A passive explosion isolation valve (10) is provided that comprises vertically-oriented gate members (40, 42) configured to close automatically in response to an energetic event occurring downstream of the valve. The valve (10) may be optionally equipped with a valve seat cleaning assembly (46) configured to removed accumulated particulate material away from the area of the valve seat (48) and/or one or more latch assemblies (44) configured to secure the gate members (40, 42) in the closed position following closure of the valve (10) in response to an energetic event.