatal if swallowed, may cause blindness, call poison control immediately" there's nothing "environmentally friendly" about it! But hey...it IS the cheapest!

This, from WIKI (but the same information is easy to find elsewhere):
___________________________

FEMA trailer incidents

[edit] Hurricane Katrina & Rita

In the U.S. the Federal Emergency Management Agency (FEMA) provided travel trailers and mobile homes starting in 2006 for habitation by residents of the U.S. gulf coast displaced by Hurricane Katrina and Hurricane Rita. Some of the people who moved into the trailers complained of breathing difficulties, nosebleeds, and persistent headaches. Formaldehyde-catalyzed resins were used in the production of these homes.
The United States Centers For Disease Control and Prevention (CDC) performed indoor air quality testing for formaldehyde[53] in some of the units. On February 14, 2008 the CDC announced that potentially hazardous levels of formaldehyde were found in many of the travel trailers and mobile homes provided by the agency.[54][55] The CDC's preliminary evaluation of a scientifically established random sample of 519 travel trailers and mobile homes tested between Dec. 21, 2007 and Jan. 23, 2008 (2+ years after manufacture) showed average levels of formaldehyde in all units of about 77 parts per billion (ppb). Long-term exposure to levels in this range can be linked to an increased risk of cancer and, at levels above this range, there can also be a risk of respiratory illness. These levels are higher than expected in indoor air, where levels are commonly in the range of 10-20 ppb, and are higher than the Agency for Toxic Substance Disease Registry (ATSDR, division of the CDC) Minimal Risk Level (MRL) of 8 ppb.[56] Levels measured ranged from 3 ppb to 590 ppb.[57]
FEMA, which requested the testing by the CDC, said it would work aggressively to relocate all residents of the temporary housing as soon as possible. Lawsuits are being filed against FEMA as a result of the exposures.[58]

____________________

If 8 ppb is all that is required to reach EPA action levels, and there are about 40,000 grams of air in the occupied volume of a 35-foot boat, that means a spill of 0.0003 grams would be over the EPA threshhold. Just taking the lid off the bottle might get you there, when the boat is not well ventilated.

It makes no sense, to me, that they even sell these products for use in confined spaces. They don't even work well. Done.

thinwater · Sep 4, 2011

Does Oderlos contain anything other than sodium nitrate?

http://www.yara.us/doc/34198_OdorlosDryMSDS.pdf

Effective, yes. Expensive ingredients, not at all. But I respect simplicity, when it works.

Peggie Hall HeadMistress · Sep 4, 2011

The ingredients are listed in the MSDS. It's also available in liquid form.

As to the cost, that's relative. An ingredient that costs "only" a dime would seem to be inexpensive unless you're competing with a product that only costs $.02 to produce. (That's just an illustration, not intended to represent the actual cost of anything.)

thinwater · Sep 4, 2011

MSDSs are only required to list hazardous chemicals.

Peggie Hall-HeadMistress said:
The ingredients are listed in the MSDS. It's also available in liquid form.

As to the cost, that's relative. An ingredient that costs "only" a dime would seem to be inexpensive unless you're competing with a product that only costs $.02 to produce. (That's just an illustration, not intended to represent the actual cost of anything.)

Many mild chemicals and enzymes do not require listing. Thus, an MSDS is a source of hazard information, not product specifications.

Regarding the Groco Sweet Tank system and air pump sizing, based upon one telephone conversation and EPA evaluation, the 50-gallon upper limit of a single pump is solely to insure rapid decomposition if used as part of a Thermopure system. For odor control, I think it would easily mange twice that, based on the minimum flow require to provide nominally aerobic/anoxic conditions. It would like provide far more oxygen transfer, because of sub-surface injection, than any passive system. Thoughts?