Metering orifice

Metering orifice

A thin plate that is mounted inside a pipe and has a sharp-edged aperture through which the fluid in the pipe is accelerated. The acceleration causes the local static pressure to decrease. The flow rate is sensed by taking one pressure reading upstream and one downstream of the orifice.

The orifice plate is commonly used as an instrument to meter or control the rate of flow of the most common or newtonian fluids. These comprise all gases, including air and natural gas, and many liquids, such as water, and most hydrocarbons. With no moving parts and a simple design, the orifice is easily machined, and thus has been a popular flow-measuring device. However, its pressure loss is large compared to more expensive devices such as the venturi tube.

The metering orifice is one of a class of differential-pressure-sensing devices that are used to indicate flow rate. Others in this category include flow nozzles, venturis, elbow meters, target meters, and wedge meters. In open-channel flow, such as occurs in streams and canals, the weir serves the same purpose as the orifice; however, because the flow occurs at constant pressure, the height of the fluid over the weir, rather than the pressure, is used to sense the flow rate. See Nozzle, Pitot tube, Venturi tube

References in periodicals archive ?
Typically, a custody transfer metering station will comprise one or two runs of pipe with a calibrated metering orifice in each run.
Depending on the application, the metering orifice can be formed with tapered throttling areas on the spool, as shown in Fig.
The Servoid valve driver provides linear proportional control of the metering orifice which yields linear proportional flow.
The available flow is divided in proportion to the opening ratios of the metering orifice areas.
The pressure in the system increases from the set standby pressure to load pressure with the opening of a metering orifice and directly initiates the movement of the actuator with the help of this basic flow.
When the actuators are operated, as soon as the volume demanded by the open metering orifice [SIGMA] Qactuatorss exceeds the basic flow Qmin set on the pump, the system operates above the Qmin flow according to the load-sensing, closed-center principle.
The SREI documented that the square root error at each metering orifice was caused by compressor generated pulsations resulting in metering errors of 6.
Square root errors at the metering orifices were all less than 0.
The setting changes because oil flows from the pilot chamber across a metering orifice into the chamber between the adjustment screw and the pilot sleeve itself.
This creates a constant pressure drop across the metering orifice.
Gasses tapped off the barrel flow down the plug through one of two metering orifices, and cause the cylinder and piston rod to move rearwards.