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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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jointing oil fittings
What's pukka for jointing fittings (compression and straight threads)
for heating oil? I heard that PTFE tape was not OK. My Purimachos green stuff says it's OK for oil but I wonder if it'd be that effective - I don't think it gets thick and sticky over time like the white stuff. Also: it's a gravity feed system and it'd be easier to arrange the pipework with a rise & fall to accomodate the filter and a butterfly valve, as below: ________ | | | tank | |________|--- ___________ | ___?_ | | | | | | | -------------------------- ---| appliance | |___________| Should I have an air bleed at a high point in the pipework? (the point marked ?) Or should I try not to have a fall at all (do-able, but awkward). tia Stan the Span |
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jointing oil fittings
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#3
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jointing oil fittings
Grunff wrote in message ...
Stanley Spanner wrote: What's pukka for jointing fittings (compression and straight threads) for heating oil? I heard that PTFE tape was not OK. My Purimachos green stuff says it's OK for oil but I wonder if it'd be that effective - I don't think it gets thick and sticky over time like the white stuff. Compression fittings (all of them, oil, air, water) are exactly that - they work by compressing metal against metal. The olive is the thing that makes the seal. There is no need for *any* goop or tape. In theory :-) I usually put some green stuff on even new joints, and always on old ones - belt & braces. If you make a compression fitting and it leaks, it's because either you didn't make it right, or you haven't tightened it enough. - or there's [been] a bit of grit in the joint, which has scored the metal surfaces so they don't seal perfectly. (That's with those of us who don't plumb in clean-room conditions :-) Huge wrote: If you make a compression fitting and it leaks, it's because either you didn't make it right, or you haven't tightened it enough. .... or too much! Good point, and it's more easily done with 8mm and 10mm fittings. ... and soft-as-butter fully annealed table Y tube grrr All my oil compression fittings were made without any joining compound or tape, and none have leaked. As for tapers, then PTFE tape is absolutely fine. What about parallel threads? (The filters and butterfly valves all have these.) Normally I'd use PTFE: the panel at Plumb Center reckoned that was out for oil; but I've just checked Treloar who says "Petroleum resisting compounds and PTFE tapes which remain slightly plastic make the most satisfactory joints; hemp and hard-setting jointing compounds should be avoided". I assume he means PTFE tapes in general, not 'Petroleum resisting PTFE tapes' as I understand PTFE is pretty inert stuff and I doubt it would be bothered by heating oil. OTOH he also says soft soldered joints are out, which means I've got more &%^* compression joints to make on soft tube :-( cheers Stan the Span |
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jointing oil fittings
Stanley Spanner wrote:
What's pukka for jointing fittings (compression and straight threads) for heating oil? I heard that PTFE tape was not OK. My Purimachos green stuff says it's OK for oil but I wonder if it'd be that effective - I don't think it gets thick and sticky over time like the white stuff. Also: it's a gravity feed system and it'd be easier to arrange the pipework with a rise & fall to accomodate the filter and a butterfly valve, as below: ________ | | | tank | |________|--- ___________ | ___?_ | | | | | | | -------------------------- ---| appliance | |___________| Should I have an air bleed at a high point in the pipework? (the point marked ?) Or should I try not to have a fall at all (do-able, but awkward). tia Stan the Span Compression, but beware that they are weak at the normal pipe diameter. PTFE tape doesn't work well - use Red Loctite to seal. Try to avoid up and under routing - you will just have to bleed it - don't put bleed valves on, just steel yourself and suck the bloody pipe full and then never ever let it run dry again |
#6
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jointing oil fittings
Huge wrote:
(N. Thornton) writes: (Stanley Spanner) wrote in message . com... Also: it's a gravity feed system and it'd be easier to arrange the pipework with a rise & fall to accomodate the filter and a butterfly valve, as below: ________ | | | tank | |________|--- ___________ | ___?_ | | | | | | | -------------------------- ---| appliance | |___________| Should I have an air bleed at a high point in the pipework? (the point marked ?) Or should I try not to have a fall at all (do-able, but awkward). I believe that would be fine as youve drawn it. All that matters to the oil is the relative heights of start and finish, and length of pipe. Sharp bends would add more resistance to flow. As long as your high point is below the top of the oil in the tank there is no problem. Just so long as the rise in the pipe does not go above the level of the oil in the tank, in which case you will have to suck/blow the oil through initially, and you are asking for air-locks. I repeat, common sense is on your side, bitter experience - or rather diesel tasting experience, is on mine. On a long run, any uphill run is a problem, no matter what the final height is. Once full of oil, both my pipes ran freely under gravity, and no point in the pipe was above the final outflow point. BOTH refused to flow with air in the pipes. I do not understand this either. |
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jointing oil fittings
The Natural Philosopher wrote in message ...
Compression, but beware that they are weak at the normal pipe diameter. PTFE tape doesn't work well - use Red Loctite to seal. Try to avoid up and under routing - you will just have to bleed it - don't put bleed valves on, just steel yourself and suck the bloody pipe full and then never ever let it run dry again Plstic bag loosely over end of pipe before sucking would make life less unpleasant - but I can just imagine some incompetent person breathing the bag up and choking. So I'd best say dont. Regards, NT |
#8
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jointing oil fittings
N. Thornton wrote:
The Natural Philosopher wrote in message ... Compression, but beware that they are weak at the normal pipe diameter. PTFE tape doesn't work well - use Red Loctite to seal. Try to avoid up and under routing - you will just have to bleed it - don't put bleed valves on, just steel yourself and suck the bloody pipe full and then never ever let it run dry again Plstic bag loosely over end of pipe before sucking would make life less unpleasant - but I can just imagine some incompetent person breathing the bag up and choking. So I'd best say dont. Well bugger me. Why didn't I think of that. I am sure there are some used condoms as well around somewhere... Regards, NT |
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