Reefer Service

Fresh Air Exchange System (Ventilation)

The Importance of FAE

The primary principle behind FAE is to purge (remove) unwanted gases from the interior of the reefer. These are produced by the produce respiring . The amount and type of gases release vary from produce to produce and therefore the FAE setting will also vary. These gases may cause physiological disorders or increase senescence if not removed.

Purging is achieved by expelling a measured flow of air from the reefer's cargo area to the outside atmosphere and exchanging it with an intake of an equal amount of 'fresh' air from outside the reefer. The amount of air to be exchanged is determined by the degree of opening of the calibrated FAE grill.

In addition, there is a side benefit for some types of commodities -- adding moisture from the outside atmosphere - the amount of moisture depends on the ambient humidity levels at the time.

FAE should not be used in conjuction with temperature settings below zero degrees Celsius (0DegC) or plus thirtytwo degrees Farenheit (+32DegF). Any moisture being carried in the incoming air is likely to freeze and cause icing. Especially to produce directly adjacent to the delivery air outlets. The result, freezing or chill injury to the produce and possible interrupted air-flow caused by the formation of ice.
 

FAE (ventilation) Setting

The subject of Fresh Air Exchange (FAE) is extremely complex because of the various parameters which can effect the rate of air exchange but also the gaseous content of the air and the phsiological effect on the produce.

There are published guidelines for the FAE setting for various types of produce. However, shipper has to state what FAE is required for thats commodity. This will depend on the temperature of the produce, its physiological condition. To a certain extent also the type of packing and stow pattern within the reefer. The FAE amount should always be in Cubic Meters per Hour (CBM/hr) or Cubic Feet per minute (CBF/min) and not expressed as a fraction or percentage as different reefer unit manufacturers may have different FAE settings. Expressed in CBM/hr or CBF/min the setting amount will always be the same but as a fraction or percentage the volume of air may be different:

Ventilation Door Displacement Comparison Table (unit operating with 60Hz power supply)