Closing off sight gauges

On another forum, a boater mentioned how he discovered a boat in his marina had a diesel leak that was caused by the clear plastic tubing used for the sight gauge was cracked, leaking fuel all over the bilge. *I never thought about it as previous owner always kept the valves to the sight gauges open 24/7. *Do you all keep your sight gauges open all the time or close them off and only open when you want to actually inspect the fuel level of the tank?

i always kept mine closed

Hiya,
** I can see no advantage of having the valves open all the time.* Takes seconds to check levels and then close valves again.*

I open mine only when I want to check the level - otherwise mine are CLOSED 7/24.
I also keep my main fuel supply lines and engine thru hulls closed when the boat is at the dock. But then my diesel heater has a direct line to the Port tank so it can run with the mains closed.

Looks like everyone keeps them closed! I hate to say it but I had never pondered it til I read about the the sight gauges failing so last time I was up at the boat I shut them!

Woodsong wrote:

Do you all keep your sight gauges open all the time or close them off and only open when you want to actually inspect the fuel level of the tank?

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In my opinion, and in the opinions of everyone I've seen talk or write about this, sight tube valves should always be left closed unless you're actually going to take a reading.* Then open it, take the reading, and close it.

Our boat has sight tubes on all four saddle tanks.* The day tank has a fuel gauge at the helm station.* The sight tubes on our boat have valves at the bottom but no valves at the top.* This is NOT*a good or safe*design.* A proper sight tube installation should have valves at the bottom and top of the tube.

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the valves are*closed except to check the fuel leave and then I close them again.

I keep mine closed except when checking the level. The ones on my Monk are of clear hose which after acouple of years gets stained by the dye in the diesel, they are very easy to replace. Slip the top off of the barb, blow the fuel down and out the bottom back into the tank. Close bottom valve and change out the tube. Didn't spill a drop.
Steve W.

Not only do I keep mine closed unless I'm reading them, a surveyor stated in 2006 that a sign was required, something to the effect that they had to be closed unless reading them. Said it was an ABYC recommendation. So now I have two little plastic signs telling me to keep 'em closed.

Thanks all for the confirmation. Ours are closed now, as of my trip up to the boat last week when I had the granite countertops installed and I'll keep them closed now except for when taking a reading. I just had never thought about it until the other week.

By regulation for survey the valves for sight gauge glasses should be self closing.
So they are instantly opened for reading and close immediatly upon release.
In the photos of my engine room on the engine change out thread you will see the lever operated valves at the bottom of my gauge glasses.

Benn

-- Edited by Tidahapah on Thursday 16th of December 2010 10:38:29 PM

I just wish I had sight gauges!*

Amen, rwidman. My old MT had tanks replaced at some point in its shadowy life, but there's no way to tell how much fuel's in them, other than a MKI Mod 2 dipstick.

I experimented with installing float switches in the top inspection holes, and after fiddling with them to avoid a baffle in the tank, and then find the d-- things just don't work reliably anyway, ., I am back to sticking the tanks, logging gallons in, etc. Finally got a dipstick marked reasonably accurately, *by knowing *how much I was putting in at each fuel stop.

Installing sight gauges would nice, but at this stage in the old boat's life (and mine!) it's probably not gonna happen. *





-- Edited by ARoss on Monday 20th of December 2010 06:01:57 PM

Installing sight gauges would nice, but at this stage in the old boat's life (and mine!) it's probably not gonna happen.



Site gauges are fine for an educated guess .

Flo Scan if you want to really know.

FF wrote:





Site gauges are fine for an educated guess .

Flo Scan if you want to really know.

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Um, you really can't get a more reliable read than a sight gauge! *Acting as a water level it tells you in no uncertain terms the level of fuel sitting in your tanks? *It doesn't get more accurate than that????

Woodsong wrote:
"Um, you really can't get a more reliable read than a sight gauge!... * it tells you in no uncertain terms the level of fuel sitting in your tanks."

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That's right! (Assuming you've opened the valves to let the fuel seek its level.)

*


-- Edited by SeaHorse II on Tuesday 21st of December 2010 10:57:46 AM

In fact, I would assume that the best way to calibrate your Floscans would be to use a sight gauge!!!

Mmm. The Chinese fellers who built our boat seem to have overlooked putting valves on the sight gauges, although they are inside protective shrouds. When I asked him about this, our surveyor said they were not "required". Seems to me though like a good idea to have them. Oh well, another project. Just have to figure out how to do it without removing 125 gallons of fuel from each tank. Any ideas on how to do this?

I believe--- but I am not positive--- that valves on sight gauges are a requirement in the ABYC design standards. The reason is obvious--- if a sight tube should break, crack, or otherwise develop a leak, all the fuel in the tank down to the level of the leak will end up in the bilge if there are no valves. Unless someone is there to stop it, the bilge pump will then pump most of this fuel overboard.

The right way to do it is to have valves at the top and bottom of a sight gauge. When closed this completely isolates the tube so if it cracks or breaks, the only amount that will leak into the bilge is the fuel in the tube.

