Needle valves for custom phase change

[stasiu]

I've been lookin' all over for something i could use to meter the flow of refrigerant, and think i finally found some needle valves (http://www.aalborg.com/catalog/pdfs/VB%20Valves.pdf) that will fit the bill. I think i'm going to use two VM5-BB-1A's for my dual evap. The only thing i'm not sure of is how the o-rings will hold up with 404A or 507. I'm getting some 404a for free and upgrading to 507 after everything is tuned. Anyway, is anyone familiar with how "Buna-N" or "Viton" o-rings hold up against either refrigerant?.

[Sidewinder]

The valve should be for the gas you will use, if you use a other gas you need a new valve...

[stasiu]

I'm not sure what you're talkin' about, i've been looking a long time and have never found a valve specificly designed for such small volumes of refirgerant. Anyway, i talked to a refrigeration tech and he recommended the stainless steel with viton Orings. He knows of different types of valves that used viton O-rings.

[chilly1]

The issue with those valves may be the Buna-N,PTFE or vitron, you will need to contact the manafacturer for a materials compatibility statment. The 1/16 increment and small size of the valves would make them a possiable choice to replace cap tubes with a hand expansion valve.

I called the Manufacturer. They take credit cards. 95.00 for the VCL-SV-2A stainless with Vitron and it's compatable with R404/507, the temperature range is officially down to -20C. So I think they will work but there may be some issues at lower temperatures. As with all hand expansion devices it will need to be well insulated including the handle, condensation will destroy the valve if water gets between the stem and the seal.

[stasiu]

Thanx...i got the same reply from them too. Like i said though, i've been told by someone i know that he uses some different kinds of service valves with the Viton o-rings. I'm gonna order a pair up and see how it goes.