A pumping/compressing apparatus for use in a fluid handling system transferring a fluid from one location, e.g., a tank, to another location or to an end use is provided. The apparatus basically includes a motor and a multistage, e.g., two stage, device including at least one reciprocating piston, an inlet stage chamber, an outlet stage chamber, an inlet, and an outlet. The piston is arranged to be reciprocated at multiple, e.g., respective first and second, speeds. The second speed is higher than the first speed, whereupon when the piston is reciprocated at the first speed the device effectively pumps liquid or mostly liquid to the outlet. When the piston is reciprocated at the second speed the device effectively compresses gas or mostly gas fluid and provides it to the outlet. A blowby port may be provided to provide blowby fluid back to the tank or the device.