CDL Hazardous Materials Endorsement (HME)Bulk Tanks and Other ContainersMedium
A cargo tank motor vehicle is transporting a hazardous material that is a liquid. The tank is equipped with various valves and fittings. Which of the following is typically a required safety feature for cargo tanks carrying liquids that helps prevent accidental discharge in case of valve failure or external damage?
- AManhole covers.
- BEmergency internal self-closing stop valves.
- CExternal shut-off valves.
- DPressure relief vents.
Show answer & explanationAnswer & explanation
Correct answer: B. Emergency internal self-closing stop valves.
Emergency internal self-closing stop valves are crucial safety features for cargo tanks carrying liquids. They are designed to close automatically in case of an emergency, such as valve failure or impact, preventing the uncontrolled release of the hazardous material. These are often operated remotely.
Why the other options are wrong
- A. Manhole covers provide access and seal the top, but are not primarily for preventing discharge from bottom outlets.
- C. External shut-off valves are common, but internal valves provide an additional layer of protection closest to the tank shell.
- D. Pressure relief vents prevent over-pressurization, but not necessarily accidental discharge from a damaged valve.
Cargo Tank Internal Stop Valves
Emergency internal self-closing stop valves are safety devices located inside a cargo tank, designed to automatically close and prevent hazardous liquid discharge in case of external valve damage or other emergencies.
- Located inside the tank shell.
- Self-closing mechanism.
- Often remotely operated.
- Critical for preventing spills during accidents.
Memory trick: For a liquid tank, the 'Internal Valve' is like a hidden bodyguard, stopping leaks from the inside out.