RocketTomato
Enlightened
- Joined
- Jul 20, 2008
- Messages
- 475
Buna-N, A.K.A. Nitrile, based O-rings are safe to use with petroleum products. I am guessing that the majority of the flashlights (and plumbing) out there use Buna-N for their o-rings. Some, however, such as the McGizmo lights, use EPDM O-rings or Silicone O-rings, which are not compatible with petroleum based lubes.
There is a PDF chart from Nye Lubricants, the makers of Nyogel which lists the chemical compatibility of various lubricants with different o-ring materials.
Here is the link to the PDF.
Check page two, the lower left chart. Different types of lubricants are listed along the leftmost column. Different types of o-ring materials are listed along the top. Note that perfluoropolyethers are Teflon like compounds, Buna-N is nitrile and the Nyogels 779 and 760 are synthetic hydrocarbon based gels. For our purposes, consider that petroleum based lubricants behave similarly to the synthetic hydrocarbon based ones.
The only lubricant that is universally compatible with all types of o-ring materials (included in the chart) is the Teflon based one. Silicone lubricant comes in second place. However, though Silicone grease is technically incompatible with Silicone O-rings, it will mostly just cause the silicone o-rings to swell and not an actual failure of the seal as used in most flashlights.
So if you are sure that your o-rings are made from Buna-N rubber, go ahead and use petroleum based lubricants. If you are not sure what your o-rings are made of, use Teflon or Silicone based lubricants to be safe. (Buna-N is a rubber and so is EPDM. O-rings used to made out of natural rubber which, like EPDM, is susceptible to damage by petroleum products.)
Honestly though, chemical compatibility between O-rings and lubricants is really only important in industrial applications where you have elevated temperatures, pressures and caustic chemicals. So, unless you are using the flashlight for diving or some other critical application where seal integrity is extremely important, it really does not matter what you use as long as you do use something. (Spit does not count as a lubricant by the way
)
Pick something you like and stick with it.
There is a PDF chart from Nye Lubricants, the makers of Nyogel which lists the chemical compatibility of various lubricants with different o-ring materials.
Here is the link to the PDF.
Check page two, the lower left chart. Different types of lubricants are listed along the leftmost column. Different types of o-ring materials are listed along the top. Note that perfluoropolyethers are Teflon like compounds, Buna-N is nitrile and the Nyogels 779 and 760 are synthetic hydrocarbon based gels. For our purposes, consider that petroleum based lubricants behave similarly to the synthetic hydrocarbon based ones.
The only lubricant that is universally compatible with all types of o-ring materials (included in the chart) is the Teflon based one. Silicone lubricant comes in second place. However, though Silicone grease is technically incompatible with Silicone O-rings, it will mostly just cause the silicone o-rings to swell and not an actual failure of the seal as used in most flashlights.
So if you are sure that your o-rings are made from Buna-N rubber, go ahead and use petroleum based lubricants. If you are not sure what your o-rings are made of, use Teflon or Silicone based lubricants to be safe. (Buna-N is a rubber and so is EPDM. O-rings used to made out of natural rubber which, like EPDM, is susceptible to damage by petroleum products.)
Honestly though, chemical compatibility between O-rings and lubricants is really only important in industrial applications where you have elevated temperatures, pressures and caustic chemicals. So, unless you are using the flashlight for diving or some other critical application where seal integrity is extremely important, it really does not matter what you use as long as you do use something. (Spit does not count as a lubricant by the way
)Pick something you like and stick with it.
