how to properly 'soft couple' pvc to hose

[phantomracer]

Had a question related to the thread I started http://forums.sbo.sailboatowners.com/showthread.php?t=113005

I plan on having a few pieces of rigid PVC in the system. I am planning on coupling them with 1.5" hose I just bought (trident white) at the Defender sale (great deal on trident remnants there!!) ..

Would I use 1.25" pvc schedule 40? and just clamp the hose to the pvc? Is there anything else I need (sealant, etc) and any other best practices when joining hose and pvc?

This is my current plan (incorrect pic, see my next message)

Thanks

Paul

 

[Peggie Hall HeadMistress]

Not what you need to do

If I understand your drawings correctly, the only place you want to use hard pipe is the tank pumpout line. For that, you can connect the hard pipe directly to a 90 tank fitting...then switch to hose above the top of the tank.

Plan B: Put the tank discharge fitting on the top of the tank with a pickup tube inside the tank. That will also be hard pipe...easy to do.

After reading some of your previous thread, I think we prob'ly should talk. It'll be a lot easier than all the typing that'll be required. Send me an email (just click on my name next to this post to do that)? Once we get you sorted out we can post the "results" here."

 

[Honeyman]

Do what she says...Peggie is tops in the business. I believe she'll tell you that some fittings are 1 5/8 instead of 1 1/2 and there was a company (Sealand?) that makes a custom hose adapter w/1 1/2" PVC fittings (341513) that will let you go hard PVC between other fittings.

 

[phantomracer]

oops put the wrong picture there
try this

I figure while I am tearing it apart, I might as well add a valve on the discharge side, so I can dump the tank overboard or to the pumpout. Obviously leaving the valve in the pumpout side 99.98% of the time. I chose a whale valve instead of an on/off, just in case i call for a pumpout and forget to open the valve. So I want all pvc on the discharge side, til above the tank top.

The little jog down in the picture is so I can mount the valve on the ceiling securely, below the tank. Probably use some pvc 45's etc to get the angles right.

My question is I am just curious what the proper way to soft couple pvc.

Using the sealand connectors is better than using home depot stuff?

 

[sailingdog]

Phantom—

Generally, I recommend the head be plumbed directly into the holding tank. This is for two reasons. One, it reduces the complexity of the plumbing. Two, it reduces the amount of hose that can permeate. Three, anywhere you might want to dump the head overboard, you could just as easily pump the holding tank overboard... so you really haven't lost any capability IMHO.

Doing so would eliminate a valve, a hose and a "Y" at a minimum.

 

[phantomracer]

Thanks

Still any input to my original question? how do you properly soft couple the PVC segments?

 

[Peggie Hall HeadMistress]

You still have way more "soft couples" than you need...and in the wrong places.

Keep in mind that every connection is a potential leak or outright failure...so you want to have the fewest possible in a system.

Send me an email if you'd like to talk about it.

 

[catsailor]

I've seen too many soft couples pull apart...

... particularly if you mean common no-hub connectors from Home Depot. Not in moving environment. They fail all the time in an industrial setting. The difficulty is that PVC is smooth and has no barbs.

 

[Steve Dion]

Sealand stuff
http://www.sealandservices.com/hose_fittings.htm

 

[phantomracer]

OK, so I am not supposed to use rigid PVC because it can fail in a marine environment, softcouples can fail. What can I use? I don't want blackwater to stand in the hose..

The reason I wanted to softcouple was I was told not to use all rigid PVC. Plus if I ever need to service it, it will come apart. Have used purpose made couples in pvc systems in my home, and have held for years (even decades). I figure using the sanitation hose instead of rubber, would be more odor free.

Are the sealand products better..are they barbed?

 

[Peggie Hall HeadMistress]

The simple solution:

Use all hose...Trident 101 or 102 Trident Marine: Sanitation Hose which has been on the market for 15 years without a single reported odor permeation failure. Rinse your head discharge hose with fresh water before the boat will sit...and either put the tank discharge fitting on the top of the tank, with a pickup tube inside the tank, or connect just enough hard pvc to reach the top of the tank directly to a 90 degree fitting threaded into a discharge fitting at the bottom of the tank.

