Automatic Door Bottom With Intumescent Extended Drop

An automatic door bottom comprising:

• an inverted U-shaped channel with an upper internal section disposed along a closed end of the channel and a lower internal section disposed along an open end of the channel;
• a drop bar assembly including a flexible sealing element slidably disposed within the inverted U-shaped channel;
• and
• an intumescent material communicating with the upper internal section of the inverted U-shaped channel and with an upper portion of the drop bar assembly;
• wherein the intumescent material is configured, when exposed to heat or temperature above a predetermined threshold, to forcefully expand within the upper internal section of the inverted U-shaped channel to push the drop bar assembly slidably within the channel, where at least the sealing element extends from the open end of the channel and seals the drop bar assembly against a sill beneath a door to which the automatic door bottom is configured to be attached.

An automatic door bottom comprising:

• an inverted U-shaped channel having facing longitudinal rib members formed internally thereof dividing the channel into upper and lower internal sections, with the upper internal section disposed along a closed end of the channel and the lower internal section disposed along an open end of the channel;
• a drop bar assembly including a flexible sealing element slidably disposed within the lower internal section;
• a pushrod assembly including at least one spring mechanism, the pushrod assembly mounted within the upper internal section of the channel and configured to control slidable movement of the drop bar assembly, and
• an intumescent material communicating at least with an upper portion of the lower internal section of the channel and with an upper portion of the drop bar assembly;
• wherein the pushrod assembly is activated by a plunger extending from the upper internal section of the channel, wherein the plunger is configured to be compressed into the upper internal section of the channel upon door closing against a door frame, the compressing plunger configured to activate the at least one spring mechanism to push the drop bar assembly slidably within the channel, where at least the sealing element extends from the open end of the channel and seals against a sill beneath a door to which the automatic door bottom is attached;
• and
• wherein the intumescent material is configured, when exposed to heat or temperature above a predetermined threshold, to forcefully expand within at least the upper portion of the lower internal section of the channel and to push the drop bar assembly slidably within the channel, where at least the sealing element extends from the open end of the channel and seals the drop bar assembly against a sill beneath a door to which the automatic door bottom is configured to be attached.