This is why faster moving doors can be critical in a freezer situation. The faster they move the less chance they stand of being hit by a moving forklift and having their seals compromised.
This brings us to re-circulatory air doors, which aren't doors at all. Instead, blowers blast air across the opening of a freezer or cooler doorway, which stops refrigeration loss as well as moisture migration. The air is sucked in on the other side of the door by an intake device, which recirculates the air.
"One of the big advantages is frost elimination," says Jamisons' Clark. "You're not running all the defrost cycles on your refrigeration systems, which is where your big expense is, because you don't have all this ice forming on your coils."
Air doors present a number of other benefits. Safety-wise, there is the prevention of ice formations on the floor, walls and ceiling, which is a problem in freezers where a great deal of moisture is present. Additionally, air doors provide complete visibility, which cuts down on collisions. There is also a productivity gain-workers don't have to wait for doors to open and are able to move product faster.
However, air doors are expensive and need to be justified from an energy savings standpoint. The initial investment is only offset if a warehouse has a lot of pass-throughs in its cooler or freezer, which translates to high open door times.
"With high open door rates, you have all the effects of not having a door there at all," Clark says. These effects include loss of treated air, influx of moisture and higher energy costs. "The busier you are, the more a traditional door works against you."
Before settling on a door, vendors suggest warehouse managers do their research-they should take a look at what their doing currently in terms of door designs and whether or not it's working. They should also review how many pass-throughs each door is getting, as well as the amount of damage they are subject to. Then they need to consider what it is they wish to achieve with each door.