Manholes are safety emergency ventilation devices installed on the top or side of beer equipment storage tanks, paired with mechanical breathing valves. They not only prevent accidents caused by sudden overpressure or vacuum inside the tank, but also have a safety fire retardant effect. They are safety devices for protecting storage tanks, especially suitable for arched atmospheric tanks that store materials sealed with nitrogen gas. It has the advantages of constant pressure discharge, constant pressure suction, flexible opening and closing, safe fire resistance, compact structure, good sealing performance, safety and reliability.

The manhole has already been formed with a diameter of typically 600mm. The center of the manhole is generally 750mm from the floor. Convenient for personnel to access and ventilate oil tanks during installation, cleaning, and maintenance.