Our boat's tanks have sight gauges that are valved at the bottoms only. While this is better than nothing, it's not a proper setup. The reason is that when the tanks are full, there are a fair number of gallons of fuel in the tank above the upper sight tube connection, even though the upper connection is as close to the top of the tank as it was practical to make it. So even with the valve closing off the bottom of the tube, should a leak develop the fuel at the very top of the tank will leak out until it's dropped to the level of the upper sight tube connection. Once the fuel in the tank has been drawn down below the level of the upper sight tube connection this is no longer an issue.

I suppose one could get real fancy and connect the upper end of the sight tube via a couple of 90-degree fittings into the actual top of the tank so that even when full the upper sight gauge connection will be above the level of the fuel.

Marin wrote:I believe--- but I am not positive--- that valves on sight gauges are a requirement in the ABYC design standards.

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You belief is founded on fact. ABYC H33.5.8 states that if a sight gauge is used it must have a valve at the top and bottom.

It also calls for a placard adjacent to the gauge that reads: WARNING Leaking fuel is a fire hazard. Avoid serious injury or death from fire. Keep both sight gauge vlaves closed except when checking fuel level.

The reason for the upper valve is so that the opening will not become a blowtorch in the event of an engine room fire that boils the tank contents.

But, and this is the bottom line, ABYC writes "standards" not rules. unless the ABYC standard is incorporated by reference in the Code of Federal Regulations, they are voluntary only. There are no penalties (other than the normal risk of death from jury rigged construction and repairs) for not following ABYC recommendations.

46 CFR**182.440**states: "Tubular gauge glasses, if fitted to diesel fuel tanks, must be of heat resistant materials,adequately protected from mechanical damage, and provided at the tank connections with devices that will automatically close in the event of rupture of the gauge or gauge lines."

The big but regarding that reg is that it applies to T-boats, small passenger vessels <100 tons/12 pax or fewer.

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"In fact, I would assume that the best way to calibrate your Floscans would be to use a sight gauge!!!"

Far too coarse,

The way a Flo Scan is calibrated is with repeated fuel fills . This can get the unit within 1 or 2%.

Look at your "half" line on the site gauge , can you tell me it is 96 gal or 106gal on a 200G tank?

ARoss wrote:

Amen, rwidman. My old MT had tanks replaced at some point in its shadowy life, but there's no way to tell how much fuel's in them, other than a MKI Mod 2 dipstick.

I experimented with installing float switches in the top inspection holes, and after fiddling with them to avoid a baffle in the tank, and then find the d-- things just don't work reliably anyway, ., I am back to sticking the tanks, logging gallons in, etc. Finally got a dipstick marked reasonably accurately, *by knowing *how much I was putting in at each fuel stop.

Installing sight gauges would nice, but at this stage in the old boat's life (and mine!) it's probably not gonna happen. *
-- Edited by ARoss on Monday 20th of December 2010 06:01:57 PM

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I can't "stick" mine either.* I thought I might be able to through the deck fill but there's a "S" bend in the hoses.* Electric gauges are not that accurate.* The only way to know when the tank is full is to fill it until fuel comes out the vent and that's frowned upon in most places.* As for when it's empty, I don't really want to find out.

As for a flo scan, well they are pretty expensive for a diesel.* And since I have two tanks and one engine, I could still run one tank dry and suck air.

*


-- Edited by rwidman on Wednesday 22nd of December 2010 08:04:24 AM

FF wrote:

"In fact, I would assume that the best way to calibrate your Floscans would be to use a sight gauge!!!"

Far too coarse,

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Floscans are great, had them on my last boat and loved them, but they are darn expensive, and take time to install.* Now, my sight gauges are calibrated quite accurately.* I started with an empty tank, and simply marked the gauge at 50 gallon increments.* If the boat is level, I can easly get an accurate measurement of the fuel remaining.* To determine actual fuel consumption, I simply top off the tanks to the exact same place on the site gauge and do the math.* Certainly my method won't allow for instant feedback like the Floscans, so it's harder to find the "sweet spot" for fuel consumption, but it's close enough for us.....................Arctic Traveller

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Reviving this old thread.

I am getting paranoid about not having valves on my sight tubes, which are plastic hose slipped over welded in elbow fittings located top and botton on the tanks and secured to the fittings by hose clamps.

Its going to be a frig to figure out how to put valves on these. It will probably involve draining the tanks and having someone (not me) cut out the fittings and weld in new fittings that are tapped for threads. Unless I can use something like SharkBite fittings if they can be used with diesel fuel.

Also having trouble finding self closing valves. McMaster Carr has some but they are part of/or applicable to a glass sight tube assembly and are quite pricey.

I would really like to use the push button type of self closing valve (I think that Walt may have this type on Seahorse II) but so far I have not been able to locate a supply source for these in the USA. They seem to be available in Australia and England. Does anyone know of a US source for these? Like the one shown here but with NPT threads.

Anyone have any bright ideas?


-- Edited by dwhatty on Wednesday 24th of August 2011 11:37:38 AM