The airtight manhole cover has a good sealing effect and has a built-in sealing ring. It is one of the commonly used manhole cover choices in communications, power, and other industries. Common ones are rectangle, circle, or square. The air-tight manhole cover is better fixed, not easy to loosen, and not easy to crush. An inner manhole cover can be set under the manhole cover to prevent personnel from falling into the "double insurance". The airplane door design is adopted, the inner edge of the frame has a certain slope, the outer edge of the manhole cover is parallel to it, and the manhole cover is covered, directly embedded, and will not move randomly, and sufficient clearance is reserved for the rubber ring to seal impermeable. The built-in sealing strip is made of rubber, which not only has airtightness but also reduces the noise when the car passing. Read More