What type of valve is needed?

Good morning,

I need to ad a valve to the bottom of each of our boats fuel tanks to drain off the crud (water) - luckily there is a fitting in each, right at the bottom where the valve can screw in. They have a screw plug in them at the moment - getting that out and screwing the new valve in will be messy but doable.

My question is two fold - I have limited clearance so a gate valve would be ideal however with diesel, is a gate valve ok, or should it be a ball valve (if a ball valve - is there a specific one for diesel?)

And secondly - stainless or bronze - it will be screwing into a steel tank.

Cheers

If clearance is an issue you might try a stainless 90 degree Street Elbow then a nipple of adequate length to bring the drain line out to where it is easily accessible. I would use a ball valve but a gate should work just as well. Be sure to plug end downstream of valve just in case.

Ball valve, stainless or brass.

Gate valves are dandy for many uses. They're not so good when they're in the middle of a length of pipe since you cannot tell by looking at 'em whether they're open, closed or somewhere between (unless you have the indicator type). Because of that, they're not USCG-approved for some uses on a boat; don't know about fuel.

Buy ball valves rated for diesel fuel. Stainless or bronze and you may not have much of a choice; some are stainless with bronze balls. I think CB11 erred to say brass. You won't have much water in the tank but who needs to fret about corrosion and dezincification?

DHeckrotte said:

Buy ball valves rated for diesel fuel. Stainless or bronze and you may not have much of a choice; some are stainless with bronze balls. I think CB11 erred to say brass. You won't have much water in the tank but who needs to fret about corrosion and dezincification?

Click to expand...

I did not err.

IMO, brass would be just fine. And in fact I'd be willing to bet it's the type you find used in most fuel line systems as they come straight from the boat builder.

But if someone feels the need to source and use bronze, go for it.

George
I plan to do the same as you outline.
One trick I have heard about but not used yet is to tape over / plug all tank vents and have a helper pull a vacuum at the fill fitting w/ a wet dry vac.
With a shallow pan under the fitting and some absorbent pads mess should be minimal if you act quickly.
I plan to use a ball valve

Here's one, there are others.

http://www.starmarinedepot.com/moeller-brass-shut-off-valve/pzz5382.html

Bacchus said:

have a helper pull a vacuum at the fill fitting w/ a wet dry vac

Click to expand...

What could possibly go wrong?

1: DO NOT EVEN THINK ABOUT THIS IF YOU HAVE GASOLINE IN YOUR TANK....

2: Even diesel it could be "interesting"....... the ONLY way I would consider doing this is by having a piece of clear hose attached to the fill fitting so I could see any fuel coming out and then switch of the igniter. (Vacuum cleaner.....)

This is a pet thing of mine as I believe in curing the symptom, not the disease.
Your doing a grand job and if you check it regularly you'll never get 'diesel bug' and save yourself a fortune on unnecessary expensive fancy filtration systems..
As long as you have reasonable access, have everything ready, fittings, rags, tools.
From my own experience a ball valve is perfect because you can check it with a glance , mild steel/brass or s/steel are all fine, there's no need to go for bronze.
Make sure the threads on your new ball valve have plenty of PTFE tape on before you start.
Stay calm, loosen the bung slowly until it's just on the last few threads and weeping slightly, then do a warp speed change over to fit your new valve, you'll find it's very easy and you'll lose very little fuel.
Clean up any spills with rags and wash down the area with lemon scented washing up liquid to both clean, and kill any smell.
Put a good squirt of the washing up liquid into the bilges, as it sloshes around it will break down any oil or fuel residues and sweeten your bilges.
Once the valve is a snug fit and everywhere is clean, work out the best place to be able to place a glass jar/receptacle when you wish to check for water/crud and then plumb it for your own convenience.
Use the original bung to close off the end until you need to do your periodic check for water/crud.
p.s If you get a little strip of metal round bar welded/brazed across the end of the bung to make a 'T' piece, you won't need any tools when you go to check your fuel.
I check mine as part of my maintenance routine every month even over winter and have never had 'diesel bug' in over 40 years cruising.

Bacchus said:

George
I plan to do the same as you outline.
One trick I have heard about but not used yet is to tape over / plug all tank vents and have a helper pull a vacuum at the fill fitting w/ a wet dry vac.
With a shallow pan under the fitting and some absorbent pads mess should be minimal if you act quickly.
I plan to use a ball valve

Click to expand...

I used this method to replace a valve in a 275 gallon (100ish gal. at the time) home heating oil tank. Did not spill a drop.

Rob

oscar said:

What could possibly go wrong?

1: DO NOT EVEN THINK ABOUT THIS IF YOU HAVE GASOLINE IN YOUR TANK....

2: Even diesel it could be "interesting"....... the ONLY way I would consider doing this is by having a piece of clear hose attached to the fill fitting so I could see any fuel coming out and then switch of the igniter. (Vacuum cleaner.....)

Click to expand...

Got the vac trick from a plumber. Would not worry with diesel.

Rob

oscar said:

What could possibly go wrong?

1: DO NOT EVEN THINK ABOUT THIS IF YOU HAVE GASOLINE IN YOUR TANK)

Click to expand...

