The term oil as used in this publication includes only those crude oils and petroleum products that exist as liquids at ordinary ambient temperatures. Spills ofliquefted gas such as LPG and LNG can result in the formation of extensive flammable vapor clouds but since they cannot exist as floating layers of liquid at ordinary ambient temperature@ they are not covered in this publication. Oil spills present pollution control problems and some oils may emit toxic vapors but this is also outside the scope of this publication.