Patent ID: 7410348

Claim:
A pumping/compressing apparatus for use in a fluid handling system transferring a fluid from one location to another location or to an end user, said pumping/compressing apparatus comprising a multistage device and a motor, the fluid handling system comprising a vessel for holding the fluid, a vapor valve and a liquid valve, the fluid comprising a liquid, gas and/or combination thereof, the vessel being coupled to the vapor valve and to the liquid valve, the vapor valve and the liquid valve being coupled to said multistage device, whereupon gas from the vessel may flow to the device via the vapor valve and liquid from the vessel may flow to the device via the liquid valve, said multistage device being arranged for pumping and/or compressing the fluid, said multistage device comprising at least one reciprocating piston, a first stage chamber, a second stage chamber, an inlet, and an outlet, said inlet being coupled to said first stage chamber, said outlet being coupled to said second stage chamber, said piston including a portion in communication with said first stage chamber and a portion in communication with said second stage chamber, said first stage chamber being arranged to be brought into fluid communication with said second stage chamber, said piston being coupled to said motor and arranged to be reciprocated at respective first and second speeds, said second reciprocating speed being higher than said first reciprocating speed, whereupon when said at least one piston is reciprocated at said first reciprocating speed said multistage device can effectively pump liquid or mostly liquid fluids from said second stage chamber to said outlet and when said at least one piston is reciprocated at said second reciprocating speed said multistage device can effectively compress gas or mostly gas fluids in said second stage chamber and provide said gas or mostly gas fluid to said outlet, an annular recess positioned on said piston in fluid communication with a blowby port by a fluid passageway formed within the piston, said at least one piston including at least one piston seal selectively isolating said second stage chamber from said annular recess and thereby said blowby port, said piston seal being arranged to selectively operate to enable a blowby portion of the fluid in said second stage chamber to flow to said annular recess and said blowby port.