Offloading using air

When using air to offload tank cars, NorFalco strongly recommends the use of a remotely activated shut-off valve installed between the tank car and the sulfuric acid hose. Should there be a leak or failure in the hose or downstream piping, this valve will be critical in stopping acid flow quickly. Without such a valve, it can take many minutes to depressurize a tank car and eventually stop the flow of acid. 

Air pressure should be applied slowly to the tank car or truck to establish a flow of acid to the storage tank. Check the pressure gauge to ensure that it does not exceed 30 psi. The flexible acid line must be supported because of the high specific gravity of sulfuric acid. 

If any leaks develop in the acid lines, the air must be shut off and the air pressure released from the tank before attempting to correct the leaks. 

A drop in air pressure and the sound of air rushing through the discharge line indicates that the tank car or truck is empty. Sufficient air should be blown through the line to free it of all product.

The air supply should be shut off and the pressure released by opening the release valve. When the tank is at atmospheric pressure, the air line can be disconnected from the tank.