What are Positive Displacement Pumps?
Positive displacement pumps move liquid by creating a pressure imbalance within a sealed environment. This imbalance causes the liquid to move from one location to another in an attempt to balance the pressure. This type of pump is only used with liquids and is a simple method for creating a constant flow. In positive displacement pumps, there are two cavities: an expanding suction cavity, and a decreasing discharge cavity. At the beginning of the cycle, the suction cavity is smaller than the discharge cavity. As liquid flows in, the suction side expands. This changes the pressure within the pump, which causes the liquid to flow to the discharge cavity in order to balance the internal pressure. As the liquid moves, the suction cavity shrinks, recreating the original pressure imbalance. No shutoff head exists in this type of pump, so care must be taken to ensure that the relief or safety valve is operational. The proper use of this valve ensures that the appropriate pressure balance is
• Positive displacement (PD) pumps are devices that maintain a constant flow without regard to pressure. PD pumps are used when the flow rate of a liquid must be closely controlled. • PD pumps achieve constant flow by drawing in a fixed volume of fluid at a specific pressure into the low pressure region of the pump and forcefully transferring the fixed volume through the pump’s high pressure region into a relatively high pressure receptacle such as a pipeline. • PD pumps are different from the other primary type of pumps used in industry. These are referred to as centrifugal or rotating pumps. Centrifugal pumps are designed to maintain a constant output pressure without regard to flow rate. They are good for many applications where flow rate is not the primary consideration. • CheckPoint only makes PD pumps; we are the positive displacement pump specialists. We are the largest independent specialist in this industry. • CheckPoint pumps are referred to by many different names depending
