Restrictors

Restrictors are devices or components designed to limit the flow, movement, or intensity of a physical parameter within a system. They are used to control performance, enhance safety, reduce energy consumption, or help meet regulatory requirements. Restrictors can be passive or integrated into equipment, and they may work by creating a fixed obstruction, regulating a variable parameter, or introducing a calibrated resistance.

Common types include fluid restrictors, which limit the rate of liquid or gas flow in pipes, hoses, nozzles, and taps. Water-saving devices such as aerators and showerhead restrictors are typical examples. Engine intake restrictors are used in some motorsports to cap power. Nozzle restrictors and orifice plates provide known flow characteristics and can be used for testing or process control. Pressure restrictors and relief devices limit maximum pressure in hydraulic or pneumatic systems to protect equipment and operators. Mechanical restrictors limit travel or movement of components, such as travel stops or limit switches. In electrical contexts, current-limiting devices serve a similar protective purpose, though they are usually described as current limiters rather than restrictors.

Selecting a restrictor involves considering the target parameter (flow, pressure, travel, etc.), operating conditions, material compatibility, durability, installation location, and acceptable drops or resistances. Performance depends on the geometry of the restricting element, fluid properties, temperature, and system pressure. Restrictors are used across industries—from plumbing and heating to manufacturing and automotive—to balance efficiency, safety, and compliance.