Fuel sight tubes

My 88 IG has fuel sight tubes that need to be replaced. I have looked around and everyone tells me to replace them with electronic devises. I still like the tubes, makes me go and check my fuel, oil and cooling levels more often. So my question is were can I look for some new tubes since my old ones have discolored quite a bit. Any help is welcome.

If they are 1/2" to 3/4" glass you may have luck at a plumbing supply house that caters to industrial/manufacturing customers(not residential). Glass sight tubes are common stock items in industrial boiler plants.

Mine has clear fuel tubing that is labeled as diesel safe, but I keep both upper and lower valves closed unless taking a reading just to be sure.

I like the sight tubes as well. They are an absolute measure which provides great confidence. Plus, if you have electronic fuel gauges the sight gauges can confirm that they are correct.

If the fuel gauges are plastic tubing, be sure to get tubing that will not absorb the red dye from the diesel fuel and eventually become unreadable. Try Coastline or US Plastics. Look for Tygon fuel and lubricant tubing which is yellow in color (you can see through it easily). They are only a couple of dollars apiece.

You can put a piece of tape adjacent to the tubing and calibrate it based on the number of gallons in the tank and its depth.

You can also get water plastic tubing from the same sources as well.

Previously discussed here

http://www.trawlerforum.com/forums/s6/diesel-fuel-site-gauge-231.html

Spring loaded ball valves

http://www.mcmaster.com/#spring-return-ball-valves/=j5jduz

Pain going down to open valves , view level then close valves.

The pump gauge system that shows the inches of fuel can handle multiple tanks , multiple tank contents.

Requires a top hole for the down tube.

I like sight tubes best...whether spring loaded or not...they also show the quality of the fuel at a glance.

There are somewhat reliable and accurate gauges out there...just not AS accurate or reliable.

If they are glass I would guess they can be cleaned...if not I just say them some place online...maybe McMaster Carr. If vinyl tubing ....easy peezy...

Only a dipstick can be as accurate as a sight tube on a tank. Traditional gauges are OK, but not very accurate. Electronic fuel monitoring systems can be pretty accurate if callibrated accurately, but the cost is about $1K per engine just for parts.

If I had sight gauges, I would keep them and clean or replace the glass or tubing. If you just need glass tubing without any attached fittings, a company that supplies lab equipment to schools and such would probably have it.

I just replaced our braided PVC sight tubes with non-staining rigid polycarbonate (from McMaster Carr). We have upper/lower shut off valves with compression fittings both ends of the tubes. Inexpensive solution. The polycarbonate is much more durable than glass (unless protected in metal sheath) and should not stain like the old PVC tubing.
One other simple, inexpensive fix was to attach (plastic electrical ties) wooden yard sticks (Home Depot) to the back of each sight tube for easier calibration. Just read the fuel height in inches and relate to calibration chart.
Upper and lower valves are normally closed except for reading.

When our boat was retanked in 1997 the four new saddle tanks were equipped with sight gauges. I have no idea what the tube material is-- it's flexible tubing as opposed to glass--- but in 14 years while some of the tubes have taken on a slight pinkish hue it's still very easy to see the fuel level.

Our tubes have valves on the bottoms only, which is not a good idea. They should have valves at the top and bottom. And it's smart to keep the valves closed except when taking a reading.

I use clear fiber reinforced plastic tubing, the shut off valves are always closed except to take a reading. I have a band of electrical tape at the 1/2 full level which gives me a good estimate of how much will be needed.
They, in my case are very easy to change, remove the top of the tube, blow into it to force the diesel back into the tank and shut off the bottom valve when the tube is completely empty. put an absorbent pad, I use pet "piddle pads", under it and make the change. Personally, I would be worried about glass tubes unless they were well protected. I last changed tubes about 3 years ago and they are lightly stained butthe level is still easily viewed
Steve W

Our tanks have clear, flexible plastic sight tubes attached to unthreaded brass elbows (approx 3/8" OD) with no shut off valves. I want to add valves. Does anyone have any suggestions on how to install valves other than cutting out the elbows and welding/brazing in threaded elbows. i.e. is there some sort of a fitting (like SharBite or ProBite) that could be used. Of course, I guess there is no way around having to drain the tanks to do this. Or is there?

dwhatty said:

Our tanks have clear, flexible plastic sight tubes attached to unthreaded brass elbows (approx 3/8" OD) with no shut off valves. I want to add valves. Does anyone have any suggestions on how to install valves other than cutting out the elbows and welding/brazing in threaded elbows. i.e. is there some sort of a fitting (like SharBite or ProBite) that could be used. Of course, I guess there is no way around having to drain the tanks to do this. Or is there?

