Active sealing manhole cover for vapor and liquid isolation

A manhole cover assembly for sealing a manhole against emissions, wherein the manhole defines an interior surface, comprising:

• a top plate;
• a bottom plate beneath the top plate;
• a first plurality of fasteners inserted into the top plate and the bottom plate;
• a first annular cavity defined about an exterior surface of the manhole cover;
• a second annular cavity defined about the exterior surface of the manhole cover;
• a first flexible seal inserted in the first annular cavity configured to seal against the interior surface in an active state of the manhole cover assembly and configured to disengage from the interior surface in a free state of the manhole cover assembly;
• and
• a second flexible seal inserted into the second annular cavity configured to seal against the interior surface.

A method for sealing a manhole against leaking vapor and emissions, comprising the steps of

• torquing a number of bolts in a manhole cover in a first direction to install the manhole cover into the manhole, wherein the manhole cover comprises a plurality of plates stacked together and an annular cavity between each of the plurality of plates, wherein the annular cavity is defined at the exterior surface of the manhole cover, and further comprising an O-ring in the annular cavity;
• compressing the plurality of plates together and decreasing a size of the annular cavity;
• pushing the O-ring towards an interior surface of the manhole;
• and
• sealing the manhole via the O-ring.

A manhole cover for sealing a manhole, comprising

• a top plate defining a top plate angled surface around a perimeter of the top plate, wherein the top plate angled surface faces a bottom of the manhole cover;
• a bottom plate beneath the top plate, and wherein the bottom plate defines a bottom plate angled surface around a perimeter of the bottom plate, and wherein the bottom plate angled surface faces a top of the manhole cover;
• and
• a first O-ring situated between the top plate angled surface and the first middle plate angled surface.

A manhole cover for sealing a manhole having an interior surface, comprising:

• a plate defining an annular cavity about an exterior surface of the plate;
• a seal inserted into the annular cavity;
• a wedge bar below the plate, wherein the wedge bar has a base wider than a top;
• a wedge gripper configured to be slidable on a surface of the wedge bar;
• and
• a screw inserted through the plate and the wedge bar, wherein the screw is configured to compress the plate and the wedge bar together.