air valves on keg washers

[panadero]

Hello,
I am trying to find information on using co2 for the keg washer we have. I know people are doing it, and I can set it up easily enough, but wondered if the co2 will erode the seals in the valves a lot quicker than compressed air. I have seen both yea and nay on this , so thought I would just put it out here. Iwill get an air compressor eventually, and co every third or fourth run with caustic, but should I even worry about the co2 in the air valve system. Should I run the co2 through a filter/dryer the way the air from the compressor goes?
Thanks, I just want to get this set up right the first time.
David

[TGTimm]

Does your keg washer use automated solenoid valves or ball valves? What pressures are you looking at? Teflon-seated ball valves have no problem with CO2. Rubber (including Viton and silicone)-diaphragm or sealed valves can have problems with CO2 at higher pressures. At high pressures, the CO2 saturates the rubber, causing it to swell or burst when the pressure is dropped. Probably any pressure you'd be using on a keg washer isn't high enough to cause this problem, but our primary regulator at 350 psi definitely fails from this when we run dry of CO2. Not every time, but too frequently. I've never seen corrosion problems from CO2 unless water or moisture is involved.

You will probably not want to replace pressurized air with CO2, for financial reasons if nothing else. You do want to final-flush the kegs with CO2 and leave a ~15 psi charge in them for filling.

Using a 50 lb can of high-pressure CO2 will generally not work without a heated regulator, a vaporizer, a tank heater, or all of these. The high rate of usage for a keg washer will result in the liquid CO2 phase-shifting to dry ice instead of gas ("snowing up"), which usually really screws things up.

So buy a good compressor and filter/dryer for most of the cycle, with CO2 purge at the end. And yes, filter the CO2 and air to microbial levels. A dryer should not be needed for CO2.