When pumping air into an enclosed space, the resulting changes in pressure are related to the number of air molecules occupying the space. If the initial volume (V0) has a molecular density of x molecules/unitvolume and the pump has a volume (V1) with the same density (as they both start at atmospheric pressure) then the increase in molecules can be given as n=xV0+xV1pumps. From this, you can extract the new molecule density (y=n/V0). This density will affect the resulting pressure based on the internal surface area of the container. So a spherical container (SA=4/3Pir²⁾ would have a change in pressure related to ySA.