An employee was unloading a tanker full of chemicals into a storage tank. During this process, a pipe at the base of the tank broke and the chemical began running into the containment chamber. One of the employee's attempted to plug the leak with a piece of wood when the air pressure caused the material to discharge in a vaporized form. A second employee entered the area to offer their assistance. Both employees suffered irritation to their respiratory systems and eyes. One employee was hospitalized.