Safe Systems

ISA RP 12.6. 1987. Installation of Intrinsically Safe Systems for Hazardous (Classified) Locations. (ANSI approved.) Instrument Society of America, Research Triangle Park, N.C. 

Safe systems of work to control plant modifications etc... 

Company management systems and safe systems of work . 

Requirements for work m confined spaces, including avoidance of entry if reasonably practicable, provision of a safe system of work and establishment of adequate emergency aiTangements. 

Analy zing Nuclear Reactor Safely Systems... 

The mere fact that voltage, current, or even both, are at low levels does not guarantee a circuit to be intrinsically safe, even though intrinsically safe circuits do utilize relatively low voltage and current levels. Intrinsically safe systems employ electrical barriers to assure that the system remains intrinsically safe. The barriers limit the voltage and current combinations so as not to present an ignition hazard should a malfunction develop. Typically, devices upstream of barriers are not intrinsically safe and are installed in control rooms or other unclassified locations. All devices and wiring on the downstream side of the barriers are intrinsically safe and can be installed in classified areas. 

An additional benefit of intrinsically safe systems is the reduction of electrical shock hazards. It is cautioned, however, that intrinsically safe systems are not necessarily tested specifically for personnel shock hazards. 

Circuit capacitance and inductance, including the values of these parameters for interconnecting wiring, are integral parts of the overall analysis. It is not always possible to assure that the system will be maintained as designed with only approved intrinsically safe components and with circuits of the capacitance and inductance as originally installed. For this reason, intrinsically safe systems are used primarily at locations where there are sufficiently trained personnel to assure that the intrinsic safety of the system is always maintained. 

Safely Systems Fire-Fighting Systems Fire Water Pumps... 

An Aging Failure Survey of LWR Safely Systems and Components Nuclear 4 Tables of component failures per years of service Light Water Reactor Safety System Components 93. 

Optical fiber cables and fiber optic devices approved as an intrinsically safe system suitable for the hazardous (classified) location involved shall be installed in accordance with Sections 504-20 and 770-52. 

Intrinsically Safe Systems. Intrinsically safe apparatus and wiring shall be permitted in any hazardous (classified) location for which it is approved, and the same provisions of Articles 501 through 503, 505, and 510 through 516 shall not be considered applicable to such installations, except as required by Article 504. 

FPN No. 3) ft is not good practice to install electrical equipment in Zone 0 locations except when the equipment is essential to the process or when other locations are not feasible. (See Section 500-2.) If it is necessary to install electrical systems in Zone 0 locations, it is good practice to install intrinsically safe systems as described by Article 504. 

Are there safe systems of work implemented during the operation and maintenance of the plant and equipment (This may necessitate a permit to work to be issued by an authorized competent person.)... 

Working alone presents a specific health and safety problem, and companies, department managers and contractors must ensure that there is a safe system whereby ... 

Comply with any Method Statement or safe system introduced for his or her health and safety ... 

SAFE SYSTEM OF WORK A formal procedure resulting from systematic examination of a task to identify all the hazards. Defines safe methods to ensure that hazards are eliminated or risks controlled. 

The filling method (See Figure 2) is essentially a fail-safe system in that controls are designed to prevent double-cycling. The filling valve and the reservoir valve are electrically interlocked so... 

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