Rotary vane pumps use positive displacement to move the medium that passes through a pump housing. Inside the pump are a set of vanes that are slotted into rotating rotor which rotates inside the pump housing or otherwise known as the cylinder or barrel. The rotor is normally offset from the center of the pump housing or cylinder causing eccentricity. When the rotor spins, the vanes are forced to slide in and out the slotted rotor with centrifugal force or could be assisted with push rods or springs. The vanes then seal on the pump housing creating vane chambers. On the intake side of the pump, the vane chambers are increasing in volume. These increasing volume vane chambers are filled with fluid forced in by the inlet pressure. Inlet pressure is actually the pressure from the system being pumped, often just the atmosphere. On the discharge side of the pump, the vane chambers are decreasing in volume, forcing fluid out of the pump. The action of the vane drives out the same volume of fluid with each rotation. Because the vanes can be of any given length & varying depth, it makes rotary vane pumps versatile in size and thus versatile in pumping volume. This makes this type of pump useful in many different fields because it can be crafted in such a way to fit the intended usage.