Wet clothing secured to ventilation terminals increases the moisture content of the compartment air and restricts airflow. In a clean duct, the cooling effect of the metal tends to act as a flame arrester, but an accumulation of foreign matter within a duct is a potential source of combustion. One method of reducing the amount of dirt and combustible matter which may be carried into a ventilation system is to wet down the deck areas near the air intakes before sweeping. Since a large volume of air passes through or over the elements of a ventilation system, dirt collects in various units in spite of all pre-cautionary measures. Therefore, periodic inspec-tions and consistent regular service procedures are necessary to keep the system clean.
Filters help keep ventilation systems free of dust and dirt.
Navy standard air filters have pressure taps on each side of the filter bank. By using a portable differential pressure gauge, you can quickly read the pressure drop across the filter. When the pressure drop increases to three times that of a clean filter, replace the filter. Ships carry spare filters so that a clean one may be substituted for the dirty one. Special cleaning sinks are installed in ships with enough filters to justify the space, expense, and weight.