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[APD] Different needle valve this time.

OK, so no one wanted the last needle valve I offered, I guess I'll put it up
on ebay.

Since the valve I really wanted came in a package of two, I have the extra
one to sell if anyone is interested.

It is a Nupro (by Swagelok) fine metering valve (part #B-SS4). Pictures
here: http://www.satinstrings.org/aquarium.htm [I hope any t-sips out there
are not offended ;-} ].

Here is a link to the spec sheet for Swagelok's metering valves.
http://www.swagelok.com/downloads/webcatalogs/MS-01-142.pdf. It's a PDF
file, so you need Adobe Acrobat viewer to view it.

It looks like (and is) the valve on the far left of the page three. A
cutaway diagram of the valve can be seen on the top right of page two. I
have used the 1/4-inch fittings on standard aquarium airline tubing at low
pressure (less than 10 psig) with very good results. I don't know about
higher pressures, but it takes a real strong pull to get the tubing out.

A few relevant specs from the sheet:
- Silver-mist, chrome-plated brass with Buna-N seals and o-rings, and
stainless steel stem.
- maximum Cv of 0.0040 (10 turns to fully open)
- Cv less than 0.00025 at one turn open. That's very fine control, even for
our purposes.

This valve is not rated for full shutoff, however when I blow into the valve
as hard as I can, it takes a long time to make even one bubble. I am told it
is possible to adjust the valve for full shutoff, but Swagelok does not
recommend it, so neither will I.

The valve is $15, plus shipping (probably about $5). In order to minimize
traffic on the list, let me know off-list (email address below) if you are

Douglas Guynn
        d.guynn at sbcglobal.net

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