Most distributors have filter screens in the main piping between the tank and the spray bar. The purpose of these wire-mesh filters is to prevent particles of burned asphalt or impurities from entering the spray bar and clogging the spray nozzles.

These screens should be removed and washed with diesel fuel, or particles should be burned off with a torch. This will prevent a blockage of the flow of asphalt, allowing it to flow under full pressure to the nozzles. On a large project, the filters should be cleaned periodically.