Dock Seals vs Truck Shelters
The most common opening width for loading docks is 8′, but we are seeing a lot of 8’6″, 9′, and even 10′ wide doors being specified with seals. To understand the problems caused by increasing the opening width we must examine the nature and function of a dock seal.
A dock seal, by definition, seals against the back of the truck and restricts access to the truck opening width. Keeping in mind that only some trucks are 8’6″ but most are 8′ wide, the opening on the face of a standard seal has to be less than 8′ to seal against the back of an 8′ wide truck. The standard opening on the face of a seal is normally 7’4″ to 7’6″ (depending on the seal manufacturer) regardless of the door opening size.
If the end user has all 8’6″ wide trucks, the seals can be set up 8′ between verticals.
After examining figure 1, you can see that the ideal opening size for a loading dock door and seal is 7’6″ or less. Whenever full access to the truck opening is a necessary feature, the correct thing to do is use a shelter which goes against the outsides of the truck instead of a seal that goes against the back.