What is Drihold Ventilation System for preventing Sweating of Cargo ?

  • System of cargo space ventilation and humidity control is designed to enable the cargo spaces to be ventilated by outside air or sealed off from outside air as required, to prevent ship’s sweat or cargo sweat respectively. Apparatus for dehumidifying the air in the hold is also introduced. Equipment consists of a Drihold Ventilating Unit having
  • a reversible fan which enables the unit to supply fresh air to the cargo space, or exhaust the vitiated air from the cargo space.
  • drying unit, where the moisture is condensed out from the air by means of dehumidifying coils, fed with cold brine from a refrigerating plant.
  • A heat exchanger, arranged over the coils, warms up the chilled air leaving the dehumidifying coils by extraction of heat from the air entering the drier.
  • When VENTILATING, (Dew Point of outside air is lesser than Dew Point of space), the air is drawn through the natural ventilator and passed around the space to be exhausted by the Drihold unit and delivered to atmosphere.  
  • An arrangement of valves in the Drihold unit enables the cargo space to be sealed off from the atmosphere, under which conditions the fan in the unit draws entirely from the space and returns air to the space to be recirculated continuously.
  • The Air Drying Unit can then be introduced into the air circuit in order that any moisture emanating from the cargo may be condensed out and thus prevent the Dew Point from rising in the cargo space. Two Dew Point sensitive instruments, one-outside air, and the other air-cargo space, (dial, pointer), indicates whether VENTILATION should be adopted, or the holds sealed and RECIRCULATION OF THE AIR, with drying introduced.


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