CO2 oil filtration

[Woolsocks]

We just converted our air compressor, which drives our keg washer, from oil-free to oiled. This meant installing an oil filter inline between the compressor and the keg washer. It removes oil from the air stream by filtering very tightly - down to .01 micron or something like that, which means we get sterile air as a bonus!

So how come I'm not doing the same thing to my CO2 line from my bulk tank? Would strip out any corn oil that might theoretically make it into my CO2 supply, plus strip out any microorganisms that might be there. Does anyone do this? Good idea?

[brewmaster 2011]

Your co2 in your bulk tank is 99.9% co2. You don't use a motor to compress the co2. It would Just be a waste of money.

[dick murton]

Have to say that I have never speicified oil removal filters, but I strongly suspect that oil removal filters are not manufactured from the same material as gas sterilising filters. As you say, you may get the benefit of sterile gas, but the sterile gas is only at the point of filter discharge.

If your gas mains including the injection point, downstream of the filter are not capable of being sterilised, then you cannot guarantee sterile gas at point of use. To be able to ensure sterile gas, you need to be able to sterilise, normally using steam, both the sterilising filter and the mains downstream, including the injection point, OR, sterilise the filter and a portion of the mains, and CIP clean, inclusing sterilise the injection point back so it overlaps with the steram sterilised part of the system. This split system is very common, perhaps more common than sterilising through the gas injection point with steam as the initial condensate is likely to be discharged into the product pipework, but, that initial condensate is not sterile - it is condensing because the initial metal work it comes into contact with is as say 20 deg C.


Why don't you do it with bulk CO2? Well really you should. The bulk CO2 will undoubtedly be sterile, but the injection system may not be. So all the pressure reducers, block valves, guages etc will be unsterile. So once reduced to working pressure, the gas should sterile filtered and injected through a sterile transfer / injection system. Don't forget non return valves between the point of injection and the filter, and preferably also before the steam injection point pre sterilising filter. I'm not a fan of NRVs, but this is one point where they are a necessary evil.