The Double Case PD Flow Meter consists of an outer casing with measuring capsule fixed inside. The measuring capsule consists of a bulk meter body, rotor with vane blades and two internal covers. Outer end cover and manifold, bolted to the outer casing, form a closed chamber around the measuring capsule to keepit under equilibrium pressure all the time. The product enters the Flow Meter measuring capsulethrough the manifold inlet and at the same time fills up the space between the outer casing and the measuring capsule. This effectively pressure balances the measuring capsule and prevents distortion due to line pressure fluctuations to ensure a high metering accuracy. The separate manifold design further enhances the performance and accuracy by preventing distortion due to pipe line stresses.
The liquid on entering the measuring chamber causes the rotor to revolve by exerting pressure on the vane blades. The proximity of the rotor to the body forms an efficient seal, while the profile of the body ensures that the vane blades are guided through the measuring crescent. The vane blades divide the liquid into segments and each revolution of the rotor displaces four such segments. The rotor spindle transmits the drive through a pressure tight lip seal in the meter front cover to the pulse \ transmitter or the calibrating mechanism, which calibrates the meter output for a corrected counter readout. All mechanical Double Case PD Flow Meters are fitted with Veeder Root mechanical counters.