Control accidental activation

To facilitate the selection of the correct control actions and minimize accidental activation of controls... 

The nonelectric firing system is simple and requires a minimum of equipment. Once initiated, however, it passes from the control of the operator. The electric system can be retained in the control of the operator up to the actual firing. Electric caps also are more waterproof. On the other hand,-the electric system is more complicated, employs more equipment, and may require the operator to remain near the scene at the time of firing. In addition, electric systems can be accidentally activated by static electricity and are hazardous to use in some target situations. 

A safety management system is defined as ongoing activities and efforts directed to control accidental losses by monitoring critical safety elements on an ongoing basis. The monitoring includes the promotion, improvement, and auditing of the critical elements regularly. 

The purpose of a safety management system is to assist management in developing and operating a system to prevent and control accidental loss, get managers and employees involved in safety activities, and increase the effectiveness of operations within the organization. A system also defines safety authorities, responsibilities, and accountabilities and sets standards for various aspects of safety, health, and environmental protection. 

The force required to move a control affects the response time, errors, accidental activation, and operator fatigue. There are different methods for introducing reactive force into a control. Methods include use of springs, friction, viscous damping, and inertia. If forces are too low, an operator may not sense the movement and may increase errors. If forces are too high, they can reduce response times and may cause fatigue in muscles used to operate a control. That may lead to fatigue errors. 

Accidental activation of some controls can lead to serious consequences. There are several methods for protecting controls from accidental activation include recessing, location, orientation, covering, locking, operational sequences, and resistance. A desirable design may include a combination of methods. The appUcation and potential consequences of accidental activation will affect the methods selected and used. If accidental activation leaves a system in a safe condition, rigorous protective methods are not as important. If accidental activation can produce a serious accident or injury, prevention of accidental activation is critical. 

Maintenance of protection for controls is also an important consideration. A failure in a protective device may increase the likelihood of accidental activation. It must undergo repair or replacement quickly to retain the value of the protective device. Protective methods should not violate other design principles directed at minimizing errors. Figure 33-5 illustrates several of these methods. 

Coding Coding methods for controls attempt to reduce and eUminate identification errors. Coding may help prevent accidental activation. Coding will have little effect on accidentally bumping a control or on population stereotypes... 

Figure 33-5. Examples of methods for preventing accidental activation of controls.

Orientation One can position controls so that normal movement around them will not activate them. If hand movements are lateral, vertical control movement for toggle switches will reduce accidental activation. If one can walk by and snag clothing on a control, vertical orientation may provide some protection. If falling objects can activate a control, both horizontal and vertical orientation may be ineffective protection. 

When machine operations, configuration, or size requires the operator to leave his or her control station to install tools or perform other operations, and that part of the machine could move if accidentally activated, is that element required to be separately locked or blocked out ... 

It is easy to see how the approach can be used to identify what the risk assessment team consider important controls which have or have not been considered in the design. Actions can then be placed to ensure additional measures are taken during the design process. It is also evident from this example how what is essentially a slip/lapse error (that is, accidental activation) has been (correctly) addressed largely by design details which will reduce the likelihood of the error occurring. Equally, it can be readily appreciated how such an approach will reduce the opportunity for designed-in error potential. 

To reduce the accidental spread of hazardous substances by workers from a contaminated area to a clean area, zones should be delineated on the site where different types of operations will occur, and the flow of personnel among the zones should be controlled. The establishment of work zones will help ensure that personnel are properly protected against the hazards present where they are working, that work activities and contamination are confined to the appropriate areas, and that personnel can be located and evacuated in an emergency. 

Before the first World Trade Center bombing in 1993 and the 1995 Oklahoma City bombing, emergency incidents were primarily or generally thought to be caused by natural or accidental events. Examples of natural phenomena (events) include wildfires, flash floods, earthquakes, active volcanoes, droughts, and storms. These natural events are not entirely predictable, and they cannot yet be controlled or prevented (Meyer 2004). 

There has been a gradual evolution in the types of fermentation products that have been developed for use in agriculture. This evolution has been punctuated by several major discoveries that have served to influence future work. The history begins with the accidental discovery of a new use for an antibiotic that was already playing a major role in the treatment of human diseases. There follows a deliberate search for new antibiotics unrelated to those used in humans, the detection of a new activity for what had appeared to be a useless antibiotic, and, finally, the discovery of a family of compounds that has opened up an entirely new area for the use of fermentation products in agriculture and may well play a major role in the control of both plant and animal diseases. 

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