With reference to your compressor question, my experience indicates that wet seal type once working correctly are much more reliable, the number of times i have heard of contaminated dry seals causing expensive plant shutdown is suprising.
the dry seals are now becoming the default mech seals application ..i know a good number of large centrifugal compressors with dry seals ...running trouble free...
as long as the buffer gas source and instrumentation around the seal is well designed ...then the seal should be ok ...buffer gas should have a dual filter element before going to seal ....
as the trend is to opt for dry seals as opposed to the classic wet film ...i start hearing og mag bearings versus lubed ones.....