Final answer:
Never heat a recovery tank with an open flame because it can be extremely dangerous.
Step-by-step explanation:
Never heat a recovery tank with an open flame because it can be extremely dangerous. Open flames can ignite flammable substances or gases present in the tank, leading to explosions or fires. This is especially true when working with volatile chemicals or substances that have low flash points. It is important to follow safety guidelines and use appropriate heating methods when handling recovery tanks.