Abstract: In a compressor which includes an upper and lower head portions and an interposed diaphragm, provisions are made for increasing the service life of the diaphragm by reducing the incidence failure of the diaphragm due to fretting products and airborne contaminants, which collect at the outer edge of the diaphragm which results in stress concentrations at the outer edge of the diaphragm, and specifically by providing a plurality of concentric grooves in the upper head of the compressor to remove the fretting products and gas borne contaminants from build up at the outer edge of the diaphragm.