Safety Engineering IE 4462
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This 7 page Class Notes was uploaded by Elbert O'Kon II on Tuesday October 13, 2015. The Class Notes belongs to IE 4462 at Louisiana State University taught by F. Aghazadeh in Fall. Since its upload, it has received 20 views. For similar materials see /class/222851/ie-4462-louisiana-state-university in Industrial Engineering at Louisiana State University.
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Date Created: 10/13/15
SAFETY FINAL EXAM STUDY GUIDE Pressure Hazards 1 Levels of pressure The American Gas Association indicates a high pressure line is one which operates at a pressure of more than 2 psi The ASME rates only those boilers which operate at more than 15 psi as high pressure boilers OSHA standards state High pressure cylinders mean those marked with service pressure of 900 psi or more The military have categorized above atmosphere pressures as 0 Low pressure l atmosphere to 500 psia 0 Medium pressure 500 to 3000 psia 0 High pressure 2000 to 10000 psia o Ultrahigh pressure above 10000 psia O 2 Pressure Vessel Rupture When the expansive force of a uid inside a container exceeds the container s strength it will fail by rupture A shock wave produced by rupture can produce blast effects similar to those generated by detonations 3 Water Hammer and Whipping Hose Water hammer is caused by a sudden stoppage of liquid ow so that a shock effect occurs which can cause the rupture of a line If the ow is terminated abruptly by closing a valve at the downstream end of a line the momentum of the liquid is transformed into a shock wave A whipping hose occurs when hoses with high pressure are not secured means of securing them are with sand bags chains clamps or a combination Whipping of exible hoses can generate injury and damage 4 Negative Pressure Unintended vacuums can be extremely damaging because structures may not be able to withstand reversed stresses Much of the damage done by high winds during hurricanes and tornadoes is due to negative pressures Condensation of vapors is another source of vacuum pressure which could cause collapse of closed containers 5 Protection from rupture Boilers are equipped with safety valves which permits pressures to be relieved when they exceed set values Types of safety valves include spring loaded weight lever solenoid and pilot 6 Dysbarism Dysbarism is the physical disturbances in the body caused by variations in pressure It has two basic causes release from solution of gas in the blood and expansion of free gas in the body cavities Decompression sickness is a general term that included bends caisson disease and aeroembolism Free gas within the body cavities may cause pain and injury to persons subjected to rapid pressure changes One of the most common symptoms is the stuffed feeling or pain in the ears caused by blockage of the Eustachian tube The only remedy is to subject the vich to high air pressure 7 Nitrogen Narcosis Narcosis while diving also known as nitrogen narcosis inert gas narcosis raptures of the deep Martini effect is a reversible alteration in consciousness that occurs while scuba diving at depth 8 Safety vs Relief Valve Safety valves are most commonly used as a pressure relieving device for gas or vapor while relief valves are mainly used for liquid Safety valves are frequently called pop valves because they pop fully open when a preset pressure is exceeded Relief valves do not pop open when a preset pressure is exceeded but open slightly and then open further as the pressure increases 9 Injuries The 1 cause of injury associated with pressure vessels is actually crush toes and back pains from actually handling the containers Electrical Hazards 1 Shock Although potential difference determines whether the resistance will be overcome the damaging factor and the chief source of injury and death in electrical shock is current ow The frequency and duration of the current is also a factor currents with a frequency between 20 and 100 Hz are the most dangerous Effects by various ows of 60 hertz AC current At 5 MAtremor of hand and spasm of forearm occurs At 15 MA contraction of exor muscles occurs At 50 MA ventricular brillation could occur At 200 MA the heart is likely to stop severe burning would occur 2 Causes of Shock 1 Contact with a normally bare energized conductor 2 Contact with an energized conductor on which the insulation has deteriorated 3 Equipment failure which causes an open or short circuit 4 Static electricity discharge 5 Lightning Strike 3 Static Electricity The number of ways static electricity can be generated keeps increasing because new materials are being created and put into use When you turn on the TV and you see the hairs on your hand standing up you were affected by static electricity Some ways to control the static electricity problem include selection of suitable materials making a material suitable bonding and grounding electrostatic neutralizers and humidi cation 4 GFI Ground fault interrupters are designed to protect from electrical shock by interrupting a household circuit when there is a difference in the currents in the