Holding tank vent line

[HeadMistress]

RickB wrote:Except for the fact that those tiny little filters are prone to clog very quickly, I can't imagine why anyone would object to having a vent filter installed.

I just wish I'd invented something that creates the very problem it's sold to solve...'cuz that's what a vent filter does by impeding the flow of air exchange that's needed to keep a tank aerobic.

And you're absolutely right that there is no reason any boat has to smell like a sewage treatment plant...or anything else.* But vent line filters only treat the symptom--and for a RIDICULOUS price!...they don't cure the problem.* Three of the d'd things just about pays for an aeration system that DOES cure the problem! But even that much isn't needed if the ventilation air flow through the tank can be improved enough..which it can be in most cases.

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[RickB]

HeadMistress wrote:I just wish I'd invented something that creates the very problem it's sold to solve...'cuz that's what a vent filter does by impeding the flow of air exchange that's needed to keep a tank aerobic.

Here we go again ...* how do you expect a 1/2 or 3/4 inch vent line to provide a "flow or air exchange" between the world and the black tank?

The vent line is like a reversible express lane, it vents stink out when a head is flushed and (hopefully) it admits air when the tank is pumped out. That is all it can do. If you have disovered some new kind of gas laws or previously unknown physical phenomenon it needs to be peer reviewed and published, there's a Nobel waiting.

Ridiculous price is correct. The market for those consumer devices is a rip off in nearly every respect because of the voodoo surrounding marine sanitation. A very effective filter can be assembled from the plumbing aisle at Home Depot and filled with media available online in bulk. And I am not talking about some Florida swamp shadetree workaround, this exactly duplicates the filters sold for use on commercial vessels and large yachts.

Here is an example of one and the zeolite/carbon media that you can buy in bulk from several sources to replace inexpensively.

http://www.sweetfilter.com/

 

[motion30]

HeadMistress wrote:
One doesn't install a filter. If the larger vent line can't supply enough air exchange, an aeration system is the best solution...the Groco Sweetank system costs about the same amount as 3 filters.

http://www.groco.net/SVC-MAN-07/Sec1/pdfs/STK.pdf

* Peggy

*i just ordered your book**Get it in a week* but from what I am understanding* I need a 1.5'' vent line with no filter* Thats it* problem solved?

 

[HeadMistress]

The vent line is like a reversible express lane, it vents stink out when a head is flushed and (hopefully) it admits air when the tank is pumped out. That is all it can do..

That's NOT all it can do, when it's installed correctly.* I didn't invent anything...only learned how to apply the same laws of physics that apply to all organic matter to onboard waste management. And I learned those from biochemists and sewage treatment experts.

Here we go again ...* how do you expect a 1/2 or 3/4 inch vent line to provide a "flow or air exchange" between the world and the black tank?

I don't.* For it to work the vent line needs to be 1"--1.5" or even larger is better, but there IS a limit to the acceptable size of a hole in the side of a boat! And the line has to be straight, 5' or shorter, and rise no more than 45 degrees.

If the vent line can't meet all of those requirements, mechanical intervention--aeration or two vents with an exhaust fan in one--becomes necessary. The main impediment to making it work are builders who never give any thought to tank location...putting water tanks in the best place for a waste tank and then putting the waste tank in a location that would be just fine for water, but not for waste management.

 

[HeadMistress]

motion30 wrote:Peggy i just ordered your book**Get it in a week* but from what I am understanding* I need a 1.5'' vent line with no filter* Thats it* problem solved?

*Maybe...maybe not. There are other factors (see my reply above this one). I'll be glad to work with you to figure out what IS needed to solve the problem.

 

[motion30]

HeadMistress wrote:motion30 wrote:Peggy i just ordered your book**Get it in a week* but from what I am understanding* I need a 1.5'' vent line with no filter* Thats it* problem solved?

*Maybe...maybe not. There are other factors (see my reply above this one). I'll be glad to work with you to figure out what IS needed to solve the problem.

That would be great** What do I need to know to get started

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[RickB]

Old Stone wrote:Hmmmmm..............Gettin' close to being just borderline disrespectful.

It is not borderline.*It means I have zero respect for voodoo engineering and people who publish nonsense.

I am still waiting to learn how even a 1.5 inch x 4.9 vertical vertical tube is going to facilitate a simultaneous bi-directional flow of gases. The gases normally associated with stink are (except for ammonia) heavier than air.*

The only truth that has been posted here aside from my disrespect*for the claim that some kind of natural draft bi-directional flow occurs in the 1/2 or 3/4 inch vents installed on*nearly all off-the-shelf*holding tanks, is the suggestion that aeration is the best way to avoid anaerobic stink.

 

[HeadMistress]

I am still waiting to learn how even a 1.5 inch x 4.9 vertical vertical tube is going to facilitate a simultaneous bi-directional flow of gases...

A VERTICAL tube of any size won't...I've never said it would. What part of* "short, straight, doesn't rise more than 45 degrees" didn't you understand?

I have zero respect for voodoo engineering and people who publish nonsense.

The TRUTH is, you just refuse to believe that any mere woman could know what she's talking about! :nana:

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-- Edited by HeadMistress on Monday 25th of July 2011 11:20:52 AM

 

[HeadMistress]

motion30 wrote:HeadMistress wrote:motion30 wrote:Peggy i just ordered your book**Get it in a week* but from what I am understanding* I need a 1.5'' vent line with no filter* Thats it* problem solved?

*Maybe...maybe not. There are other factors (see my reply above this one). I'll be glad to work with you to figure out what IS needed to solve the problem.

That would be great** What do I need to know to get started

*Send me an email.

 

[RickB]

HeadMistress wrote:The TRUTH is, you just refuse to believe that any mere woman could know what she's talking about! :nana:**

*Now who is being a silly sexist?

Prove my points wrong if you can,*convince me that*yours are *correct if you can*but don't think that playing the sexism*card*is going to get you anywhere but down the toilet. Stick to the facts if you can. You will have to work really hard to restore any credibility after that statement. It*belongs in OTDE and not here.

My*"chief mate"*is a licensed chief engineer of steam and motor vessels and has sailed*on her license on both motor and steamships*for years.*She has also*sailed as chief engineer on very large yachts. She has as many years sailing as a licensed*engineer, including maintaining marine sanitation systems, as you claim to have*talking about*heads.*

I can almost guarantee that she has more time keeping an MSD system operating correctly at sea than you have onboard a boat of any kind doing anything. When she talks about marine engineering, including sanitary systems, I listen respectfully because she earned her stripes and I have watched her work, including rebuilding the system on our own 48' trawler, a 65' converted tug, and our little 34' CHB.

 

[mdyer]

Peggy, I spoke with you about a month ago with the problem of a "too large" holding tank of 250 gallons and a 1/2" vent line that is about 10 feet long and rises (not in a straight line) about 5'. I have been searching for large enough hru hulls that I can use but came across a "Lil Stanker" in-line 1 1/2" 12 volt fan. What do you think of tapping into the top of the take at the opposite end for a second vent line, installing the in-line fan and syncing it to run when either one of the Vac-U-Flush heads is pumping.

 

[HeadMistress]

It COULD work...but only if it it's an exhaust fan and runs 24/7/365 (except during any extended layup, of course). However, if your tank is much deeper than 18", aeration may be the only answer...'cuz 18-20" is about the max depth that can be kept aerobic using passive ventilation above the the surface. 250 gallons is a LOT of sewage--a lot of WEIGHT (over a ton!)--to try to manage. We can brainstorm some ideas if you'd like to send me an email.