A commonly used industry standard to set instrument air quality standards is the ANSI/ISA –S7.0.01-1996. As per the described standard.
Pressure Dew Point:
Pressure dew point is described as the temperature at which free humidity condenses for a particular pressure from the atmosphere of the tool into liquid water.
Air dryer outlet pressure dew point should be at least 100°C (180F) below the minimum temperature at which any portion of the IA structure is subjected and at line pressure not exceeding 40°C (390F).
Particle Size:
The IA supplied to consumers is expected to contain particulate matter and a particulate size of 40 mm is acceptable for most pneumatically operated systems.
In cases where, particulate size of < 40um is required, additional air filtration modules can be installed to achieve < 40um sized particulate matter.
Lubricant Content:
Where the air compressor installed in the IA scheme is lubricated with lube oil, there is always a danger of transferring oil along with the compressed air.
This presents a danger to the pneumatic systems receiving air from the tool and affecting their operation. Therefore, the content of the lubricant should be near to 0 ppm but not greater than 1 ppm w / w.
IA System Location:
The location of the Instrument Air system is also important to prevent contaminants, hazardous and flammable gases from being drawn into the Inlet air filters.