NONE CONBUSTABLE OIL UNDER PRESSUE IE DIESELING.

Discussion in 'Piston & Spring' started by RAIDER, Jan 15, 2018.

  1. RAIDER

    RAIDER Active Member

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    Trying to find a light oil that will NOT diesel in spring air rifles. Last thing I want is mucking up seals and piston heads. I think years ago I used sewing machine oils but searching google I can’t get the info on combustability. Any info you have that could point me in the correct direction.
    Jeremy
     
  2. Amac

    Amac Active Member

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    I use Abbey SM 50 which is a none dieseling product. Works for me!
    Andy
     
  3. Dale

    Dale Active Member

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  4. hmangphilly

    hmangphilly Floppy Quick Phil

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    You still can't go sloshing it around places that any other lube shouldn't be in .

    Krytox is good , and slippy and expensive , but it will ........errr ..........burn ?........diesel? .............combust ? ........dunno the terminology .

    Best kept behind the piston seal .......
     
  5. Dale

    Dale Active Member

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    Well, I have used it on piston seals and didn't have issues with dieseling.

    The manufacturers specs also say non-flammable, so from the experience I have had with it it seems to be suitable for the application.

    At the cost of it 'sloshing it around' is not order of the day.
     
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  6. RobF

    RobF Administrator Staff Member

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    Never seen it smoke. But had a feint whiff that can be best described as a soapy smell. Really feint though, gone after a few shots after a re-lube.

    Seems to do the trick. Wouldn't mix with Moly, use one or other.
     
  7. Amac

    Amac Active Member

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    I have read Gary's comments about Krytox in the magazine. If I remember rightly, is this lube preferred due to its ability to not be bothered about temperature and therefore more likely to result in good consistency?
     
  8. Nick G

    Nick G Active Member

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    Krytox , ultimox and finish line , will all burn given the right conditions ( or wrong conditions depending on your point of view ) I have had them all burn in early reduced bore experiments , every thing has a flash point , all you need is fuel ,air, and heat ( pressure ), if it burns, alter one of these conditions to stop it.
    Having said that in a standard or mildly tuned gun, they will all be ok, oh & finish line bike grease is hugely cheaper than the others .
     
  9. TenMetrePeter

    TenMetrePeter Paper punching member

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    I seem to remember as a teen that sewing machine oil was the combustible of choice to pop in the pellet skirt to make the pellets go with a real bang, sparks and all!
    In more mature times I used to rebuild my webley collection pistons with moly paste and springs with moly grease and oil never came near them.
    Not sure I would spend 30 quid a tube on the new stuff mentioned above.
     
  10. Nomads HFT

    Nomads HFT Well-Known Member

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    Wouldn't put it in a springer compression area, Andy. According to the manufacturers, it breaks down at 400C (~290psi, the start pressure of H&N FTT), and is 9.8% oxygen by mass.
     
  11. RobF

    RobF Administrator Staff Member

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    The presence of oxygen doesn’t mean combustion though. There’s 20 odd % in the atmosphere to start with.

    Nonflammable
    Standard KrytoxTM lubricants contain only carbon, oxygen, and fluorine; whereas, hydrocarbons contain hydrogen The absence of hydrogen greatly increases the stability
    of the lubricants and renders them nonflammable with no flash point They will not burn or support combustion, even in an environment of 100% liquid or gaseous oxygen

    Source

    https://www.chemours.com/Lubricants/en_US/assets/downloads/H-58505-4_Krytox_Overview_LowRes.pdf
     
  12. hmangphilly

    hmangphilly Floppy Quick Phil

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    I wouldn't put any thing in the compression area either .

    Why would you want to ?

    Current thinking is

    if you need additional lube in there other than what can migrate past the seal , you have other issues
     
  13. poth

    poth Whafta old Gits world champion

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    Graphite powder is the new thing totally dry lube and no its not flammable
     
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  14. DeanB

    DeanB Active Member

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    Might be worth checking about using graphite powder. I think it is combustible in air under some conditions.
     
  15. Nomads HFT

    Nomads HFT Well-Known Member

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    I'm aware of that, Rob, having read the data sheet. My issue is that it starts to break down at 400C (around 89% into the compression stroke), and there's no information on what happens to it at the higher temperatures that follow. I am concerned not knowing how the 9.8% oxygen will behave >400C.

