Positive Displacement Technology
PD pumps are sometimes called constant-volume pumps because they maintain a constant speed and flow. Even if the system pressure varies, the flow remains constant. PD pumps can handle a variety of fluid types: high, low and variable viscosity; shear sensitive fluids; solids; and liquids with a high percentage of air or gas entrainment. Their capacity is not affected by the operation pressure, and they can be significantly more efficient than centrifugal pumps when handling viscous fluids. PD pumps are able to self-prime, as our dry-lift video demonstrates. Also, with a PD pump you can operate the pump on any point of the curve, and the volumetric efficiency improves at the high speed part of the curve. This is due to the fact that the volumetric efficiency is affected by slip, which is essentially constant. At low speed the percentage of slip is higher than at high speed.