Differential Pressure Orifice Plates

KPL orifice plate assemblies are commonly used to provide a reliable and often cost-effective differential pressure reference for flow rate measurement in medium to large diameter industrial piping. Because the measurement principle does not have any moving parts, a long service life with minimal maintenance required is guaranteed. KPL orifice plates are available in a wide range of specific constriction methods to optimize compatiblilty with specific application requirements and challenges. Options include concentric orifice plates, bidirectional orifice plates, quarter circle nozzles, conical entrance orifices, segmental orifices, and excentric orifices.

Differential Pressure Measurement Principle

If a pipeline with flowing media is reduced at a particular point by a cross-sectional constriction, the flow speed of the measured media is increased at that point. According to Bernoulli’s energy equation and the law of continuity, the total flow head (dynamic velocity head and static pressure head) is constant. The increase in speed at the constriction causes a reduction in the static head. The resulting pressure drop is called the differential pressure head and may then be used to measure the flow rate (volume per unit of time or mass per unit of time). The flow rate is a function of the square root of the differential pressure across the orifice plate. This rate can then be determined by use of an appropriately scaled differential pressure transducer or gauge.

Total Differential Pressure Flow Measurement Assmeblies Using Orifice Plates

Differential pressure measurement with orifice plates is achieved by the primary constriction element of the orifice plate paired with a differential pressure transmitter which converts the pressure difference before and after the point of constriction caused by the orifice plate and converts it into a standard output signal. Choosing a transmitter, like our PAD Heavy-Duty Industrial Differential Pressure Transmitter, that features an internal square root extraction assures a linear signal.

Integrated Differential Pressure Orifice Flow Meters

If an integral orifice flow meter is desired, KOBOLD offers the RCM Differential Pressure Orifice Flow Meter for liquids, gas, or steam. It offers high flow rate capabilities and is suitable for small to medium sized line sizes. Also available is the KEL Heavy-Duty Differential Pressure Flow Meter for liquids.