1.2 SAFETY
• It is natural for a machine to have hazardous parts/functions/flows.
• If the risk (probability) of comming in contact is high we call this danger
• Typical hazards include,
- pinch points
- crushing
- collision with moving objects
- falling from heights
- slippery surfaces
- explossion
- electric shock
- temperature/fire
- toxicity
- physical strain
• When possible it is best to eliminate hazards. If this is not possible we want to reduce the risk of access (hence danger).
• OSHA (Occupational Safety and Health Administration) regulates workplace procedures.
• Danger can be reduced by,
- signs
- safegaurds (e.g. barriers)
- policies and procedures
- worker training
- special protective equipment (e.g. earplugs)
• Typical additions to machines include,
- barrier gaurds - physical blocks to separate operators and equipment. Interlocks are used to disable the machine when the barrier is open.
- passive safety devices - for example seat belts
- active safety devices - these include
- hand pull-backs
- dead-man controls
- presence sensing devices
- maintenance safety devices - these additions (and procedures) ensure that the machine is still safe, even though the normal safety equipment is disabled.
- warnings - large warning signs, buzzers, status lights, etc. are used to promote awareness.
• Note: It is important to place safety considerations at the top of the design priorities. It is so obvious that it is quite often assumed.
1.2.1 Environment
• Environmental considerations are a natural consideration of the design process and can be considered an extension of safety.
• design factors that will impact the environment include,
- discharges/waste (gas, liquids, solids) from production processes
- energy/fuel utilization in production
- aging of the product - decay, inert, toxic, etc.
- energy/fuel efficiency in use
• There are a wide variety of laws, agencies and organizations that influence manufacturing and consumer products,
OSHA (Occupational Safety and Health Administration)
EPA (Environment Protection Agency)
NIOSH (National Institute for Occupational Safety & Health)
UL (Underwriters Laboratory)
CSA (Canadian Safety Association)
1.2.2 MIL-STD 882B - System Safety Program Requirements
• This standard addresses the likelyhood and acceptability of hazards.
• The basic tables are,