There's a bit more that I would do differently than you indicate in your drawing, but you don't seem very interested in discussing how to do it better so I'll quit trying to help you.

 

[phantomracer]

Don't get me wrong, always interested in doing it better...I don't have any system cast in stone.. The point of the thread was how to make proper connections, as I might have sections of rigid pvc and hose in the same system. I am not sure what system I will go in the end. I like my design above...seems logical and flexible..to me anyway. When I am ready to build the system, I will start another thread. I have gone through several iterations of system design, but don't have a final setup yet.

I like the idea of my drawing, being able to discharge the head directly to sea, or to the tank. Also being able to dump the tank to sea or to use the pump out. If I have the pickup inside the tank, I don't see how i can discharge to sea (I actually can not imagine needing it, but like the safety net it can provide)

At this point, I just want to gather the tools I need (best parts and best practices).

But in a hypothetical system I previously posted, I still don't know how to properly connect pvc to hose (ie soft couple, glue, etc). I don't like the idea of too much hard connected pipe that can fail due to vibration and the marine environment. OTOH, using soft coupling can lead to leaks and failures.

I have already purchased about 15' of Trident hose already and couple dozen AWAB clamps

Maybe my original question was a bit simplistic, but all I want to know, at this point, is how to connect rigid pvc and hose without a failure.

 

[sailingdog]

Softcouples work in a house, since the house doesn't move. They're not quite so successful on a boat, due to the vibration and movement.

If the pumpout line is the issue, why not have put a PVC pipe as a riser from the pumpout fitting on the tank with a anti-siphon device at the top that is just above the top of the tank. Then the hose can come down from there an go to the diverter valve. You can use hose for the everything after the riser, since waste will generally not sit in any of the hoses, since the anti-siphon device will prevent it from happening. The suction of a good diaphragm pump or a pumpout boat/dock is more than able to deal with the very small air leak caused by the anti-siphon device on the pumpout line, and should fully evacuate the lines.

I see Peggie beat me to it.

OK, so I am not supposed to use rigid PVC because it can fail in a marine environment, softcouples can fail. What can I use? I don't want blackwater to stand in the hose..

The reason I wanted to softcouple was I was told not to use all rigid PVC. Plus if I ever need to service it, it will come apart. Have used purpose made couples in pvc systems in my home, and have held for years (even decades). I figure using the sanitation hose instead of rubber, would be more odor free.

Are the sealand products better..are they barbed?

 

[phantomracer]

I got the idea of soft coupling from peggy from a post on cruising world (quoted from another site)..which is why I was going to use it. I am going to be connecting the tank to either a valve or pipe section at some point. joining plastic to plastic. I didn't come up with the concept on my own.

It's never a good idea to connect hard pipe (or any other rigid device) directly to any other rigid objective -- the toilet, the tank, pump, or through hull. Boats are subject to quite a bit of shock in heavy seas ... or just banging the dock (it happens to the best of us!) -- enough shock to move things ... a little or a lot, depending upon how well-secured they are. When that happens, if it puts enough stress on the connection, the weakest part will crack ... in most cases, it's the PVC pipe ... but a female plastic holding tank fitting is equally at risk. In cold weather, the risk is even greater, 'cuz the colder it gets, the more brittle PVC becomes . Always "soft couple" hard pipe to anything else with enough hose to act as a shock absorber ... to let whatever is gonna shift, shift without putting stress on the connection.

 

[Head Master18695]

Soft coupling is fine, from rigid pipe to rigid pipe, using the black FERNCO couplings that you find at Home Depot, etc. That's for situations where you have extended runs of rigid PVC or ABS pipe, so that they don't crack from vibration while the boat is running, especially in power boat applications. But you can't soft-couple pipe directly to hose. The clamp won't hold securely on the hose. The simplest way that I know of, of doing that, would be to get a barbed hose joiner fitting. Stuff one end of it into the hose and clamp it. Then put the soft coupler over the barbed end of that, and clamp it in place. You need something that is rigid to clamp onto.