A powder feed apparatus for a powder spraycoating equipment includes a dense phase powder pump fitted with at least two feed chambers, alternatingly discharging coating powder. Each feed chamber includes a powder intake valve to aspirate coating powder during a suction stage and one powder outlet valve to discharge coating powder during a discharge stage. Each feed chamber further includes control valves to operate the dense phase powder pump and a control unit controlling the dense phase powder pump by the control valves. A dependence mode of the total open time (ttotal) of the powder intake valves defines the dependence of the total open time (ttotal) on an adjustable nominal value (mp) adjusted by a powder adjusting element and relating to the rate of powder to be conveyed by the dense phase powder pump, and defining a response delay time (tdelay) and an apparatus constant (C).