CDL Hazardous Materials Endorsement (HME)Bulk Tanks and Other ContainersMedium
A cargo tank motor vehicle is transporting a liquid hazardous material. The tank is equipped with an internal self-closing stop valve. Federal regulations require a shear section to be incorporated into the valve design. What is the primary purpose of this shear section?
- ATo ensure the valve remains closed in the event of damage to external piping.
- BTo facilitate faster unloading of the hazardous material.
- CTo allow for manual override of the automatic closure system.
- DTo prevent accidental opening of the valve during transit.
Show answer & explanationAnswer & explanation
Correct answer: A. To ensure the valve remains closed in the event of damage to external piping.
The shear section is designed to break at a predetermined point when external piping is severely damaged or torn away in an accident. This ensures that the internal valve remains closed, preventing a catastrophic release of the hazardous material from the tank.
Why the other options are wrong
- B. The shear section is a safety feature, not related to the speed of unloading.
- C. Manual override is a separate function, not the purpose of a shear section.
- D. Preventing accidental opening is a general design goal for valves, but not the specific purpose of the shear section.
Internal Valve Shear Section
A shear section in a cargo tank's internal stop valve is a weakened point designed to break cleanly upon impact or stress to external piping, ensuring the valve remains closed and prevents product release.
- Protects against external piping damage.
- Ensures valve integrity in accidents.
- A crucial safety feature for liquid hazmat.
Memory trick: Shear it off to keep the valve sealed tight.