Safety hatch cover apparatus

Hatch cover apparatus for a container comprising base means fixed to the container and having an opening providing access to said container;

• a pair of keeper means rigidly fixed to the base means at opposite sides of the opening, each keeper means providing lateral access for an end of a latch bar;
• a cover associated with the base means and adapted to be put in closed position to engage the base means and close the opening and to be put in opened position to open the opening;
• an elongated latch bar adapted to have its ends engage with the keeper means when the cover is in its closed position and to be disengaged from the keeper means when the cover is in its opened position;
• means on the cover for mounting the latch bar on said cover so that it is substantially immovable axially of the latch bar relative to the cover but capable of limited movement transversely relative to the cover and of rotation relative to the cover about an axis normal to the longitudinal axis of the latch bar and essentially fixed relatively to and extending transversely of the cover, said latch bar being thus rotatable between a position in which its ends are engaged with the keeper means and another position in which its ends are not so engaged;
• cam means located about and adapted to be rotated about the latch bar axis, said cam means having projecting external surface portion means that is located a maximum distance from the latch bar axis and toward the cover when the cover is in its closed position and retracted external surface portion means located a lesser distance from the latch bar axis when the cover is not in closed locked position;
• resilient biasing means supported in gastight relation by said cover and exerting a resilient biasing force inwardly on the cover when the cover is closed and the latch bar ends are engaged with the keeper means, but when pressure above a predetermined amounts exists within the container and urges said cover outwardly against the biasing force of said biasing means, said biasing means will permit at least a portion of the cover to lift from the base means and permit escape of gas from the container.

Hatch cover apparatus for a tank comprising a base member fixed to the tank with an opening for access to the tank, a latch bar, a pair of keeper members extending outwardly from the base member at opposite sides of the opening, each keeper member having a lateral cavity formed therein to receive an end of said latch bar and restrain it from outward movement, a cam affixed to the middle of the latch bar, bearings on each side of the cam to support the latch bar and permit it to rotate about its longitudinal axis, two upstanding wall portions which are integral with the cover and which have guideways formed therein to receive said bearings and permit them to move in the plane of the cover enough distance to free the ends of the latch bar from the keeper members and which also have lateral slots therein to permit such movement of the latch bar, a handle on the latch bar, a cylindrical housing integral with the cover and inward of the cam, a coil spring disposed in said housing, a piston in the housing between the cam and the spring so that when the ends of the latch bar are in the lateral cavities in the keeper members and when the cam is turned about its axis, it bears down on said piston and depressed said coil spring to keep the cover in a sealing engagement with the base means, but when a predetermined amount of pressure builds up within the tank and acts upon said cover, the cover lifts from the base member and causes said piston to depress said coil spring still further.