Throttling orifice plate

1. Ensure the safe startup and proper operation of the centrifugal pump. When starting a centrifugal pump, in order to achieve a certain outlet pressure and reduce the starting current of the motor, it is necessary to start the pump with the outlet valve closed or partially closed. However, for certain centrifugal pumps, such as high-head centrifugal pumps and those used to transport volatile liquids, the gap between the impeller inside the pump and the pump casing is very small, which makes it easy for the fluid to vaporize. Therefore, these types of centrifugal pumps require a certain flow rate during startup and operation. If such centrifugal pumps operate without any liquid flow (i.e., in a closed condition), vortices will form inside the pump, causing the liquid to heat up and vaporize, which leads to cavitation or pressure buildup and can easily damage the pump. To ensure the safe startup and proper operation of such centrifugal pumps, it is required that the pump have a minimum discharge flow rate; this value is known as the minimum flow rate of the centrifugal pump. Typically, the minimum flow rate is specified by the pump manufacturer. To ensure a minimum flow rate, a return line is added to the outlet pipeline of the centrifugal pump, known as the minimum flow line. By using a flow-limiting orifice plate on the minimum flow line, it is possible to ensure the safe operation of the centrifugal pump, even in the event that the pump’s outlet valve is closed due to an error, thereby preventing damage to the pump. 2. Replacing the flow control valve to limit the maximum flow rate: In process operations where flow regulation is not necessary and only a limitation on the maximum flow rate is required, a flow-limiting orifice plate can be used in place of a flow control circuit to prevent excessive flow and thus save on investment costs. This is also one of the most common uses of flow restriction orifice plates. 3. Prevent bypass flow in various branches In some cases, the process requires that the flow rates in each branch pipe be equal. However, since it is difficult for the pressure drops across each branch pipe to be exactly equal, there are differences in their flow rates. By using flow control orifice plates, the pressure drop in each branch pipe can be adjusted to maintain a consistent flow rate in all of them.