The compressor portion of any PET Bottle Blowing System is universally looked upon as a ''Necessary Evil.'' While a Bottle Blowing System layout may be studied for months, the compressors to run the system are often purchased without any special consideration at all. Using the compressor that has always been used, or buying the compressor with the shortest lead time or best price can cost a company thousands of dollars. The compressor is the heart of any Bottle Blowing System. A reliable, correctly sized compressor can save many times the initial system cost when compared to a poorly sized or unreliable compressor. This paper will present some straight-forward steps that can be taken to help a company make the right decision when purchasing a compressor for a PET Bottle Blowing application.