O-ring Question for the Modders. What material

[JonSidneyB]

O-ring Question for the Modders. What material is most commonly used in Flashlights. I have found several suppliers and I do not want to make a mistake as I will be ordering 200. Also, I am going to have to measure and existing o-ring I took from a flashlight, do you think I need to account for stretch of the material in my measurements? I figgured I would go one size below what the O-ring measred out to be and stretch.

 

[McGizmo]

Re: O-ring Question for the Modders. What materia

If you go to McMaster-Carr and type a search on O-ring, you will see all the materials listed. I think Buna is a common material used but I have noticed if the O-ring is not to be lubed, the ozone will dry and crack the Buna rather quickly. I think EPDM is a good all around choice but you will need to be careful with what lubes you use, if you do use lubes. Silicone is a great material and reasonably impervious but is prone to tear. I think an O-ring used in a static seal like a lens is a different animal than an O-ring that is exposed and receives wear and action every time you replace a battery. I would defer to the material used by the manufacturer if it can be determined. O-rings are a ***** to measure, especially if they are stretched a fair amount in use.

- Don

 

[Chop]

Re: O-ring Question for the Modders. What materia

I got a set of assorted nitril o-rings from harbor freight. Haven't had any problems with tearing or anything, but haven't been modding long enough to give you an idea of how they stand up to lubes and such in the long run.

 

[AilSnail]

Re: O-ring Question for the Modders. What materia

Maybe you can measure the grooves on the light instead?

I remember that the ideal stretch for orings that are on the outside of a cylinder in a bore seal is around 2.5%. I think the link Don mentioned has some info on this.

 

[CM]

Re: O-ring Question for the Modders. What materia

Go with Buna. It's supposed to be able to use petroleum based lubes but I stick with silicone lube anyways.

 

[Ginseng]

Re: O-ring Question for the Modders. What materia

One important thing about O-rings that I've not heard mentioned is this: Consider their replacement as part of your regular torch preventitive maintenance and inspect and replace regularly.

If they're lubed well, you won't have to worry too much about ozone attack. Always use a non-aggressive lube. Silicone grease is always a good bet. In general, it's safe to assume two things 1) over time they will compression set and the seal will be compromised and 2) as you repeatedly open/close/focus, dirt, lint and other detritus will also act to compromise the seal. Again, check and replace regularly.

I just don't see any good reason to risk a $140 light for want of a $1.25 rubber sphincter.

Wilkey

 

[JonSidneyB]

Re: O-ring Question for the Modders. What materia

ok, does anyone know what size to get to fit and ARC 123 Twisty pack???

 

[DaMeatMan]

Re: O-ring Question for the Modders. What materia

Just a question on lubes now that it has been mentioned. I have been using baby oil to lube my o-rings, is this a good idea? It seems to be holding up just fine, but wondering if it would damage the seal over time or if there is something better i could use.

 

[Cougar_Allen]

Re: O-ring Question for the Modders. What materia

I think petroleum products are bad even for the materials that are resistant to them. I use silicone grease -- you can get it at an auto parts store; they call it "tune-up grease."

-Cougar :{)