quothotquot and neutral wires Such a difference indicates that an abnormal diversion of current from the quothotquot wire is occurring Fire and Fire Suppression 1 Types of Fire Accidental res can be divided into classes 0 Class A involve the burning of solids that produce glowing embers 0 Class B involve the burning of gases and liquid that must be vaporized for combustion to occur 0 Class C Class A or B res that also involve electrical equipment or materials near electrically powered equipment Class D Fire involving magnesium titanium zirconium or other easily oxidized metals Special categories res involving extremely active oxidizers or res involving solid missile propellants 2 Three Requirements for Fire Afuel and oxidizer and a source of ignition are required to start re Types of fuels include solvents for cleaning agents lubricants paint industrial process chemicals refrigerants insecticides plastics and paper Oxygen in the air is the most common oxidizer uorine is the only element that is a stronger oxidizer than oxygen 3 Common Explosive Materials Cotton charcoal popcorn coffee ower sawdust 4 Spontaneous Combustion Large stockpiles of garbage or other ammable material must be guarded against spontaneous heating and igni on Some solids that heat and ignite spontaneously are cotton wood shavings hay unsaturated oils and fats 5 Effects of Heat The National Fire Protection Agency indicates that the majority of the fatalities from res is caused by suffocation or inhalation of smoke and not burns A re in a closed structure produces carbon monoxide and depletes the air present For heat the human body sweats and heartbeat accelerates blood goes to ex emities For cold the human body produces goose bumps and shivers and heartbeat slows blood moves away from extremities 6 Fire Extinguishants Fire can be ex nguished by a number of different means Water is the most common means to stop a re Cooling combustibles make the area to cool for the re to continue Reac on inhibitors such as halogenated hydrocarbons break a chain reaction necessary for the re to continue Foams suppress res by cooling and blanke ng them 7 Gas Masks Gas masks cannot be used during a re in the absence of oxygen 8 Flash Point The ash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air Measuring a ash point requires an igni on source At the ash point the vapor may cease to burn when the source of igni on is removed 9 PASS Pull Aim Squeeze Sweep Explosives 1 De agration Consists of a rapid reaction during which heat is transferred from a reacting material to another nearby whose temperature is then raised to a point at which it too reacts A large mass which burns without con nement will generally create a reball whose size depends on the volume of the ammable mixture present a low magnitude shock or POOF is emitted 2 Detonations Detonation is when the velocity of reaction through the reac ng material reaches sonic or supersonic speed A highly heated ammable gas mixture may detonate after igni on The presence of a strong oxidizer can cause a reac on so fast that it is actually a detonation An increase in pressure may cause the reaction rate to increase A catalyst will cause a reaction to proceed faster by reducing the energy required for a reaction to begin The presence of a catalyst facilitates the reaction to reach detonation speeds 3 Fallout The leading cause of injury related to explosions is fallout from nuclear radia on Hazards of Toxic Materials 1 How they enter the body Toxic injury can occur at the rst point of contact between the toxicant and the body It can also occur in later systemic injuries to various organs deep in the body Systemic injuries occur most rapidly through routes that permit easiest access to the bloodstream such as the respiratory system skin and gastrointes nal tract The quickest route is by direct injection into the tissues and bloodstream uncommon in industrial accidents Absorption through an open cut or wound is common Food or the hydrochloric acid in the stomach may change and detoxify chemical compounds and make them harmless or conversely more damaging 2 Toxic Materials A material can be considered toxic or poisonous when a small quan ty will cause an injurious effect in the body of the average normal adult human Almost all materials are injurious to living organisms to some extent 3 Hypoxia Hypoxia is the oxygen de ciency that results from any interference with oxygena on of the blood or the ability of ssues to absorb oxygen The main effect of hypoxia is a decrease in mental capabilities The brain is most sensi ve to a lack of oxygen Consciousness may be lost after only a few seconds of cerebral hypoxia 0 Hypoxic hypoxia caused by low oxygen tension in the blood high al tude o Hypemic hypoxia the disturbance of the ability for the blood to carry oxygen to the tissues two of the most common causes being hemorrhage and anemia Stagnant hypoxia Due to inadequate circulation of the blood and consequently of oxygen through the body Can be caused by dehydration or by constricted vessels 0 Histotoxic hypoxia a disturbance of the tissues ability to absorb and use oxygen carried to them by the