Suitable plastic for sight guage?

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PetiteFleur

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On a friends boat at the weekend, went to check the sight guage on the diesel fuel tank and impossible to make out the level as the plastic had discoloured to a reddish brown colour! The tank is coming out this winter so would be a ideal time to replace the plastic tube - what is the best type to use? Currently it is of the clear pvc braided type.
 
PetiteFleur said:
On a friends boat at the weekend, went to check the sight guage on the diesel fuel tank and impossible to make out the level as the plastic had discoloured to a reddish brown colour! The tank is coming out this winter so would be a ideal time to replace the plastic tube - what is the best type to use? Currently it is of the clear pvc braided type.
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That's what mine is, not too bad to see as my pipe is in good order. I have considered putting something that floats in diesel and doesn't dissolve in the pipe to make it easier, just not got around to researching the best material.
 
At our club we have Fire and safety Inspections of boats every 3 years. Plastic tube as a sight gauge is a definite nono due to likely failure ina fire with the resultant fire running out. olewill
 
William_H said:
At our club we have Fire and safety Inspections of boats every 3 years. Plastic tube as a sight gauge is a definite nono due to likely failure ina fire with the resultant fire running out. olewill
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The oil tank gauges with a floating pea have a press button valve at the bottom of the column. The plastic tube is only open when the button is being pressed. HSE compliant.
 
PetiteFleur said:
On a friends boat at the weekend, went to check the sight guage on the diesel fuel tank and impossible to make out the level as the plastic had discoloured to a reddish brown colour! The tank is coming out this winter so would be a ideal time to replace the plastic tube - what is the best type to use? Currently it is of the clear pvc braided type.
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I used nylon pipe from Pirtec as thats compatible with copper gas fittings & also have a cock at the bottom to isolate the gauge
 
William_H said:
At our club we have Fire and safety Inspections of boats every 3 years. Plastic tube as a sight gauge is a definite nono due to likely failure ina fire with the resultant fire running out. olewill
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Proper sight glasses are protected by a normally closed valve.
Are you allowed to have plastic fuel tanks in Oz?
 
My boat came with a graduated teak dipstick that one of the previous owners made. Simple but effective.
 
I'm about to do the same job. Our sight gauge has given us 13 years of service and was there when we bought the boat. I've chosen 6 mm. reinforced pv chose plus 4 new Jubilee clips. I've already made a vertical oak spar which sits just behind the hose and offers it protection against accidental impacts from items in the locker. This spar is hooked onto the stubs of pipe and is painted white and marked at 1 gallon intervals. Just need to develop a technique to minimise fuel spillage when doing the changeover.
 
Reeac - I'd really be thinking about a 'normally shut' cock on that pipe - when I used to clean up domestic oil spills for a living, I once attended an incident where the flexible sight hose had developed 'brewer's droop' and sagged down out of the mounting clips. It shouldn't have been a problem except someone had put a clothes peg on the pull-out button of the stop cock, holding it open, and the resultant spill was very ugly!
 
I've certainly considered installing a shut off valve but it would complicate the changeover and, as I've stated, the present tube has always behaved perfectly even with just one small clip at each end. My only concern has always been that it might be hit by other locker contents in rough weather or by someone carelessly slinging a fender or other item in there ...hence the protective oak spar.
 
reeac said:
I've certainly considered installing a shut off valve but it would complicate the changeover and, as I've stated, the present tube has always behaved perfectly even with just one small clip at each end. My only concern has always been that it might be hit by other locker contents in rough weather or by someone carelessly slinging a fender or other item in there ...hence the protective oak spar.
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Adding a cock to the plastic tube was included in my purchase survey.
my tube goes back into the tank at high level so no fear of spillage
 
The sight tubes have to be open to atmosphere to work, but I can't see why there couldn't be a valve on the top of the tube. I noticed your oak spar which sounds a good idea.
 
A plastic sight tube is a potential failure point so is best avoided. Why not fit a proper float operated fuel gauge with a remote readout admittedly they bounce around a bit in the sea but give a good idea of contents and they are fine in Harbour also they're not particularly expensive.
 
Corribee Boy said:
The sight tubes have to be open to atmosphere to work, but I can't see why there couldn't be a valve on the top of the tube. I noticed your oak spar which sounds a good idea.
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If the tube is connected back into the top of the tank, there is no fear of spillage, and no need for a valve at the top. IMHO it would seem irresponsible not to have a valve at the bottom, particularly if it's in a locker, and liable to be hit by gear. (Ideally a normally closed push-button).
I like a sight glass. There are no moving parts, no electrics, and an accurate readout. However, depending on the layout of the boat's tank(s), a sight glass might not be suitable.
 
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