Abstract: A thermoplastic material melting and dispensing apparatus includes a hopper, a melting grid, and a lid assembly which vents the interior of the hopper in an over pressure situation. Specifically, the lid assembly may be mounted with a spring-loaded hinge mechanism and may include a spring-loaded latch mechanism which each allow the lid to move upwardly away from a gas seal in the event that the gas pressure within the hopper exceeds a predetermined amount. The apparatus further includes a gas purging system which constantly circulates a gas, such as nitrogen, within the hopper interior. This gas purging system may include a solenoid valve which opens to allow exhaustion of pressurized gas from the hopper interior and the introduction of gas from a pressurized supply. A melting grid is provided which includes an surface with grooves communicating with a central outlet.