Patent ID: 8790090

Claim:
A gear pump comprising: at least a pair of meshed gears for rotating within a gear pump chamber, and a motor driving at least one of the gears; a discharge line for receiving fluid downstream from said gear pump chamber, and a suction line for delivering fluid into the gear pump chamber; a bypass valve communicating with said discharge line, and a shutoff valve communicating with said discharge line, said bypass valve opening at a lower pressure than said shutoff valve, and a bypass line communicating the discharge line to the suction line when said bypass valve is open, said shutoff valve opening only when a high pressure is built up on said discharge line; the gear pump being configured to compress air; the suction line may be mounted in either of two attitudes, with the suction line being below the discharge line in one attitude and above the discharge line in a second attitude; a volume of air in an inlet line to be moved by the gear pump is received from a source at a location vertically beneath the suction line in either of the two attitudes; and said bypass line delivers fluid into the suction line through an ejector pump nozzle, with the ejector pump nozzle entraining fluid from the inlet line downstream into the suction line in both attitudes.