AGREE...Forgot
to add the diesel only caveat

George, can you have someone video the lightning speed changeover, and post it.
My mechanic drained the bottom of my tanks by unscrewing the plug, and he made no mess doing it.
Will you need to remove the plug to check thread and size first, or is there a way around that?

BruceK said:

George, can you have someone video the lightning speed changeover, and post it.
My mechanic drained the bottom of my tanks by unscrewing the plug, and he made no mess doing it.
Will you need to remove the plug to check thread and size first, or is there a way around that?

Click to expand...

Bruce,

I`ll try with the video but it will in all likelihood be so fast that it will be unlikely to be caught on video

Re the thread size, I estimate half inch (5/8 too big, 1/4 too small - bit like the three bears) - I`ll take a chance on the thread (unless someone knows what it is?) if it doesn`t match the plug when I get it out - I have a large wooden plug to jam in there to allow me to exchange it

ulysses said:

If clearance is an issue you might try a stainless 90 degree Street Elbow then a nipple of adequate length to bring the drain line out to where it is easily accessible. I would use a ball valve but a gate should work just as well. Be sure to plug end downstream of valve just in case.

Click to expand...

The solid plug in the end of the drain is a really big deal! I purchased a ball valve drain for the filter bowl on my Racor, and the CG requirements call for a fire resistive bowl (or shield) and an end plug for the drain.

AKDoug said:

The solid plug in the end of the drain is a really big deal! I purchased a ball valve drain for the filter bowl on my Racor, and the CG requirements call for a fire resistive bowl (or shield) and an end plug for the drain.

Click to expand...

Thanks AK - -for me to get into CG controlled territory would take me a bit longer than a long weekend cruise but you never know - sure blow the cobwebs out of the Lehmans

When the ball valve is all installed, make sure you have a way to lock the valve shut. For example a tie wrap thru the handle and secured somewhere to keep the handle from opening.

BruceK said:

Will you need to remove the plug to check thread and size first . . . ?

Click to expand...

Probably not. If you have calipers and a set of thread gauges (Sears?). There is often enough thread visible on the existing plug/nipple to allow measurement. Very reassuring.

The street elbow idea is a good one if vertical clearance is limited. Put a screwed cap on the downstream end of the elbow and install that first, then do the valve. Baby steps make aligning threads easier.

Nobody mentioned sealant. In the rush to get this new valve in place, do not neglect putting diesel-appropriate sealant on the fittings. Without it, you will surely get some slight weeping at any of the new connections including at the tank and the valve, and need to do it all over again!!

only nitrile seals !

bil56 said:

only nitrile seals !

Click to expand...

Or Viton.

If in doubt, soak the seal in a little diesel fuel overnight.
If the seal swells do not use.
If it keeps it's original size it is ok to use.

I was not referring to seals (are you referring to valve components?). I assume these fittings are threaded and should be installed with Permatex #2 or similar on the threads of all components. Also, if multiple components are going into the new assembly, it also helps to tighten all couplings fully before doing the final insertion into the tank threaded port. Lastly, any drain valve like this must be closed with a threaded plug when not in use, and even wired closed.

Thanks to everyone who has thrown their 20 cents worth in - really helpful - esp re thread sealer - will the white plumbers tape do the job with diesel or should I use something like Stag.

I will now back the plug out enough to check the thread, use a gate valve (because of the space) with an elbow on the discharge side with a hose tail. when I have finished draining I shall remove the elbow/hosetail and insert a threaded plug. Valve in Stainless or brass

It is generally recommended to not use plumber's tape (teflon) or even the diesel yellow stuff for fuel related plumbing. Preferably only use a thread sealant such as Permatex that is specifically rated for diesel.

I'll plug for the ball valves. There are some that have mini handles that are very good valves. I've often used those for tight areas. Consider handle removal for installation and then re install the handle after the valve is in place, done that too. Even shorten the handle might help.

I still have two gates aboard my boat and I hate them. I would either have to cut them off or jack up the water tanks to remove them or they would be gone.

If you are installing a brass valve into an aluminum tank then use a steel or SS fitting. I have no quarrel with brass directly into aluminum except if they are in contact with water which is your application as a drain. Use an isolator fitting.

Permatex 2 or Rectorseal 5 both will work with diesel.

My ball valve seacocks have lock collars. Check page 67 of the Whitworths "Cattledog". You might have to remove the handle to screw the valve in, and refit it

BruceK said:

My ball valve seacocks have lock collars. Check page 67 of the Whitworths "Cattledog". You might have to remove the handle to screw the valve in, and refit it

Click to expand...

I tried but got a warning " this site may be hacked" so backed out.

C lectric said:

I tried but got a warning " this site may be hacked" so backed out.

Click to expand...

Worrying. I just tried it, no warnings, info says it was a secure site. I run an internet security package.
Whitworths is a 16 store Australia wide chandlery,I guess it might have credit card numbers from purchases somewhere. To check, I phoned my friend, the Manager of Drummoyne branch in Sydney, he is unaware of any threat, says it`s a secure site. I suggested he call head office anyway.

If a ball valve won't fit, maybe a 90deg "street elbow" will get you aimed the right way and get you clearance. A ball valve is better as the straight shot through means it is less likely to get clogged. Brass is fine for fuel. And cap or plug outlet so it cannot inadvertently be opened and drain the tank.