# Source of flashlight-friendly O-ring assortments?



## milkyspit (Jul 27, 2004)

A while back I bought a couple big, bad O-ring assortments from Harbor Freight, thinking I'd be all set with pretty much any O-ring I could need. WRONG! /ubbthreads/images/graemlins/banghead.gif The assortments I bought really do have a wide variety of diameters and even come in nifty plastic organizers to keep things tidy, but I'm finding that the THICKNESS of most of the O-rings is too much for most flashlights.

Does anyone know a good source of O-rings in the narrow thicknesses that most flashlights need? Preferably a whole assortment, or some sort of combo pack at a decent price. I really can't stand a late night modding project grinding to a halt because I need a particular O-ring and have to wait until the hardware store opens in the morning to go searching for the right one. /ubbthreads/images/graemlins/mad.gif

Suggestions, anyone? /ubbthreads/images/graemlins/confused.gif


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## pbarrette (Jul 28, 2004)

Hi Milky,

Try Home Depot for a local source. The last time I was in there I saw a lot of different O-rings in various sizes and shapes (like squared off edges). I can't remember if they had assortment packs, but they did seem to have a lot of the O-rings themselves.

pb


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## gadget_lover (Jul 28, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

My Home Depot has them in the section where they keep the special fasteners, a section of wall filled with little drawers.

My Ace Hardware has a drawer full of O rings in the plumbing section.

It may pay to bring a sample with you to help the clerks understand what you are looking for.

Daniel


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## tvodrd (Jul 28, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

O-ring sizes are "nominal," and typically go by "dash #'s." -004 through -099 are 1/16" cross section. (Actual .070") -100 through -199 are 3/32" cross section. (Actual .103") -200 through -299 are 1/8" cros section (Actual .139") The -300's are 3/16" cross section (Actual .210) -400's are 1/4" (actual .275") I left my Parker manual at work, so this is from frequently-defective memory, and a glance at McMaster who lists a substantial group of sizes. Mag D body sizes are ~$7/100. It's a PITA when you need _one_ but hardware store selections tend to be limited.

Larry


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## McGizmo (Jul 28, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

One other consideration is the material of the O-ring. Buna or Nitrile (sp?) is the most common material and it is prone to O-zone failure rather quickly. EPR or EP or EPDM is a better choice for exposed or unlubricated O-rings but these are not as readily available from the hardware store.


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## tvodrd (Jul 28, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Master,

If I can differ a little, _lubed_ buna/nitrile O-rings have proven quite satisfactory in flashlight applications, particularly for dynamic seals. Static seals don't tend to see much ozone, but a little lube does ease assembly and offer longer life. I think you and I seem to favor silicone? In general, most commercial O-rings will be fine unless you encounter an incompatible lube. /ubbthreads/images/graemlins/icon3.gif (I know _salt_water can add a lot of issues.)

Larry


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## McGizmo (Jul 28, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Larry,

What's this Master sh*t! /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/twakfl.gif 

I agree that lubed buna rings are great in lights and I think lube is a *real* good idea for all of those seals that are accessable and accessed like tail cap and head to tube. However, I have encountered some buna O-rings in window seals, and other places in some lights as well as the external grip applications on the McLux where the buna, not lubricated, cracked and did not hold up well. The isolating O-ring in the SF LOTC is an excellent example of where I have found some "dead" O-rings due to lack of lubrication.

Yes, I like silicone but it does tear and shear rather easy so one needs to pay attention.

Now I am surprised that you, of all people, haven't gone to polyurethane!! /ubbthreads/images/graemlins/nana.gif If you are going to gold plate some parts, what's a few bucks in PU O-rings! /ubbthreads/images/graemlins/thumbsup.gif


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## tvodrd (Jul 28, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Polyurethanes are some remarkable elastomeric, thermoset adhesives! (If you ever need to glue the sole back on one of your shoes. /ubbthreads/images/graemlins/nana.gif ) They aren't happy sealing in wet environments- can be subject to swelling, and aren't as elastomeric as buna. I use them at work for applications that require abrasion resistance, where they are hard to beat. Maybe for flashlights in the "sand box?"

(Master sh*t- maybe I omitted the following 5-letter..... /ubbthreads/images/graemlins/grin.gif )

Larry


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## milkyspit (Jul 29, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Whoa. You guys know your stuff. /ubbthreads/images/graemlins/bowdown.gif

Clearly I do not! /ubbthreads/images/graemlins/ohgeez.gif

Aw man, I just wanted to find some O-rings that actually FIT when I need 'em, without costing me an arm and a leg, and without needing to run over to the hardware store constantly. Build up a stock of my own. But heck, I'm enjoying the learning, too! Thanks guys! /ubbthreads/images/graemlins/blush.gif


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## theepdinker (Jul 29, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Try this place guys.
www.air-oil.com/oringsonlinefset.htm
Theepdinker


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## FNinjaP90 (Jul 29, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Thanks for that site theepdinker!


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## milkyspit (Jul 29, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Theepdinker, thanks for the link! /ubbthreads/images/graemlins/thumbsup.gif

That same website has a nice summary of the properties of various O-ring materials... here's an excerpt...

[ QUOTE ]
*From Air-Oil.com website...*

E70
Ethylene Propylene, EPDM:
EPDM is a terpolymer combining ethylene, propylene and a diene monomer. EP materials offer a temperature range of -65F to +300F and offer excellent resistance to ozone, weathering, steam, water and phosphate ester type hydraulic fluids. EP can be manufactured to conform to FDA requirements, making it ideal for use with foods and medical devices.


N70 / N90
Nitrile, Buna-N:
Nitrile, also known as Buna-N or NBR, is a copolymer of Butadiene and Acrylonitirle. It is the most commonly used elastomer for sealing products. Nitriles have a temperature range of -40F to +250F and are exceptionally resistant to petroleum base oils and hydrocarbon fuels. Nitrile materials also exhibit excellent tensile strength and abrasion resistance properties. Nitrile performs well with most dilute acids, silicone oils and lubricants. It is not recommended for use with ketones, aromatic hydrocarbons and phosphate ester hydraulic fluids.


S70
Silicone:
Silicone materials offer outstanding temperature resistance, from -80F to +400F. Silicone materials provide excellent resistance to sunlight, ozone, oxygen, UV light and moisture. It's inert qualities make it the preferred material for use with food handling and medical applications. Silicones offer poor tensile strength, tear and abrasion resistance, and are not recommend for use in dynamic applications.


V75BR
Fluorocarbon, VITON®:
VITON® is the trade name for DuPont-Dow Elastomers Fluorocarbon or FKM material. VITON® has a temperature range of -20F to +400Fand provides excellent resistance to a wide variety of chemicals. While exhibiting exceptional resistance to chemical attack, VITON® has limited low temperature capabilities. In some applications intermittent exposure to +600F can be tolerated for brief periods of time.


[/ QUOTE ]

Sounds like E70 and N70/N90 might make the best O-rings for flashlights. Then again, what do I know? /ubbthreads/images/graemlins/ohgeez.gif


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## Moat (Jul 30, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Notice no mention of petroleum resistance for EPDM - any of the info I've been able to find generally states it's LACK of resistance to petrol. Buna-N (Nitrile) is probably the way to go (unless you plan on using Silicone greases exclusively?).


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## theepdinker (Jul 30, 2004)

*Re: Source of flashlight-friendly O-ring assortmen*

Have you considered or tryed the Viton o-rings? /ubbthreads/images/graemlins/thinking.gif

Theepdinker


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