Common use of Filtration Clause in Contracts

Filtration. All air induced into the space (both outside and recirculated) should be filtered using a medium efficiency (30% or greater by ASHRAE Dust SpotTest) filters. On rare occasions the medium efficiency filter may not prevent build-up of particulates on or inside the equipment cabinets at an unacceptably high rate. This can be caused by the presence of unusually fine particulates or very large amounts of average size particulates. In either case the remedy is to use filters of a high enough efficiency to give satisfactory performance. Filters should be changed at least once every six months (or more often if recommended by the manufacturer), or when filters are so "loaded up" that the fan system can not maintain proper room pressurization as described below.