Re: Needle Valves

["Eric Wahlig" <ewahlig at hotmail_com>]

Jerry asked: >Is there a better needle valve out there for a good price?

I have tried a few of the cheaper valves; none with any measure of 
reliability. The ARO NO1 (about $13.50) just has too much flow. It may be 
called a needle valve but it is not a precise metering valve. I actually got 
one to work for about 6 months but it took a while to get adjusted and any 
room temperature change caused it to fluctuate a lot. This wasn't too much 
of a problem when it was used on a large aquarium that could absorb the 
fluctuations more evenly (large tank=better stability) but it killed several 
fish in a small tank setup by CO2 overdose. The valve simply is not designed 
for applications that involve a very small volume of gas delivery at a 
steady rate.

I had been considering either the NUPRO/SWAGELOK "S" series metering valve 
or the PARKER HR-0 or HR-1 but was dismayed by the price (Nupro-$47). After 
babysitting the ARO's, and others, for a couple years I finally bought the 
NUPRO "S". I also had to purchase the 1/8" MPT adapter to connect it to my 
regulator and their smallest hose barb adapter; fits 3/32" ID tubing. If I 
remember right, these parts cost  $8 or $9 apiece. So, as you can see, it 
isn't exactly inexpensive but the value is there. When you ask: Is there a 
better valve for a good price? I have to say that this is it. The PARKER 
valve is probably as good or better. I think they are a bit more expensive. 
You get what you pay for. This valve runs worry free and is highly 
adjustable. They are not designed for shutoff but the bubble rate can be 
adjusted so slowly that it is, in effect, shut off. This valve has been the 
answer to controlling CO2 flow in a small soft water aquarium without 
resorting to a pH controller.

Eric




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