4.5.4 Total Hydrocarbon: Oil Aeroso

4.5.4 Total Hydrocarbon: Oil Aerosol and Oil VaporTotal hydrocarbon includes both oil aerosols11 and oil vapors12, which are detected differently. Both types are typically associated with oils introduced as part of a compressed air system as oils are typically not present in cylinder based systems. The selection of a sampling method is dependent on the anticipated level of oil expected from the point being sampled as well as whether the oil would be present as an aerosol or vapor.The total hydrocarbon content within compressed air systems is typically addressed through the use of design or engineering controls by installing oil free compressors, which eliminate the vast majority of hydrocarbon and related issues. Some compressors are oil free, but there may still be components within the compressor that utilize oil. Removal of oil aerosols from these systems is performed through the use of coalescing filters located in the distribution system. Where design or engineering controls are in place, oil aerosols are not typically expected to be present in the system and annual or less frequent testing or monitoring is required.Methods for sampling include the use of pre-weighed filter membrane(s) or detector tubes. When using filter membranes, install in a suitable holder with subsequent analysis by gravimetric or infrared techniques. Obtain a sufficient air volume to provide reliable results at the limit of detection.Should oil aerosols not be effectively removed, they may accumulate and coalesce into larger oil droplets and eventually into oil liquid that may become visible. If oil liquid is observed, the system must be immediately shut down and the cause of failure determined as oil liquid is intolerable in pharmaceutical manufacturing.