Аннотация:The kinetic Smodel is used to study the steady rarefied gas flow through a long pipe of variable cross section joining two tanks with arbitrary differences in pressure and temperature. The kineticequation is solved numerically by applying a secondorder accurate conservative method on anunstructured mesh. The basic quantity to be computed is the gas flow rate through the pipe. The possibility of finding a solution based on the assumption of the plane cross sectional flow is also explored.The resulting solutions are compared with previously known results