In variants, a two-stage pump can include a piston and a cylinder cooperatively defining a first stage in front of the piston fluidly connected to a second stage behind the piston, wherein a forward stroke of the piston pressurizes working fluid in the first stage and forces pressurized working fluid into the second stage, and a backward stroke of the piston further pressurizes working fluid in the second stage and exhausts pressurized working fluid out a pump exhaust.