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HVACR416 – DesignHVACR416 – Design
Two Types of AccidentsTwo Types of Accidents
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• Mechanical malfunction or human error• Electrical causes• Excessively high pressures• Burns and scalds• Explosions• Inhalation of toxic and non-toxic gases
• Mechanical malfunction or human error• Electrical causes• Excessively high pressures• Burns and scalds• Explosions• Inhalation of toxic and non-toxic gases
Accidents – Causes & Nature
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• Broken limbs• Thrown objects• Smashed fingers,
toes, etc.• Falls• Eye injuries and cuts
• Broken limbs• Thrown objects• Smashed fingers,
toes, etc.• Falls• Eye injuries and cuts
Injuries from Mechanical Causes
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Electrical InjuriesElectrical Injuries
• Three types of electrical hazards– Shock– Burns– Blast
• Three types of electrical hazards– Shock– Burns– Blast
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Current in milliamperes Effect on the human body
Less than 0.5 mA No sensation
2 to 10 mA Muscles contract
5 to 25 mA Painful shock, inability to let go
Over 25 mA Violent muscle contractions
50 to 100 mA Heart convulsions (ventricular fibrillation), possible death
Over 100 mA Heart paralysis, inability to breathe, burns, almost certain death
Effect of Electric ShockEffect of Electric Shock
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High Pressure InjuriesHigh Pressure Injuries
• Mechanical refrigeration uses pressures above atmospheric pressure– Must be contained– Vessels must not burst– Pressures change with temperature
• Mechanical refrigeration uses pressures above atmospheric pressure– Must be contained– Vessels must not burst– Pressures change with temperature
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Pressure Containing VesselsPressure Containing Vessels
• Designed for “normal” pressures– If overheated may “give” somewhat– When limit of elasticity is reached, will burst
• Large parts may be blown out• If bulge is noticed, relieve pressure immediately
• Designed for “normal” pressures– If overheated may “give” somewhat– When limit of elasticity is reached, will burst
• Large parts may be blown out• If bulge is noticed, relieve pressure immediately
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Burns and ScaldsBurns and Scalds
• Fire hazards include:• Fire hazards include:
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Explosion InjuriesExplosion Injuries
• Explosion and flammability are related• Confined vapor seeks more room
– Pushes outward with tremendous force• “Explosion”
• Difference in catching fire vs. exploding– Exploding includes violent force
• Explosion and flammability are related• Confined vapor seeks more room
– Pushes outward with tremendous force• “Explosion”
• Difference in catching fire vs. exploding– Exploding includes violent force
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Toxic GasesToxic Gases
• Toxic = poisonous• Refrigerants and other gases vary in toxicity
– Ammonia and sulfur dioxide are highly toxic
• Harmful effects are based on– Nature of gas– Concentration– Length of time breathed
• Toxic = poisonous• Refrigerants and other gases vary in toxicity
– Ammonia and sulfur dioxide are highly toxic
• Harmful effects are based on– Nature of gas– Concentration– Length of time breathed
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Radiation AccidentsRadiation Accidents
• Radiation types– Ionizing
• X-rays
– Non-ionizing• Alignment lasers
• Welding produces ultraviolet light– Eye and skin hazard
• Radiation types– Ionizing
• X-rays
– Non-ionizing• Alignment lasers
• Welding produces ultraviolet light– Eye and skin hazard
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Heat and Cold InjuriesHeat and Cold Injuries
• Avoid extreme heat and cold
• Obvious dangers– Heat stroke– Hypothermia– Frostbite
• Other problems– Fatigue, discomfort, etc.
• Avoid extreme heat and cold
• Obvious dangers– Heat stroke– Hypothermia– Frostbite
• Other problems– Fatigue, discomfort, etc.
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Cold Weather Danger: HypothermiaCold Weather Danger: Hypothermia
• Hypothermia– Shivering– Loss of consciousness– Decreasing pulse and breathing
• If symptoms are shown– Call emergency services– Move to warm area
• Dress in layers
• Hypothermia– Shivering– Loss of consciousness– Decreasing pulse and breathing
• If symptoms are shown– Call emergency services– Move to warm area
• Dress in layers
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Cold Weather Danger: FrostbiteCold Weather Danger: Frostbite
• Ice crystals on body tissue– Ears, nose, chin, fingers, toes
• Skin color changes– Flushed, white or grayish
yellow, then grayish blue
• Ice crystals on body tissue– Ears, nose, chin, fingers, toes
• Skin color changes– Flushed, white or grayish
yellow, then grayish blue
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Cold Weather Danger: FrostbiteCold Weather Danger: Frostbite
• Signs shown?– Move to warm area, use
warm water, call health care provider
• Prevention– Cover extremities– Move to warm area if
pain is evident
• Signs shown?– Move to warm area, use
warm water, call health care provider
• Prevention– Cover extremities– Move to warm area if
pain is evident
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Accident ReportingAccident Reporting
• All must be reported without delay• Follow these steps
– Report to supervisor immediately– Employer keeps record of accident– Current codes are reviewed– Leave the site intact
• All must be reported without delay• Follow these steps
– Report to supervisor immediately– Employer keeps record of accident– Current codes are reviewed– Leave the site intact
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