A flow limiter or flow restrictor is a device to restrict the flow of a

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...

, in general a

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

or a

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...

. Some designs use single stage or multi stage

orifice plate An orifice plate is a device used for measuring flow rate, for reducing pressure or for restricting flow (in the latter two cases it is often called a '). Description An orifice plate is a thin plate with a hole in it, which is usually placed in ...

s to handle high and low flow rates. Flow limiters are often used in manufacturing plants as well as households. Safety is usually the main purpose of using a flow limiter. An example is manufacturing facilities and laboratories using flow limiters to prevent injury or death from noxious gases that are in use. The flow limiter prevents gases from causing injury or death by reducing its cross-sectional area where gas flows.

Uses

* Reduce flow of fluid (velocity) through a system, e.g. to reduce water usage in a shower * Reduce the amount of gas passing through a system * Reduce pressure in a system * Applications in medical instrumentation * As a

safety valve A safety valve is a valve that acts as a fail-safe. An example of safety valve is a pressure relief valve (PRV), which automatically releases a substance from a boiler, pressure vessel, or other system, when the pressure or temperature exceeds ...

to provide limited flow after closing in the event of a broken hose. (See '' Hydraulic fuse'').

Specifications

*Orifice diameter *Flow tolerance *Media temperature *Maximum flow rate for liquid or gas *Maximum pressure

Design

Flow limiters are designed with the intent of reducing the cross-section area with a plate and a laser drill is used to create a small hole. The diameter of the hole will vary based on the flow rate, inlet pressure, and outlet pressure. The design can also be created with drilled orifices with threaded ends. Another flow limiter design option is the use of porous media. This design is created with hundreds of pores within a central plug. The porous media design has the purpose of lowering the velocity of flow and the lifespan is extended with lower rates of erosion. The disadvantage to the porous media design is the poor removal of particles and a drop in pressure. Debris buildup will not be a concern with the porous media flow limiter with multiple holes allowing liquid or gas to flow with ease.

Features

Flow limiters have features that may be added to expand on their applications. The device can have bi-directional flow and have increased flow control with multiple openings. Flow limiters can also be made of various materials to better improve quality and applications. The materials involve the use of metals, metal alloys, and thermoplastics. Metals like

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

and

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

are materials that have good conductivity with heat and electricity.

Stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...

has the material strength to withstand high pressures and resists chemical corrosion. Flow limiters are also capable of being designed out of

nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from petro ...

and fluoropolymers. For the connections to the flow limiter, there are a variety of ends featuring plain ends, pipe clamp ends, flanges, and compression fittings.Flow Orifices and Flow Restrictors Information
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References

Hydraulic engineering Plumbing Pneumatics {{Tech-stub

Uses

Specifications

Design

Features

See also

References