blood 4 Asphyxiants Asphyxia actually means hypoxia with the presence of high carbon dioxide in the blood and alveoli Asphyxiants can be either chemical or simple Causes of suffocation include carbon dioxide nitrogen methane and hydrogen 5 Systemic Poisoning Systemic poisons cause injury after they have been carried to the tissues of the body especially into speci c organs Systemic poisons can be divided into four categories those that Cause injury to visceral organs such as kidneys or liver Inj ure bone marrow spleen and blood forming system Affect nervous system 0 O O o Toxic metals and nonmetals cause respiratory damage a Measurement of Toxicity o LCtD ID and so on One method expresses toxicity hazard as the product of the vapor concentra on and exposure me that will produce a given response in a speci c percentage of normal subjects MLD minimum lethal dosage I Threshold Limit Values and PEIs TLV primarily for toxic agents that enter the body through the respiratory system Indicates the average concentration of toxic agent that can be tolerated during exposure for a 40 hour week continuously in a normal working lifetimePEIs9permissible exposure limits set by OSHA Emergency Exposure Limit Indicates the approximate length of time a person might remain without ill effect in an atmosphere contaminated with speci c concentrations of toxic gas 7 Nitric acid affects nerves 8 Air Cleaners Air puri ers protect only against dust mist fumes or smoke lters are made of a brous material through which the material must pass An oxygen breathing apparatus uses a portable supply of air or oxygen to satisfy the respiratory requirements of the user it makes the user independent of conditions of the ambient atmosphere Air line breathing equipment supplies air to the wearer through a connecting line from a xed source it is best to use in situations where the wearer must stay in a very limited space for a long time Electromagnetic respirators are the best Environments 1 OSHA vs EPA OSHA is responsible for ensuring the safety of the environment in any industrial plant The Environmental Protection Agency EPA is the one responsible for problems beyond the limits of any industrial plant Industrial accidents affecting the environment cause public anxiety about nuclear chemical and other plants thought to impose dangerous threats to the environment 2 Thermal Inversion Thermal inversion occurs when a layer of warm air settles over a layer of cooler air that lies near the ground The warm air holds down the cool air and prevents pollutants from rising and scattering Local temperatures rise because of the heat emitted by an industrial plant Con ned Space Entry 1 PermitRequired Con ned Space 1 It contains a hazardous atmosphere or chemicals sludge or sewage 2 It contains a material that has the potential for engul ng an entrant 3 It has an internal con guration or shape that could trap an entrant or contribute to the asphyxiation of an entrant 4 it contains any other recognized safety or health hazard 2 Classes of Con ned Spaces CLASS A con ned spaces are immediately dangerous to life CLASS B con ned spaces are dangerous but not life threatening and CLASS C con ned spaces contain a potential hazard 3 Examples A con ned space I Is large enough to enable an employee to enter and perform assigned work I Has limited or restricted means for entry and exit I Is not designed for continuous employee occupancy Include tanks vessels silos storage bins hoppers vaults and pits Radiation 1 Dr Roentgen inventor of the x ray 2 Rem Rad and Roentgen a Roentgen is a unit of measure of a material s absorption of gamma or x ray radiation Rad Roentgen absorbed dose is the amount of ionizing radiation which will result in the absorption of 100 ergs per gram of tissue Rem Roentgen equivalent man is the quantity of radiation which produces a physiological effect equivalent to that produced by the absorption of one roentgen of gamma or x ray radiation 3 Ionizing vs Non ionizing radiation Ionizing radiation includes alpha beta neutral particles X rays and gamma rays Each of these may cause injury by producing ionization of cellular components leading to functional changes in the tissues of the body Nonionizing radiations include ultraviolet light infrared and microwave 4 Eyes Eyes are the part of the body most susceptible to radiation Example people in Tibet often develop cataracts because the high altitude leaves them exposed to large doses of ultraviolet radiation 5 Disposal The best places to dispose of radioactive material are in salt mines the bottom of the ocean and deep space 6 Hot water heater A household water heater should not exceed a temperature of 140 degrees Fahrenheit 7 HalfLife Radiation never goes to zero it is eternal 8 REM The body should not be exposed to more than 5 Rem in one year Vibration and Noise 1 Noise Levels 90 Db is tolerable for 8 hrs 95 Db for 4 hrs 100 Db for 2 hours 2 Effects of Noise hearing loss digestive dysfunction loss of sleep gland dysfunction 3 Annoyance Noise with a message words is more disturbing Noise does not have to be loud to annoy people
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