Gear pumps can be used on applesauce, but not apple pie filling. Since liquid moves axially in a PC pump, it is easy to add feed mechanisms, like augers, to enhance feeding materials into the pump. . While it can be conceded that gear pumps can be used for very high temperatures, it is our opinion that no pump is better for ambient temperature high viscosity applications than a PC pump. These devices will ensure that the product enters the pumping chamber. These have to be fitted to gear pumps as an external device, normally at a prohibitive price.
Users have to be very careful about viscosity measurements and statements.
Most pumped materials are non-Newtonian and temperature dependent. A viscosity measurement without the shear rate and temperature parameters is almost useless data. Most viscosity measurements are made with rotational viscometers that only generate up to 50 sec-1 of shear. If the material is too thick to fill the pumping cavity in the time that the cavity is open, the pump will cavitate. That means pulsation, separation of the more volatile compounds in the fluids and non-proportional changing of flow rates with speed changes.