A mud pump or drilling mud pump is used to circulate drilling mud on a drilling rig at high pressure. The mud is circulated down through the drill string, and back through the annulus at high pressures. Mud pumps are typically positive displacement pumps, otherwise known as reciprocating pumps. Positive displacement pumps are able to provide a constant flow rate of fluid regardless of the pump’s outlet pressure. Duplex, triplex, and quintuplex pumps are all used as drilling mud pumps.Mud pump packages are driven either by an engine or motor. Depending on fuel and energy available on or near a drilling rig, electric motors or diesel engines are common. In some cases, natural gas or other fuel types may be used. Drilling mud pumps are packaged on skid type units which allow for easy removal and transportation from site to site. Other methods are available but are less common.A mud pump system generally includes a charge pump. Due to the high viscosity fluid, additional pressure is commonly needed on the inlet to the mud pump to prevent cavitation.