PDP series flow-rate indicators are ideally suited for continuous monitoring of flow for water, HCl & NaOH and air. The fluid flow raises a diver in a conical tube, expanding the cross section of the passage of fluid. The diver moves up proportionnaly to the flow-rate. The PDP rotameter must be installed vertically with rising fluid. It is recommended to have a length upstream of 10x DN and a length downstream of 5x DN.