© 2012 Delmar, Cengage Learning Chapter 5 Hazards of Liquids

© 2012 Delmar, Cengage Learning The Hazards of Liquids Physical: combustible, compressed, explosive, oxidizer, and pyrophoric. Chemical: carcinogens, mutagens, teratogens, reproductive toxins, caustic or acidic. Biological: insects, bacteria, fungi, and molds.

© 2012 Delmar, Cengage Learning Physical Hazards Associated with Liquids Combustible liquid has a flashpoint between 100°F and 200°F Flammable liquid has a flashpoint below 100°F Pyrophoric – ignites spontaneously with air at temperatures below 130°F

© 2012 Delmar, Cengage Learning Health Hazard Associated with Liquids Carcinogens – liquids that are known cancer-causing substances. Mutagen – chemical that is suspected to have the properties required to change or alter the genetic structure of a living cell. Reproductive toxin – chemical that inhibits the ability of a person to have children.

© 2012 Delmar, Cengage Learning Pressure and Pressurized Equipment The primary variables a process technician works with are: Temperature Flow Level Analytical Pressure

© 2012 Delmar, Cengage Learning Figure 5-1 Pressure Control Loop

© 2012 Delmar, Cengage Learning Figure 5-2 Process System

© 2012 Delmar, Cengage Learning Flammable Liquid Storage Metal cabinets Tanks and vessels Nitrogen blanket can be used to keep flammable liquids under pressure

© 2012 Delmar, Cengage Learning Spontaneous Combustion Spontaneous combustion is the result of a slowly developing chemical reaction that produces its own heat.

© 2012 Delmar, Cengage Learning Figure 5-4 Fire Tetrahedron and Chemical Reaction

© 2012 Delmar, Cengage Learning Hazards of Steam The most common hazards associated with steam are physical exposure to live steam, contact with heated equipment, non-uniform heat transfer, and equipment over-pressuring. High-pressure steam discharged from a small opening has enough energy to cut through solid materials.

© 2012 Delmar, Cengage Learning Hazards of Water When water flashes to steam at 100°C it expands 1,500 to 1,600 times its original volume. Uncontrolled mixing of water with hydrocarbons can generate high- pressure conditions that can damage systems.

© 2012 Delmar, Cengage Learning Foamover occurs when water vaporizes under hot, heavy oil or asphalt. The foam can expand to 20 or 30 times the original volume of the product pumped in. Water and acid do not respond well with each other. Pour acid into water; never pour water into acid.

© 2012 Delmar, Cengage Learning Figure 5-5 Uncontrolled Mixing in a Heat Exchanger

© 2012 Delmar, Cengage Learning Vacuum towers operate below atmospheric pressure which lowers the boiling point of water. The volume expansion is much greater in low- pressure situations.

© 2012 Delmar, Cengage Learning Figure 5-6 Pressure Effect

© 2012 Delmar, Cengage Learning Hazards of Light Ends Viscosity – Can easily escape from enclosed systems Frostbite – When light-ends contact human skin, heat is absorbed. Thermal expansion – Overheating must be avoided. Hazard of air – Air and light-ends mixed can lead to an explosion.

© 2012 Delmar, Cengage Learning Acids and Caustics Acids – Have a pH between 0 and 7.0 and turn litmus paper red. Caustics – Have a pH between 7.0 and 14.0 and turn litmus paper blue. Acids donate a proton to a base.

© 2012 Delmar, Cengage Learning Figure 5-7 pH Scale