When top loading a cargo tank with vapor control, flow control shall be in accordance with ______ loading.

When top loading a cargo tank with vapor control, flow control shall be in accordance with ______ loading.

• A. Top
• B. Bottom
• C. Vapor
• D. Partial

Answer: (B)

Flow control is set to the bottom loading rate. In a top-loading operation with vapor control, the liquid enters the tank through the bottom-side flow path and is limited by the same flow-control device that governs bottom loading. The vapor recovery system handles vapors, but it does not determine how fast liquid can be introduced. By aligning the liquid flow with bottom loading criteria, the system ensures the tank fills at a safe, recoverable rate and remains within the vapor system’s capacity, preventing overpressure or vapor bypass. The vapor or partial loading approaches don’t establish the actual liquid flow limit, so they’re not the correct basis for control here.

Flow control is set to the bottom loading rate. In a top-loading operation with vapor control, the liquid enters the tank through the bottom-side flow path and is limited by the same flow-control device that governs bottom loading. The vapor recovery system handles vapors, but it does not determine how fast liquid can be introduced. By aligning the liquid flow with bottom loading criteria, the system ensures the tank fills at a safe, recoverable rate and remains within the vapor system’s capacity, preventing overpressure or vapor bypass. The vapor or partial loading approaches don’t establish the actual liquid flow limit, so they’re not the correct basis for control here.