... 1 positive displacement blower, no compression, air conveying is smooth, there is small flow rate changes along with pressure changes.2 ... life.6 much cleaner with no oil 7 with nitrile rubber seal rings 8 Swedn SKF brearings9 Germany OPTI beltsUsage ... pressure relief valve, pressure gauge, cock, vibration-isolating base, rubber vibration isolator, expansion joint, check valve, commong basement,first ...