The other potential source of hydrocarbon contamination is the pipework, with the associated jointing process used. The engineering specifications call for degreased material, with any threaded joints done without a hydrocarbon based lubricant.The life of the filter element depends on a number of factors, including the filter challenge (i.e., the feed air quality), air temperature, and the air flow rate.The performance qualification model proposed will consider all of these factors. Note that the final filters (Filters C and D) are not rated for oil vapor removal.Initial testing will be pre- and post- the intermediate and from the point of use on the index run (longest pipe run) of each floor of the building served by the system (see Table 10.2).