ok went to a yard sale and ibought this old thing i thought was vac pump its old but it still pulls down to 15 to 20 suction ins hg. at least that is what the gauge says.the lable on the side says it is a rotary compresser .can any one tell me if this is a vac pump.if not what the hell is a rotary compresser and what it is used for.thank you very much.
who,what,where&when