3.4.5 Vane pump - Pumpfocus

Vane pump with sliding vanes

Vane pump with sliding or flexible vanes have the typical characteristics of positive displacement pumps. In a sliding vane pump the rotor is eccentrically located in the pump housing. In a flexible vane pump (see Impeller pump) the rotor is concentrically located in the pump housing. The pumping action is created by an eccentric cam located between suction and delivery ports, see figure 3.45a.

In both types of pumps the liquid is drawn into the pump by an increasing volume between the vanes on the suction side, transported to the discharge side whilst trapped between the vanes and forced out by a decreasing volume.

vane pump operating principle — Figure 3.45a

Figure 3.45a Operating principles for a sliding vane pump

The vanes in sliding vane pumps may be controlled by springs or rely entirely upon centrifugal forces induced by rotation. Some types utilize a rotating cam to guide the movement of the vanes.

Figure 3.45b Pump with sliding vanes in the rotor.

There are many types of vane pumps where the vanes are located in the pump casing (stator), figure 3.45c.

Figure 3.45c Pump with sliding vanes in the stator.

Another variant is the sliding shoe pump where the vanes are U-shaped and operate against two separate surfaces one against the rotating cam, whilst another surface slides against a valve disc, figure 3.45d. A vane pump having axial pumping action has already been described, see figure 3.43c sliding vane screw pump in section 3.4.3 Progressive Cavity Pump.

Figure 3.45d Sliding shoe pump

The pump casing and rotors for vane pumps with sliding vanes are usually made of cast iron, gunmetal or acid resistant steel, whilst bronze or glass fibre reinforced PTFE is used for the vanes. Pumps with sliding vanes are suitable for most clean fluids and especially suited for those with entrained gases or those having a wide boiling point range, petrol for example.

Maintenance costs are relatively low due to the ease of replacement of the vanes, even when being used to pump fluids which are somewhat contaminated, waste oil for example. Vane pumps can operate within a large range of viscosity, although it is necessary to compensate the speed, i.e. the higher the viscosity the lower the speed. This phenomenon being common to all positive displacement pumps.

Pumps with sliding vanes are capable of suction heads of 2-5 m and pressure increases normally of 300 kPa but special cases being capable of up to approx. 3 MPa.