.-(1) No person shall load or unload any tank vehicle unless he has selected the correct filling hose and otherwise satisfied himself that such loading or unloading will not result in any dangerous contamination of one class of petroleum with another class of petroleum.(2)A tank or compartment which carried petroleum Class A shall not be filled with any other class of petroleum until such tank or compartment has been completely drained of residual oil and its discharge faucet and emergency control valve have been closed firmly.
