Advantages of Plant Air and Instrument Air

Instrumentation
1

Instrument Air / Utility Air systems (IA/NI/UA) have same operating and design conditions throughout the plant

They are CAT D fluids that are non toxic /non flammable

Operating Conditions = 860 kPag (Temperature -29 deg C to 186 deg c)

Design Conditions = 1034 kpag

PLANT AIR / UTILITY AIR / SERVICE AIR

  • plant air generally runs anywhere from 60 to 150 psig, and usually has considerable condensate and sometimes particulate.
  • Not dry
  • Normal plant air will be dirtier, contain oil and high humidity - remember a lot of pneumatic tools need the air to have oil in a mist form in the air to lubricate the tool.
  • Utility air is just that, Used for utility purposes. Pneumatic tools, pumps, fans, blowing down hoses….

Usage(some) of Plant air:

  1. Driving equipment’s like Pumps, Fans, Airheaters(in boilers) etc.
  2. Operating Pneumatic Tools
  3. In Oil burners - for atomising and cleaning
  4. In Refineries, Petrochemical and other similar plants where explosive gases presents, for Pressurising Electrical panels to prevent explosive gases entering the electrical panels
  5. For cleaning of Plant machinery.

Instrument Air

  • Instrument air is clean and dry, having been filtered for both particulate and moisture, and runs a normal maximum of 20 psig at the drop, since the typical pneumatic instrument is looking for 3-15 psig.
  • Dry air
  • Instrument air as said above is dry air, its also filtered for fewer particulates and oil is removed…
  • The Instrument air in a plant is used to supply motive force for control valves. In older plants 3- 15 PSIG is used as a signal for control and feedback from pneumatic transmitters and valve positioners to pneumatic controllers in a control room.

That being said the Instrument air supply should be of the highest quality air you can get with compressors and air driers.

Most plants will also have a redundant air compressor and drier for the Instrument side.

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