    Phil: I always clean all traces of grease from the cylinder, use lubricant on the side of the piston seal, and around the front piston bearing, NEVER directly onto any part of the cylinder wall. As the piston seal is drawn back, some lubricant is left within the tiny holes in the surface of the cylinder. That's all that is needed to reduce seal kinetic friction, by around 50% compared to running the system bone dry.
     
  16. RobF

    RobF Administrator Staff Member

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    Even though oxygen is present in the compound it doesn’t mean it’s going to break down into such and that it’s goimg contribute to combustion of the remaining material.
    Even then there’s plenty of reactions which produce oxygen even with reactive elements present but don’t produce combustion and plenty where if you change the environment you do.

    Given that it warns that breakdown over 400 degrees can cause eye or breathing irritation I’m not sure it would omit combustion.

    If all it does is add 10% of its weight to oxygen in the atmosphere then the only thing that could burn is the seal.

    I guess if you’ve got the kit to take precautions you can see what it does when heated above 400 degrees C. We only know what we know.
     
  17. Nomads HFT

    Nomads HFT Well-Known Member

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    Only ever seen one springer lubricated with this, Rob, a TX200 that had suffered significant muzzle energy drop (to about 720fps with 8.4 gn pellets).

    The front breech seal looked as though someone had played a blowtorch on it. That could have been due in part or in full to the stroke having been reduced to 80mm, the piston mass having been reduced to 155g (both of which necessitate a rise in peak cylinder pressure to compensate), or the lubricant could have had an effect. I just don't know.

    What we do know is that, as long as the transfer port length relative to its diameter is enough to support choking, the temperature drop across the port will be in the region of 14% in Kelvin, the measured example being from 700C to 568C. If the temperature at the outlet was enough on its own to fry the seal, goodness knows what it was in the cylinder.
     
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  18. RobF

    RobF Administrator Staff Member

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    Hi Jim there’s plenty of springers using it on the FT circuit and I’ve personally run a pretty short stroke with it myself. At the moment I’m running a long stroke 21mm though with an o-ring.
    Ive been running various tunes with it over the past few years and the only time I’ve ever had a detonation was using a completely different lube.
    Last year when I was destruction testing a tune I think I put about 1500 through a Krtox tuned 21mm in about 36 hours but most would have been in 2 sessions of a few hours.
    That was with again an oring setup.
    I can’t remember what I lubed with in Portugal but in short term I’ve had a few varieties of plastic heads on pistons and have shot most enough to see a shift in a single session which suggests to me they’re heating up.

    So far the only thing I’ve ever noticed on a rebuild is the smell of soap after a few shots. I can’t remember seeing any smoke and the things have been apart several times without any signs of combustion.

    Think about it this way, Ally almost instantly forms an oxide on its surface, meaning it’s surface, three oxygens for every two aluminium’s. But even though you need to get it up to 2000 deg for anything to happen all it does is melt. But as we know it’s also a component in explosive.

    I realise that 400 is the upper knowledge for the manufacturers statements but it being designed and sold for high temp use, saying it’s non combustible and there being no mention of it being so despite other warnings, and not having seen any evidence of it being so leads me to suspect it isn’t despite it having Oxygen in its compound it’s not going to cause combustion.

    Hopefully even 5-600 deg isn’t out of the reach of someone with the kit to test it safely. Perhaps we can put another unknown to bed then.
     
  19. Nomads HFT

    Nomads HFT Well-Known Member

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    The cylinder temperature that will accompany the pressure at which a .177" RWS Hobby isn't far off 600C, Rob, so that's easy enough to test; a .177" Superdome would be circa 530C, but neither is peak cylinder pressure.

    What we don't know is the pellet acceleration in the barrel to the point of piston bounce, which would allow peak pressure and temperature to be calculated. I did some experiments with a TX and HC last year that suggested each different pellet has its own acceleration profile.

    Maybe the oxygen rich lubricants are OK. I had a bad experience using a PTFE in suspension lubricant in the mid-1980s, so I'll admit to a bit of prejudice, and a reluctance to be a pioneer with new cylinder lubricants.
     
  20. Nomads HFT

    Nomads HFT Well-Known Member

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    That first sentence should have read ...at which a .177 RWS starts to move isn't far off 600C...
     

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