17.2.5 Fire Dampers
Building codes require that whenever conveyors pass through walls, floors or ceilings, the fire
resistance rating must be maintained. It is therefore necessary that rated fire dampers be
incorporated into the conveyor system. Figure 17-9 shows a typical vertical down-close type
door. The inspector should examine each damper to be sure it will operate in its intended manner
when the need arises. The dampers are usually equipped with 165 degrees F thermal fuse links.
However, other devices, such as the electromagnetic holder with an overriding 175 degree F
thermal release switch or a motor operated holder with thermal override switch may also be
found. The vertical down-close door is closed by gravity. They are the type most used.
However, vertical up-close and horizontal movement dampers are available. They are operated
by a constant force steel spring. Latches are required to retain the up-close damper in the closed
position. Close attention should be given to the guiding tracks, springs and latches. Dirt can
easily accumulate in these areas and prevent the damper from closing properly.
17.2.6 Delivery Vehicles
There are a number of different sizes and shapes of delivery vehicles. Each manufacturer
offers a variety to choose from dependent upon the user's need. However, once a system is
installed, a particular container changing to another shape may not be possible because of
operating clearances. Figure 17-10 shows a composite of various manufacturer's vehicles.
Figure 17-11 shows two of the more popular types of delivery vehicles and points out some
of the major components. Each vehicle contains a 24 volt D.C. motor which is used to power the
vehicle. Power is obtained from the stationary rail by way of collector brushes. The units are
gear driven. The drive system turns both a friction drive wheel and gear wheel. The friction
wheel propels the module along the horizontal and the gear wheel moves it in the vertical
direction using the gear rack mounted in the vertical stationary rail. Figure 17-12 shows a cross
section of the rail and module. The type shown uses an upper and lower wheel arrangement to
retain the vehicle on the track, while other manufacturers use a single wheel and form the track
around the wheel. Continuous maintenance is required on the vehicle components. The
inspector should see that this is being performed. Each vehicle that has been removed from the
system reduces efficiency, and vehicles not operating in peak condition can cause shutdowns.
Another area to check when examining the modules is the closure handle or catch. If a cover
opens during operation, a system shutdown will occur.