Here are two examples of different ways we ventilate drive enclosures. Notice the one on the left is ducted from the enclosure up through the heat-sink and the one on the left is open at the bottom and has a rain hood on it.
The left one is for indoor dusty environments and the one on the right is for using outdoors. Notice the unit on the right has rain hoods on the enclosure fans as well.
Looking at the front you will notice that there are fans on the bottom of the indoor unit. These fans are "ducted" through the bottom of the enclosure and then exit the back where the air is diverted across the heat-sink. Note also the unit made to go outdoors has a door to protect the keypad and the other pilot controls mounted on the door. Two distinct application, two different ways to protect the drives and keep them cool in the process.
