If it is going to be a small bore valve (under 4") and a characterized V Seat is acceptable then I would like to MCF Valve. check out tycovalves.com for more information
Mighty,
Depends on the application!
Hard Chrome Plating is common in ball valves for corrosion resistance. If you have a abrasive or scaling media look into nickel alloy overlay rather than chrome.
cgair,
Assuming you have a PV vent:
You may want to check the PV Vent parameters and resize the valve to double check
I.E. Vaccuum Setpoint, Pressure setpoint, flowrate (SCFH) in/out, etc.
Anderson Greendwood Varec makes a great sizing program to make calculations much easier and accurate.
You might look at the Descote Valve manufactuered by Tyco Valves and Controls. These valves are a bellow sealed globe valve designed for services such as Chlorine, Phosgene, etc.