FC-40: Appearance: Brown Liquid Severe (Be): 44 Ferric Chloride %: Greater than 40% Fe2+ %: Less than 0.3% Free Acid % Less than 0.3% FC-37: Appearance: Brown Liquid Severe (Be): 40 Ferric Chloride %: Greater than 37% Fe2+ %: Less than 0.3% Free Acid % Less than 0.3%. PE drum.