The present invention discloses a process gas reduction apparatus and method. Process gas abatement device comprises a burner, the burner, it is possible to accommodate the outlet gas stream from a manufacturing process tool to work to be processed in the combustion chamber under a negative pressure, can also act to accommodate fuel, oxidant, and diluent , comprises a combustion chamber, wherein fuel, oxidant, and diluent, and control the combustion in the combustion chamber to produce an exhaust stream treated by treating the effluent gas stream, wherein the diluent is condensed in the process exhaust stream It can be. For example, by providing a diluent in the form of an inert condensable material, it is reduced in volume increases in the combustion chamber, which reduces the volume of the exhaust stream to reduce the volume of the load on the second pump. Volume increase is reduced because the diluent is removed, the contribution of the diluent for the effective volume of the exhaust stream by shifting a phase in the exhaust stream. This leads to significant power due to a gas volume less to a second pressure, for discharge from the combustion chamber in which there is a necessity to increase example to atmospheric pressure by a second pump.