CDL Hazardous Materials Endorsement (HME)Bulk Tanks and Other ContainersMedium
A driver is transporting a bulk quantity of a hazardous material in a cargo tank. The material is a liquid with a specific gravity of 1.25. The cargo tank has a maximum allowable working pressure (MAWP) of 25 psi and a test pressure of 37.5 psi. To determine the maximum permitted weight of the hazardous material, which of the following is the most critical piece of information to consider first?
- AThe last inspection date of the cargo tank
- BThe volume of the cargo tank
- CThe specific gravity of the liquid
- DThe material of construction of the cargo tank
Show answer & explanationAnswer & explanation
Correct answer: B. The volume of the cargo tank
While specific gravity is essential for converting volume to weight, the fundamental constraint for how much material can be loaded into a tank is its physical volume. You cannot exceed the tank's volumetric capacity, regardless of the material's density.
Why the other options are wrong
- A. The last inspection date ensures the tank's safety and certification but doesn't directly limit the filling quantity for a specific load.
- C. Specific gravity is needed to calculate weight from volume, but volume is the primary limit.
- D. Material of construction affects MAWP and structural integrity, but not directly the maximum weight limit for a specific load once the tank's volume is established.
Bulk Tank Filling Limit Basis
The primary factor in determining the maximum amount of a hazardous material that can be loaded into a bulk tank is its volumetric capacity, which dictates the total space available.
- Volume is the physical constraint.
- Specific gravity converts volume to weight.
- Weight limits are often derived from volume.
Memory trick: Volume first, then density to get the weight right.