Click to expand...

We have used Swagelok fittings with high pressure and various compressed gasses. I don't see why they wouldn't work here. They may not be CG approved but I think it would be an improvement. I think you can also get them in brass.

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Check out Parker Prestolok fittings. Not sure they would satisfy a surveyor but they might fit your application. The sealing material (nitrile rubber) is diesel resistant. If you size them correctly to your existing elbow they might just push on. If you attach the sight tube (rigid polycarbonate tubing) into the Prestolok before you remove the existing lower flexible tubing from the elbow, you might not have too much difficulty (read leakage!!) getting the Prestotok assembly with the prefitted sight tube onto the existing elbow quickly. A finger (and a helper) is always handy for stopping the flow!!! Once you get the bottom fitting attached with the sight tube vertical you can take your time installing and connecting the upper Prestolok. No idea if this will really work but you might want to check it out??

Don't be tempted to get overcomplicated. Sight tubes are are really no big deal and if you calibrate them carefully...they are probably the most accurate measuring device on the boat with the exception of WGPS...you just have to be smart enough how to make sure....

I don't see why sight tubes are any big risk. If you are worried about a leak, compared to some fuel plumbing systems described here, between fuel polishers and manifolds, they have more connections than the New York City Water department...

Sight gauges are tried and true in the commercial world...with proper maintenance and you ARE looking at them regularly if using them, they should be the least of your worries.

I put this on 5 years ago after the normal plastic tubing became too stained to read (after 4 years). The tubes are as clear now as they were the day I put them on - this stuff works for diesel:
http://www.mcmaster.com/#catalog/118/123/=j68ifh

It's the Tygon tubing that someone else mentioned - this is a reference for exactly where you can get the right stuff.

A/C,

Did you just go with the Ultra for the little cost difference?

psneeld said:

Don't be tempted to get overcomplicated. Sight tubes are are really no big deal and if you calibrate them carefully...they are probably the most accurate measuring device on the boat with the exception of WGPS...you just have to be smart enough how to make sure....

I don't see why sight tubes are any big risk. If you are worried about a leak, compared to some fuel plumbing systems described here, between fuel polishers and manifolds, they have more connections than the New York City Water department...

Sight gauges are tried and true in the commercial world...with proper maintenance and you ARE looking at them regularly if using them, they should be the least of your worries.

Click to expand...

I aggree, but the site tubes should have shut off valves top and bottom.

JD said:

A/C,

Did you just go with the Ultra for the little cost difference?

Click to expand...

I should have given the part number of the actual stuff I bought - 5046K15.

I'm a sucker for the word "ultra".

Isolation valves are a good idea, although the biggest risk to a broken sight tube is ensuring everything below is solidly attached and clear of junk. There should be no chance of objects such as tool boxes, cray pots, or the tanks themselves moving and causing damage.

If any of you guys want top quality level measurement, there is a variety of industrial components available such as this.
Kenco Engineering - MECHANICAL LEVEL MEASUREMENT

Reminds me of the story I read on this website (I think??) some time ago about the guy who kept his engine room warm in winter with regular filament light bulbs. One day he backed into one of them, broke it and electrocuted himself!! Nobody wants a few (hundred?) gallons of diesel in the bilge - especially the USCG, EPA etc. Use the right materials and close the valves top and bottom. The risk of doing less could be very very costly!!

few (hundred?) gallons of diesel in the bilge - especially the USCG, EPA etc.

This is just the question someone with a CAV Euro style filter with a glass section should ask themselves.

The glass can be overtightened , and may not brake for months, then SURPRISE!