Fuel Fill Hose Question (PVC?)

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Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
I'm sure this has been asked and answered before... but I couldn't find what I needed using the search function. Apologies in advance for any repeat...

I've been having trouble fouling the carburetor on my outboard... so last night I removed my internal tank and gave it a very thorough cleaning.

Since it was out... I figured it was a good time to assess the merits of its former location in my boat. I want to reposition it (just a little) so that it will occupy space that is less desirable for storage. At present it resides just inside the largest of my cockpit lockers. So essentially it is a fuel locker only. Premium space is being wasted and on a small boat... :naughty:

But there is room under the cockpit sole so.... that seems like a better place and it will also balance out the weight a bit.

By moving the tank I'll need to run a longer fuel fill hose. I don't want to relocate my deck plate (seems like unnecessary fiberglass/gel coat work).

My question! Can part of the new fuel run be solid pipe? I'm thinking schedule 80 PVC would be nice and sturdy but I don't know if PVC and gasoline are compatible over the long term. I found a chemical compatibility chart from a company called "Spill Tech" that lists PVC/Gasoline compatibility as "Moderate" (good was the best rating available). What does moderate mean? They also had a rating of "not recommended". Since PVC was not given a "not recommended" rating.. can I infer that "Moderate" implies that it is recommendable? (Two negatives makes a positive kind of thing) The highest possible rating was "Good". So I found this data to be less than informative.

Moeller has a recommendation sheet that says not to use rigid fuel lines. My understanding is that things move on boats and you want the flexibility so the line does not get stressed and crack. So I'm thinking that if I use flexible pipe on the ends on my PVC pipe... I'll still provide the needed "flexibility" and prevent any stress on the PVC.

I know some of you will say... why not just buy the flexible pipe. I'm not opposed but it is really not all that flexible and a 90-deg turn is out of the question with this stuff. So directing the fill pipe so that it does not interfere with premium storage space will be difficult. And the stuff is expensive. I found a place selling the flexible hose for $6/ft and for the run I need it will cost me about $50. But I already have 3' of flexible hose. And a piece of PVC pipe and fittings will run me $10. So... I'll save $40 and the PVC pipe will allow me to direct the run more precisely into those "unusable" spaces under the cockpit.

I drew a cartoon what what I'm thinking I'd like to do.

If you know of any reasons why this is a bad idea, please share... working with gasoline in closed spaces ... I really don't want to overlook anything.

Thanks,

r
 

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Mar 6, 2008
1,243
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
1) rigid pipes are not suitable to be used on boats as it is going to break as the boat's fiberglass hull is flexible.
2) PVC and fuel - specially gasoline - are a bad combinations as gasoline will dissolve the PVC.
Buy 3/8" gasoline hose from any auto supply and be confident that it will not cause any problem.
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
i would bit the bullet and use fuel fill hose rated for the purpose.....i just cant see putting my boat in harms way over 40 or fifty dollars or my life for that matter.....are you going to vent the tank as well......

regards

woody
 
Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
1) rigid pipes are not suitable to be used on boats as it is going to break as the boat's fiberglass hull is flexible.
2) PVC and fuel - specially gasoline - are a bad combinations as gasoline will dissolve the PVC.
Buy 3/8" gasoline hose from any auto supply and be confident that it will not cause any problem.
Thanks for the input.... maybe what I need is some sort of elbow that is rated for fuel and affix the flexible hose to that.

I do know for certain that gasoline will not dissolve PVC. It will dissolve styrene so that may be what you are thinking about. I'm more worried about prolong exposure leading to the PVC becoming brittle by leaching out the phthalic esters that keep the plastic "soft". I could not find any data pages that said anything about that but I'd like some definitive data before I put it on my boat. I found a guy who claims to have soaked a piece of schedule 40 in gas for four months with no ill effects... but 4 months is not that long IMHO.
 
Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
i would bit the bullet and use fuel fill hose rated for the purpose.....i just cant see putting my boat in harms way over 40 or fifty dollars or my life for that matter.....are you going to vent the tank as well......

regards

woody

the vent line is already in place. The issue is more about making good use of the locker space and not so much $40. If anyone knows of a safe way to make a 90-deg elbow that I can affix the flexible hose... that might be a better way to go.
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
get the correct size brass 90 degree threaded pipe elbow and a couple of brass nipples and make you own 90 and double hose clamp the hose on to the new 90 that should work just fine...on the old wooden Chris crafts they use a brass fill pipe

regards

woody
 
Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
get the correct size brass 90 degree threaded pipe elbow and a couple of brass nipples and make you own 90 and double hose clamp the hose on to the new 90 that should work just fine...on the old wooden Chris crafts they use a brass fill pipe

regards

woody

Brass! Right! Duh:doh:

Thanks Woodster. That is what I'm going to do. I should be able to run the hose exactly as needed.

