What does the screen fitted on cargo tank vents primarily prevent?

The screen fitted on cargo tank vents is primarily designed to prevent flames and other hazards from entering the tank vent. This feature is crucial because it enhances safety by preventing fire from reaching the tank, which could lead to catastrophic events such as explosions or the ignition of flammable vapors present within the tank. This is particularly vital for tankers carrying volatile substances, where even a small flame could pose a serious threat to the vessel and crew.

While other safety measures on tankers address issues like preventing debris from entering or managing pressure, the specific role of the vent screen is to act as a barrier against flames and external fire hazards. This is an essential aspect of the overall safety protocol on tankers and is part of a larger system of fire safety procedures aimed at protecting the ship's cargo and crew from fire-related incidents.