System and method for in-process integrity test of a filter

The invention relates to a method for in-process integrity test of a filter. The method may comprise the steps of: coupling a gas source to an input side of a filter without removing the filter from a dispenser system, the gas source supplying a gas and controlling a pressure of the gas; coupling a tube to an output side of the filter, the tube being filled with a liquid; increasing the pressure while monitoring the tube, with a light beam, for a displacement of the liquid by one or more gas bubbles; and determining a value of the pressure at which the displacement of the liquid is detected.