I knew there were smarter than I people on this list... ;)
 

KD3PC

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Sep 25, 2008
1,069
boatless rainbow Callao, VA
Brass! Right! Duh:doh:

Thanks Woodster. That is what I'm going to do. I should be able to run the hose exactly as needed.

I knew there were smarter than I people on this list... ;)
copper will work just fine as well as the brass

Be safe and pony up the $$ for the correct fuel line, approved by the USCG for your fuel use. Double clamps. Auto stuff is not rated for concealed marine use.

Gasoline leaks in the cabin are not good for long term use of the boat
 
Jan 22, 2008
880
Fed up w/ personal attacks I'm done with SBO
The USCG is specific about the installation of below decks fuel systems and has a complete section on gasoline alone. Any reason not to do it their way? What will your insurance company have to say about a non-compliant fuel system? This is not a good area for innovation or restrictive budget.

Also, don't forget that most gasoline is blended with alcohol (ethanol) that brings a whole new bag of surprises. ANY fuel hose handling gasoline must be alcohol rated these days. Don't omit the fill plate ground wire (#10) or double clamping.
 
Oct 5, 2010
322
Catalina 30 mkII St. Augustine
When you or your loved on is lying in the burn unit you would give all you have to go back and spend the few extra dollars to do the job right.
 
Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
Thanks everyone.... and just for the record... working with auto fuel line was not my suggestion. I wanted a way to put a 90 deg turn in the fuel line so I could route the line without cutting my locker space in half with the existing line (see original post). I think Woodsters suggestion will do the trick for me. I went to Lowes tonight and priced out the parts I'll need ... $37 for each turn and I'll need two .... maybe three. So no savings... but I'll get to route the fuel line through a previously unusable space and make way for a very nice locker space in the cockpit. It is a really deep locker so I'm thinking a few storage tubs will fit nicely in there.... or maybe I'll move the ice box into that space and clear out some room in the galley for something more useful.:)
 
Jan 22, 2008
1,660
Hunter 34 Alameda CA
How difficult would it be to move the deck fill plate closer to the tank (like right above it)?

My handbook of thermoplastics and elastomers only gives a good rating at best for Type I PVC at room temp and less at 150F. Type II PVC is worse. Don't know what hardware store PVC is but anything less than excellent isn't good enough. The leaching is a factor as well. The consensus here is to avoid it.

Allan
 
Mar 26, 2011
3,626
Corsair F-24 MK I Deale, MD
Having many years on the refinery business as a chemical engineer, the following is based upon working with actual installations of PVC on petroleum liquid and vapor applications:

Do NOT use PVC with gasoline. There are many reasons:
* It will soften with some blends and crack with others; This may take time, but it is not dependable. It will always weaken.
* The joint glue will quickly fail, perhaps in a week.
* PVC builds static during pumping and has been associated with tank explosions; I did the accident investigation on one such near-fatal incident.
* Permiates badly. Unlike sewage where PVC does well, it will reak of gas.

It will do better with diesel, but still will not perform to an "A" rating. Don't.

The only advantage of PVC is that it is cheap and available. That is not enough and there is nothing to recomend it for fuel lines, even for one fitting. Don't.
 
Jan 22, 2008
1,660
Hunter 34 Alameda CA
Having many years on the refinery business as a chemical engineer, the following is based upon working with actual installations of PVC on petroleum liquid and vapor applications:

Do NOT use PVC with gasoline. There are many reasons:
* It will soften with some blends and crack with others; This may take time, but it is not dependable. It will always weaken.
* The joint glue will quickly fail, perhaps in a week.
* PVC builds static during pumping and has been associated with tank explosions; I did the accident investigation on one such near-fatal incident.
* Permiates badly. Unlike sewage where PVC does well, it will reak of gas.

It will do better with diesel, but still will not perform to an "A" rating. Don't.

The only advantage of PVC is that it is cheap and available. That is not enough and there is nothing to recomend it for fuel lines, even for one fitting. Don't.

Well RGranger, remember when we were in college studying Chemistry and they told us Chemists don't know anything about Engineering and Engineers don't know anything about Chemistry, and Chemical Engineers don't know anything about either one?;);) Ahh those classic good natured rivalries. Well after 40 years, I don't believe that's true now. Better listen to Thinwater. Leave the PVC for the head.

With all that being said, how about exhaust pipe fittings? You could buy a thin wall elbow at Kragen's and have a sheet metal shop roll a bead on it that would allow you to clamp into the flexible stuff.
 
Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
Thanks Allan

About half way up this thread... I mentioned that I was going to use brass elbows and go with approved fuel hose.... but nobody (and I'm guilty of this too) reads an entire thread when it is long and just chimes in at the end. So I'm getting a lot of the same advice from many sources ... But I do appreciate it ;)

It would be nice if there was a way to close a thread once you get a problem resolved.
 
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