I also pump a lot of water through mine after every brew and blow it out with compressed air (with inline oil filter). Then the day before each brew day I countercirculate caustic beer line cleaning solution with a pump designed for beer line cleaning. The output from the chiller (normally the input) dumps into a bucket and the pump sucks up solution from that bucket through a fine stainless steel strainer. At the end of a few minutes of this the solution has turned dark and the strainer is covered with material. After an hour of circulation the solution is much darker and the strainer has a remarkable amount of crud on it. IOW, there is still plenty of material left in the chiller and it's not soluble even in caustic (the crud on the screen does not dissolve). It's probably bits of hops petals that made their way into the system. I have to disassemble the thing one day and clean it properly but it's not a job I'm looking forward to. No infections so far (touch wood) so I guess my protocol has been successful thus far, at least.

This is not a food-grade practice by any means. Filter or not, you are putting oil into your plate chiller.

I got to remember this for when I finally see a well-used Therminator cut open. I'm sure it's gonna be nasty inside (especially since I've seen the Sirron cut open). I have a Therminator, and I know when I see Tasty's cut open, I'm gonna have to keep telling myself, "Tasty said it is ok.... Tasty said it is ok...." just to convince myself to keep using mine.

Don't think so, or if I am it is in quantity so small as to be immaterial or the subsequent cleaning with caustic takes it out. The line from the compressor is long, there are 2 stages of filtering and the second one is especially designed for oil removal. I also use compressed air in my keg cleaning process including using it to blow out the final rinse water. Were appreciable oil entering the kegs head retention would would be effected (unless the steam sterilization I do just prior to filling gets any residue out). I'm also aware of at least one commercial brewery that employs compressed air the same way I do in its keg cleaning line so I'm sure it is food grade practice (though the coalescer and oil filter might need to be labeled "food grade" but that's the nice thing about home brewing - we don't have to worry about that sort of thing). The steam I use for sterilizing (and cooking crabs) comes through a "culinary steam filter" which, I presume, makes that aspect of what I do "food-grade". It turns out that water is the main source of contamination in compressed air systems with oil amounting to 0.1% or less of overall contaminant volume. Most of what people think is "oil" is really water with a bit of oil in it. The dual stage system I'm using is specifically designed to take care of this and is similar to systems labeled "food grade" with similar specs. As nothing ever appears in the bowl of the "coalescer" I just assume that there is nothing to coalesce i.e. that the moisture and oil get trapped in the piping which is installed sloped so that it collects at appropriate points where I have drain cocks. Of course there will be some oil vapor and GAC would probably get that but as I see no evidence of contamination anywhere in the system I'm not likely to install that. So I'm confident that I'm OK even though a bureauocrat might not approve. I use compressed air a lot in brewing. It's much cheaper than CO2. Of course it never touches beer but for pushing cleaning solutions around it's great.

Now that you mention it, I'm probably reluctant to open it up because it may look like crap in there. The manufacturer took down the cleaning instructions from the website but I do recirc a 130F PBW solution for 30 minutes in each direction using my keg/carboy/beer-line cleaner.

Tasty

It's not the use of compressed air that isn't "food grade", it's the type of compressor you are using. An oil-less compressor will provide all the clean air you want. I know about this because I breath off one in my job every single day. The compressor you are using is meant to run pneumatic tools and such. It shouldn't be used in a food/beverage appilcation.

Oil based compressors are fine, i.e. suitable for food grade applications (and SCUBA/SCBA) if the contaminants are removed with proper filtration. There are several manufacturers of filter sets designed to do this specifically for food service, others who make them for SCUBA/SCBA and still others for other applications where oil removal is critical such as spray painting laquer. I happen to have a set of the latter type. From what I can see the main difference is that the filter bodies are not painted white. There is no oil in my beer. In fact I get the lovely, classic meringue like head on my lagers.

From an article by a director of the British Compressed Air Society: "Compressed air users should not be alarmed about the new Code of Practice. The Code clearly confirms that both; oil lubricated as well as oil free compressors are acceptable methods of generating compressed air for use in the Food Industry. Companies who are already using oil lubricated compressors in their food production process should not panic and feel that they have to rush out and purchase an oil free compressor. " Note that while this is the UK it appears that the ISO is driving the bus here. It's also interesting that most hits when researching this are from the UK. Perhaps they take this more seriously over there than we do here.

Further reading at http://www.processingtalk.com/news/prk/prk231.html may be of interest. This article again emphasises that it is water that is the main issue because it harbors bacteria. When they (UK CoP) want dry air they want really dry air i.e. a DP (at pressure) of -40 °C. So it is mostly water that would disqualify me for a food grade certification because I do not have a drier. If I installed one (actually the -40 DP is only required if the air comes in direct contact with the food and I never let that happen with beer because of another contaminant: oxyger) and swapped my oil for food grade oil my old Husky would qualify (I'm not about to do either). I've never been concerned about oil but have never thought about bacteria. As my kegs (that get blown out by compressed air) are subsequently steam sterilized and my fermenters subject to sanitizer rinse followed by a boiling water rinse I don't think I have to worry about bacteria in my air system either.

Sounds like a Session show idea. Eff Tasty's plate chiller to hell with a chainsaw. Pure golden radio.