Enardo gauge hatches are widely used in steel and fiberglass low pressure tanks. When the overpressure in the storage tank rises, the flap on the breather valve begins to open at a predetermined pressure, relieving the overpressure. When the excess pressure drops, the cover is installed on the base. Hanging up the excess vacuum in the storage tank lifts the spring plate, breaking the seal between the support base and the plate. The vacuum valve is re-sealed after discharge.