Manual relief gas vent

摘要

A drum lid (10) for a ventable drum has a depression (14) formed in the surface of the lid. A vent valve (16) is placed in the depression and extends through the lid. The valve has a valve outlet (44) which opens into the reservoir in the lid. During venting the reservoir is filled with water and the valve stem (42) is slowly opened. The gas escapes into the water in the reservoir in the form of bubbles. When the bubbles stop the tank is vented and the lid can be removed.