If feed flow is below normal and the distiller feed pump discharge is normal, the first-stage flash orifices may be plugged. Fouling of the second-stage orifices may be evidenced by water backing up into the first stage; however, the second-stage orifices are larger and will not be as readily plugged. Water backing into the first stage may also be caused by insufficient pressure dif-ference between the stages.

Since the temperatures that exist in the feed boxes are well below the range in which saltwater scale forms, the only plugging or fouling expected at the orifices would come from the introduction of foreign matter into the system. Should the orifices in either stage become plugged, it will be necessary to remove the access plate at the front of the unit, remove the perforated plates from the feed box, and remove the obstructing material from the orifices. The feed boxes are constructed so that the front can be readily removed for access to the orifices.