PLANT DESIGN

General Design Considerations Health Safety Loss Prevention Environmental Considerations

General Design Considerations Plant Location Plant Layout Plant Operation and Control Utility use Structural Design Materials Handling Storage and patent considerations

Health and Safety Hazards Inherent Toxicity of Material Frequency and Duration of Exposure Safety Hazard Industrial Health and Hygiene Hazard Permissible Exposure Limit (PEL) Threshold Limit Value (TLV)

Sources of Exposure The main objective of health hazard control is to limit the chemical dosage of a chemical by minimizing or preventing exposure. Sources of Contaminants must be controlled. Mechanical abrasions of solid materials by cutting, grinding, or drilling can produce small particles that can form an airborne dust cloud or solid aerosol. Liquid aerosols may be produced by any process. Contaminant vapors are normally formed by allowing the liquid to evaporate into the air. Pumps and valves are probably the major source.

Sources of Exposure Flammable materials Fugitive Emissions Solids handling can provide considerable exposure to contaminants whenever the operation is performed in an open atmosphere. Maintenance of any closed system can pose a hazardous exposure problem. Spilled materials can become airborne and pose an inhalation hazard.

Exposure Evaluation If health hazards are to be controlled, they must be recognized and evaluated. A logical place to initiate the process of health hazard recognition is with a total inventory of all materials present in the various stages of the process. An estimate of the toxicity or intrinsic hazard is required by the OSHA Hazard Communication Standard in the form of a Material Safety Data Sheet (MSDS).

Control of Exposure Hazards There are three general control principles utilized in reducing the exposure of workers to occupational health hazards. These involve source controls, transmission barriers and personal protection. Personal protection against exposure by inhalation can be accomplished by respirators.

Fire and Explosion Hazards For a fire to occur, there must be a fuel, an oxidizer and an ignition source. The minimum concentration of fuel in air required for ignition at ambient temperature is known as the Lower Flammable Limit (LFL). The concentration above which ignition will not occur is labeled the Upper Flammable Limit (UFL). The concentration of oxidizer that must be present for ignition is called the Limiting Oxygen Index (LOI).

Fire and Explosion Hazards The temperature at which ignition will occur without the presence of a spark or flame is designated the Autoignition Temperature (AIT). The liquid temperature at which the concentration of the fuel in the air becomes large enough to ignite is labeled the Flash Point.