The Popup Visual Differential pressure indicator PHV2BVN is used to indicate the pressure difference between the input and output terminals of filters, separators, valves, pumps and other equipment. It is especially suitable for indicating the blocking degree of the filter element on the gas pressure regulating and metering station, and for warning the blocking of the filter, so as to facilitate the timely cleaning or replacement of the filter core and ensure the safe and economic operation of the equipment.