Orifice Plate

An orifice plate is the core of an orifice meter, restricting flow to create differential pressure proportional to the flow rate. Accurate flow measurement depends on the plate’s quality, installation, and maintenance. For wet gas or saturated steam, a weep hole is drilled at the pipe’s inner diameter. Orifice plates are made per ISA/AGA/API/ANSI standards in materials like SS304, SS316, SS316L, Hastelloy C, Monel, or PTFE-coated.

Restriction Orifice Plate: A Restriction Orifice Plate, thicker than a standard orifice plate, is used to reduce upstream pressure by dissipating energy through friction and heat. Single plates are common, but multistage designs prevent noise, vibration, and cavitation at high flow velocities. For viscous fluids and low Reynolds numbers, the upstream side is beveled. Discharge coefficients align with ISO 5167 standards. When noise levels exceed limits, multi-hole plates are used, with the number of holes determined by process conditions. Multistage multi-hole configurations are also available for optimal performance.

This type is not used for flow measurement but for dropping the pressure considerably and reducing the flow accordingly. The bore is not beveled but kept straight. The beta ratio has no limit as accuracy is not the goal.