Component intrinsic hazards

An estimate of the toxicity or intrinsic hazard is needed for each material identified in the inventory. Such information for many chemicals in the form of a Material Safety Data Sheet (MSDS) are required by the OSHA Hazard Communication Standard. (Other countries have similar requirements.) Standard hazard-data sources may need to be consulted for those chemical compounds for which no MSDSs are presently available. Adequate hazard data may be lacking for various mixtures that are unique to the plant. For such mixtures, it may be necessary to analyze the contents and then estimate the overall hazard based on the individual components. 

ID Component in zone External failure mode(s) Intrinsic hazards Systemic vulnerabilities Effect on the aircraft Corrective/preventative action and/or mitigations... 

First, once designed, evaluated, and installed, the safety of the system cannot easily be degraded because the safety is in the design, not protection added afterward. In fact, the intrinsically safe electrical circuit will cease to fulfill the function for which it was designed long before it can become a hazard. This is due to the consideration which must be given to fault conditions. The only possible way for the circuit to become hazardous is if an unapproved or unauthorized component is substituted into the circuit. 

Intrinsic safety is based on the principal of restricting the electrical energy available in hazardous area circuits such that any sparks or hot surfaces that may occur as a result of electrical faults are too weak to cause an ignition. The useful power is about 1 watt, which is sufficient for most current instrumentation. It also provides a personnel safety factor since the voltages are low and it can allow field equipment to be maintained and calibrated "live" without the need for a gas free environment verification. Electrical components or equipment can be manufacturer as intrinsically safe and there readily usable in areas where combustible gases or vapors may be present. 

We designed an optic fiber oxygen sensor based on DEB laser wavelength scanning and spectrum absorption technique. With the use of the optical fiber links between monitor and sensor header, the system can provide remote and online monitor information. Since the sensor head is made without any active electrical components, it is intrinsically safe when used in the hazard environment such as coal mines. The oxygen sensor works in... 

Within the framework of DES, the determination of state transitions of a system from a nominal state to a hazardous state that are labeled by an unobservable event (e.g., failure of a component) constimtes the diagnosis problem. Thus, the existence of solutions to the diagnosis problem is intrinsically related to the system being diagnosable. The mathematical characterization of the concept of diagnosability, that is, necessary and sufficient conditions for the solvability of the diagnosis problem, would... 

This is the basic equation for all toxic hazards. To be acceptable, either the intrinsic toxicity must be so low that any level of ingestion can be tolerated (which is a situation that does not apply with the majority of plastics components) or, alternatively, the quantity of migrant ingested as well as its intrinsic toxicity must be known before we can carry out a calculation. The technical position within this field has been dealt with by Adcock in a paper presented to The Plastics and Rubber Institute s Conference in March 1977. ... 

For nonrepairable systems (a system composed of many subassemblies and components), the instantaneous failure rate, termed the hazard rate h t), follows a pattern that changes with time. It is usually represented by a bathtub-shaped failure curve over time, as shown in Fig. 1 [1,1a]. It begins with an initial decreasing hazard rate attributed to premature failure due to defects. This is followed by a useful life period with an almost constant hazard rate due to intrinsic failures and, finally, a wearout period where the hazard rate increases rapidly with time. 

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