Double Case PD Flow Meters

Double Case Positive Displacement Meters have been specially designed to eliminate the effect of line pressure on the metering accuracy. Available in a wide range of flow capacities, the Double Case design ensures a high accuracy along with ease of servicing of “in-situ’.


  • Safe and rugged construction
  • Double case design prevents distortion of measuring chamber due to line pressure fluctuations and ensures high accuracy
  • Easy access to measuring chamber without need of removing the outer casing ensures minimum downtime
  • Unique wear compensating vane design for sustained accuracy over a wide flow range
  • Separate meter manifold prevents pipeline stresses from being transmitted to the measuring chamber
  • Modular construction ensures interchangeable parts lower inventory of spares and ease of service
  • Low pressure drop
  • Mechanical or electronic readout


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 keep it under equilibrium pressure all the time.

The product enters the Flow Meter measuring capsule through 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.


  • Tank truck and rail wagon gantry filling
  • Refineries and high pressure metering in petrochemical, process and chemical industries
  • Blending and batching in lube plants, process control and chemical industries
  • Microprocessor based automation, remote control and data acquisition systems.