Air filter Regulator (AFR)

Air filter Regulator (AFR) should be the first component at the inlet of most air circuits like control valves. Air filter regulators are combination of a filter unit with pressure regulator assembly to provide neat and clean regulated air. Since air supply to actuator and other accessories such as I/P converter, positioner, solenoid valve, Booster relay etc. must be clean & dry to increase life of components such devices. So it is necessary to use filter unit along with pressure regulator to remove particles and humidity from fluid is better choice than using regulator alone.

A diagram for air filter regulator is shown as follows-

The basic elements of Air filter Regulator (AFR) is given below-

  • Pressure Reducing Element such as poppet valve
  • Sensing Element such as piston or diaphragm
  • The Reference Force Element to apply necessary force such as spring with setting knob
  • Filter assembly with particle filter/ moisture absorbing filter

Sometimes a separate filter unit can be used in series with pressure regulator instead of Air filter regulator. This configuration also provide same functionality as AFR. Selection of a right AFR is recommended for proper operation of control valves as mentioned below-

  • Fluid to be used for regulation (gas, liquid, toxic, or flammable)
  • Selection of materials in pressure regulators and filter
  • Type of filter and its allowable particle size present in air
  • Operating Pressures
  • Flow Requirements/ capacity & Orifice Size

Here size of particle filter depends on the process requirement and selected as per downside other accessories. 

Read Also:-

Control Valves Accessories

Pressure Regulator

Filter Regulator Lubricator (FLR o FRL)

I/P Converter (Electro-pneumatic Converter)

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