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