Ring Lubricator Compressor for Instrument Air Service

Some instruments work better with dry (-40degC dewpoint?) instrument air that has been lubricated by passing it through an oil bubbler, so the particular application determines the particular practice.

And certainly there are some instruments which need oil free air. The purpose of query is to identify the potential hazards involved.

Experts are requested to respond.

SAFETY. Compressing air generates heat. Oil +air +Heat =Fire/explosion

see discussion in this thread:

http://cr4.globalspec.com/thread/20048/Difference-Between-Plant-Air-and-Instrument-Air

Most instrument air systems that I ever had to specify/purchase a compressor for in a chemical plant or refinery were required to be oil free or mini-lubricated compressors. Our instrument group generally always specified this to eliminate the possibility of any instrument being adversely affected by residual oil film or worst yet softening of a diaphragm, depositing on a particular type of electronic sensor, etc.

A separate dryer was then installed after the compressor to insure that the dry bulb temperature of the instrument air system was low enough to prevent the formation of any ice crystals or condensation during periods of low temperature.