Question 1138 Deck General

The correct answer is B) Pressure-vacuum. Acrylonitrile is a flammable and toxic chemical that requires a closed vent system to prevent the release of vapors. Pressure-vacuum vents are commonly used on barges and tanks carrying hazardous chemicals like acrylonitrile to allow for the controlled release of vapors during changes in pressure, while preventing the unintended release of vapors. Open vents (option A) would not provide the necessary containment for a hazardous chemical. Rupture disks (option C) and safety relief valves (option D) are designed for emergency pressure relief, not for normal venting operations.