A progressive cavity pump moves liquids by turning a rotor and progressing the liquid through a set of cavities through the pump. Material is drawn through an air diaphragm pump when a piston raises the diaphragm. When the diaphragm lowers, a ball valve at one end of the pump closes while another opens at the other end of the pump. This forces the material through the pump, allowing more material to be drawn through the other side.
Progressive cavity pumps and air diaphragm pumps are designed to pump high, medium and low-viscosity liquids. Air diaphragm pumps however, are capable of moving liquids that contain a higher volume of solids. Both pumps can pump sewage, sludge, slurries and acidic chemicals.
A progressive cavity pump is designed to eliminate pulsing. The cavities taper down at the end of the pump and overlap other cavities, eliminating pulsing. The regular up and down movement of an air diaphragm pump's diaphragm causes pulsing. A dampener can be fitted to an air diaphragm pump to eliminate pulsing.