The use and characteristics of the tank car tank manhole covers with breathing and emergency vent functions are essential for the safe and efficient operation of oil tankers. These covers serve multiple purposes, including maintaining the internal pressure balance within the tank during normal operations and providing emergency air exhaust in the event of a sudden pressure surge.

The breathing valve is a critical component of the manhole cover system, as it allows for the release of excess pressure and the intake of air to maintain the desired pressure balance within the tank. This is important to prevent the tank from becoming overpressurized, which could lead to dangerous conditions or even explosions.

In the event of a tanker accident, the respiration valves of the overflow device remain sealed, preventing the medium from leaking out of the tank. This is a crucial safety feature that helps to prevent major accidents and minimize the environmental impact of any spillage.

The manhole cover can also be equipped with additional features such as an exhaust gas recycling valve, oil hole, and spill-proof sheath material. These additional features enhance the functionality and safety of the system, allowing for the efficient and safe handling of oil and other fluids.

Overall, the tank car tank manhole covers with breathing and emergency vent functions are an essential component of any oil tanker's safety and operational systems. They provide a reliable and effective means of maintaining pressure balance within the tank, preventing accidents, and minimizing the environmental impact of any spillage.