A gas collector for collecting gasses from within a reaction chamber of a reactor comprises a body having a conduit, at least one inlet, an outlet, and a seal disposed on the body. The seal cooperates with a lid of the reactor to prevent escape of reaction gasses from the reaction chamber. The body includes first and second members and is formed from graphite. The seal is formed from molybdenum and is ring-shaped with a generally crescent-shaped cross-section and inner and outer edges. A top surface of the body includes a pair of concentric slots into which the inner and outer edges are respectively positioned. The first and second members can be detachably connected to one another, and the first and second members can be stationary relative to one another during operation of the gas collector.