Hazardous malfunction

Hazardous malfunction - if a piece of equipment was to fail in its function (that is, fail to do what it is supposed to do) and, as a result of this failure have the potential to cause harm, then this would be defined as a hazardous malfunction. 

Hazardous malfunction If a piece of equipment was to faii in its function, that is faii to... 

For example, in rotary vacuum dryers it is possible to prevent the formation of explosible dust-air mixtures by setting and monitoring a certain partial vacuum (negative pressure). This pressure value must be determined by experiment for each type of dust. With pressures of less than O.I bar, in general, hazardous effects of dust explosions need not be anticipated. If the vacuum system malfunctions, the partial vacuum must be released by inert gas and the instaUation shut down. 

Eail-Safe Design features which provide for the maintenance of safe operating conditions in the event of a malfunction of control devices or an interruption of an energy source (e.g., direction of failure of a control valve on loss of signal). A system is fail-safe if failure of a component, signal, or utility that would create a hazard initiates an action that maintains the system in a safe condition. 

Critical Equipment Equipment, instrumentation, controls, or systems whose malfunction or failure would likely result in a catastrophic release of highly hazardous chemicals, or whose proper operation is required to mitigate the consequences of such release. (Examples are most safety systems, such as area LEL monitors, fire protection systems such as deluge or underground systems, and key operational equipment usually handling high pressures or large volumes.)... 

Most operators require automatic blowdown valves so that if the compressor shuts down due to a malfunction, the trapped gas will not become a potential hazard. On some small onshore compressors some operators prefer manual valves to make it easier to restart the compressor. The compressor is only blown down for maintenance. 

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. 

Equipment/instrumentation malfunction tliat can be a factor in tlie appearance of a hazard... 

Moisture. The effect of moisture on expls, propints and pyrots can be deleterious in terms of reliability, efficiency and safety. This unwanted ingrenlent can add uncertainty and possible hazard in the manuf, storage and eventual use of ammo. Moisture adds to the costs of ammo in many ways. These include less effective material being available per unit volume, with concomitant increases in malfunction rate, curtailed shelf life because of structural failures occasioned by moisture-generated chem reaction products and the cost of many investigations undertaken to understand and prevent effects (Expls Refs 6,8, 11, 12, 15,17,21,26, 28,31,34,35,39, 40,. 41, 43, 44, 46, 48, 52 54 Propints Refs 9, 13, 16, 19, 21, 23, 27, 29, 37 53 Pyrots Refs 5, 7,10, 14,18, 20, 23, 24, 28, 30 38)... 

A factual statement explaining the reasons for the FSCA, including description of the device deficiency or malfunction, clarification of the potential hazard associated with the continued use of the device and the associated risk to the patient, user or other person. 

A part of the test plan must include testing for the consequences of equipment malfunction, deviations in process conditions, and human error. Bench-scale equipment, for example, the RC1, is quite suitable for such experiments. By analysis of the process, critical conditions can be defined, which then need to be tested in order to be able to proceed safely from the laboratory to pilot plant studies. In testing abnormal conditions or process deviations, caution is required to assure that no uncontrollable hazard is created in the laboratory. Typical deviations, including impact on the process, are discussed in the following paragraph. 

Examples of these re-occurring Tow consequences deviations are minor damage of non-critical safety equipment, operator complaints, maintenance problems, quality problems, etc. Examples of high consequences deviations (that are covered by the current pro-active Sis) are small leakages of hazardous substance, damages to or the malfunctioning of safety critical equipment, violation of safety guidelines and procedures, etc. 

The throughput for a given equipment size is far superior in continuous reactors, but problems with transients and maintaining quaHly in continuous equipment mandate serious analysis of reactors to prevent expensive malfunctions. Large equipment also creates hazards that backyard processes do not have to contend with. 

A common deaerator malfunction. Big Jim was once a high-school teacher in New Orleans. I do not quite understand the connection, but many high-school teachers become really good process plant operators. Perhaps they find the work less hazardous. Big Jim became an operator at the utility complex for a major New Orleans area sugar refinery. Here is a rather neat problem that Jim and I solved together. 

Relief valves are preferred for use on clean materials, because automatic closure prevents excessive discharge once excessive pressure is relieved. Rupture disks are less susceptible to plugging or other malfunctions but may allow complete emptying of the vessel, thus creating a safety or environmental hazard. Where fluctuating pressures or very corrosive conditions exist, or where polymerizable materials could prevent proper operation of a relief valve, some designers install two safety devices in series, ie, either two rupture disks or an upstream rupture disk followed by a relief valve. With either arrangement, it is imperative that the space between the two relief devices be monitored so that perforation or failure of the relief device closest to the vessel may be detected (86). 

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