I also use the Clippard MNV-4k2 with good success. My only complaint is
that even with only 10-15 lbs pressure, the adjustment controls are not very
fine - e.g. small turns of the adjusting know result in big changes in gas
volume. I wish it were finer.

If I were going to get a Cadillac valve, based on the research I have done,
I would get the Swagelok Brass Very Fine Metering Valve(likely a B-SS4 for
$47.60)
http://www.swagelok.com/PRODUCTDETAI...ice=&Picture=N
PH634CROPstraight%2DS%2EJPG&CTSCKey=69
10 turns of revolution and a max Cv of 0.004


or, probably a better, but more expensive choice would be the Parker HR
series "H1" metering valve which has 15 turns or revolution and a Cv of
0.006.
http://www.parker.com/ivd/cat/English/4170-HR.pdf

I read about a user of the Parker who said "I open it up about 3 turns to
achieve 1 bubble/sec."
See Dan Dixon "More CO2 injection stuff":
http://216.239.57.100/search?q=cache...com/Plants/CO2
/solenoid.html+micro+metering+valve+co2&hl=en&ie=UT F-8
With 15 turns of revolution, this indicates a lot of fine control available
for out application. Not clear of the price. It may be as much as $90 or
so.

--
Bob Alston
918.494.4913

"willis stanley" wrote in message
...
OK, I've had a clippard needle valve blow up on me after two weeks of
operation (around 4 psi coming off the regulator). Well, what happened
was it started hemoraging gas and then literally fell apart when I tried
to tighten the connections a bit. Right now I've got the home depot
special rigged up and putting out 1 bubble every 4 seconds or so.
Assuming this won't last (I'm not messing with it so long as it works)
what sort of other needle valve brands are recommended/used out there?
More importantly, if I have to invest in a more expensive needle valve
some time in the future, what would I likely have done wrong to cause
this sort of failure in the clippard?