testing system 10 further includes a flow meter 58 whose operation will be subsequently described flow meter 58 is physically housed within vacuum canister 24 and includes a piston assembly 58a fig3 responsive to fluid flowing through flow meter 58 and a velocity transducer 58b fig5 velocity transducer 58b generates an output voltage signal proportional to the velocity imparted to piston assembly 58a and represents the rate of flow of fluid flowing through flow meter 58 the output of velocity transducer 58b is applied along signal line 60 to data collection and reduction circuitry 62 of the present invention data collection and reduction circuitry 62 will be subsequently described in connection with fig5 8 flow meter 58 is interconnected to control valve 56 through fluid lines 66 and 68 control valve 56 is a manually operated valve and is interconnected to a pressure regulator valve 72 through fluid lines 74 and 76 control valve 56 is operable between a first and second position in the first position of control valve 56 control valve 56 connects fluid line 54 to fluid line 68 fluid line 66 to fluid line 76 and main return line 38 to fluid line 74 in the second position of control valve 56 control valve 56 connects fluid line 54 to fluid line 66 fluid line 68 to fluid line 74 and main.