ABSTRACT
The working principle, advantages and disadvantages of a number of positive displacement meters (sometimes referred to as direct-volumetric totalisers) in which the defined volumes of the medium are separated from the flow stream and moved from the inlet to the outlet in discrete packages are discussed in this chapter.
Ideal for fluid batch, blending and custody transfer applications, positive displacement meters are able to provide very accurate measurements.
Technologies include:
Sliding and rotary vane meters – used extensively in the petroleum industry for gasoline and crude oil metering.
Oval gear – suitable for a wide range of applications including high viscosity and high pressure and unaffected by changes in viscosity and lubricity of the liquids. Includes paint, polyol, isocyanate, glues, PVC, coating wax, and hydraulic oil applications.
Lobed impeller – designed exclusively for gas applications.
Nutating disc – used extensively in the water industry.
Other technologies include: oscillating piston, axial-fluted rotor meters, and wet gas meters.
