Clarification please on CGA-540 connection for O2 tank

Hi all,
I recently purchased an oxygen regulator that lets me set flow rate (for consistency) and a welding oxygen tank to go with it. The guy at the welding store said this connection does not use a gasket, yet I have found tibdits online that suggest there may be one.

Is the cylinder-sealing O-ring mentioned here:
http://www.harrisonvalve.com/product.php?id=25

just referring to something between the valve and the tank itself, or should be there some sort of a gasket/washer/o-ring between the valve and regulator also? Even some teflon thread tape? Nothing?

Thanks in advance.

Bueller? Bueller?

Anyway, I thought I should clarify - the guy at the welding store when I picked up my tank was not the normal guy, and I thought I recalled the normal guy asking me if I needed washers when I dropped it off. Good excuse to bump the thread as any I guess right?

Not near an O2 cylinder at the moment.......Got a pic?
It will either seal with a "flare", (male and female), or an O-ring on the cylinder valve.

I don't believe O2 uses a gasket like an CO2 tank, but I could be mistaken.

If the valve has a "captive" O-ring, the mating face / fitting should have a flat surface to seal against it.


Edit:
You can search here for a pic of your valve, and they give pretty good descriptions of what's required for them, but I THINK, the one you mentioned is a "flare" seal.

http://www.rmiorder.com/search/search_query/Oxygen valve/sort_by/part_number_asc/limit/16/page/1

Thanks for the reply. I'm not home near mine. Here's a link to a regulator like it though:
The threaded nut portion on the reg is loose until you have it threaded onto the cylinder valve.
http://www.amazon.com/dp/B002J7FLTW/?tag=skimlinks_replacement-20

The valve looks like this:
http://www.gmcscuba.com/images/Products/46130OX.jpg

In fact, this image quite accurately depicts the connection.
http://www.concoa.com/images/CGA/cga540.jpg

I'm leaning toward it needs no gasket, but want to be safe and also not waste O2.

Thanks

Here are the actual parts I just took pics of:




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In case anyone else is looking for this answer in the future, it's no washer required.

http://www.williamsbrewing.com/OXYGEN-REGULATOR-FOR-WELDING-TANK-P3476.aspx


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