If p1, is the pressure of air entering the L.P. cylinder and p2 is the pressure of air leaving the L.P. cylinder (or intercooler pressure), then the ratio of cylinder diameters for a single acting, two stage reciprocating air compressor with complete intercooling is given by (where D1 = Dia. of L.P. cylinder, and D2 = Dia. of H.P. cylinder)

• D1/D2 = p1p2
• D1/D2 = p1/p2
• D1/D2 = p2/p1
• none of these