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Re: ARO Needle Valves vs. Nupro

I would much rather have the more expensive metering valves such as the
Nupro S series (BSS4) however the problem is that they cost $75 Cdn
each. I need four (at least) to set-up some new tanks and so I've
contacted the Ingersoll-Rand distributor (which markets the ARO valves)
here in Vancouver. I don't have a current price yet.

The less expensive valves such as the ARO NO1 (part # 104104-NO1) have a
full open valve coefficient Cv of about 0.04 whereas the Nupro S series
has a Cv of about 0.004 which means that it is much easier to precisely
set at the very low flow rates we desire. The reason these valves are so
expensive ($75 - $100) is that they require extremely precise machining
and have very fine tolerances.

I'm afraid I have to disagree with Dave Gomberg's statement about the
stability and safety of the NO1 valve. I have never had an incident of
the valve releasing excessive CO2. The tendency is for the flow rate to
decrease after adjustments, not increase. This means that there is no
danger of an overdose. As far as stability, once you fiddle with the
valve enough so that the bubble rate is approximately what you want,
allowing several hours to stabilize thermally, it tends to stay at that
spot, at least in my experience.

If money were no object, I would go with the Nupro S series every time.

If you live in Vancouver, you can get Nupro valves in a couple of days
from Columbia Valve & Fitting Ltd., the Swagelok distributor in
Vancouver. ph (604)986-5251
Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!