Room Hazards

The most overlooked hazard and contaminant is water (99). Water reacts with isocyanates at room temperature to yield both ureas and large quantities of carbon dioxide. The presence of water or moisture can produce a sufficient amount of CO2 to overpressurize and mpture containers. As Httle as 30 mL of water can result in 40 L of carbon dioxide which could result in pressures of up to 300 kPa (40 psi). For these reasons, the use of dry nitrogen atmospheres is recommended during handling. If a plant air system must be used, purification equipment, such as oil traps and drying beds, should be installed between the source and the isocyanate vessel. 

Nonwoven wipe categories include products for babies and adults, the food service and electronics industries, medical and clean room appHcations, industrial cleaning, computer diskettes, and household products such as dusters, tea towels, shoe cleaning cloths, towelettes, and hand towels. Nonwoven fabrics are used to filter air, water, petroleum (qv), food, and beverages. Nonwovens loaded with abrasives, cleansers, or finishes can be found in a variety of products used by many industries and in many homes to scour or poHsh. Also, a majority of garments designed to protect industrial workers and consumers from hazardous environments are made from nonwoven fabrics. 

Electrical Hazards. Because carbon fibers are conductive, the airborne filaments can create serious problems shorting out electrical equipment. The best option is to locate sensitive equipment in clean rooms outside of areas where carbon fiber is being processed. If this is not possible, electrical cabinets must be effectively sealed to prevent contact with carbon fibers. A filtered air-positive purge provides additional protection for sensitive equipment. 

Combustible Dusts Dusts are particularly hazardous they have a very high surface area-to-volume ratio. When finely divided as powders or (dusts, solids burn quite differently from the original material in the bulk. Dust and fiber deposits can spread fire across a room or along a ledge or roof beam very quickly. On the other hand, accumulations of dust can smolder slowly for long periods, giving little indication that combustion has started until the fire suddenly flares up, possibly when no one suspects a problem. 

Provide positive control room pressure to prevent inflow of hazardous material... 

Provide doors on the side of the control room opposite to expected hazard sources... 

These couplings are totally enclosed and are suitable for any environment prone to fire hazard, corrosion, dust or any other pollutants. The controls can be provided remotely in a safer room and the pushbutton stations, which can be easily made suitable for such environments, located with the drive. 

For hazardous areas flameproof enclosures alone are recommended, except in areas with moderate intensity of contamination and where such assemblies are located away from the affected area and in a separate well-ventilated room, when pressurized enclosures may also be. safe. The reason for this precaution is that frequent arcing takes place within the enclosure on each switching of a contactor, switch, breaker or an OCR etc. and also during operation of power and auxiliary contactors. 

Since it is not practical to manufacture a llameproof enclosure due to its size and bulk and the number of knockouts and openings on the doors for switches, metering, indicators, and pushbuttons (PBs) etc., it is common practice to locate the.se assemblies some distance from the affected area in a separate well-ventilated room. Depending upon the location and intensity ol contamination, it may be permissible to meet the requirement by using a pressurized enclosure by maintaining a positive pressure inside the enclosure similar to that for motors (Section 7.1.3..3). When there arc many switchgear assemblies, the room itself can be pressurized, which is safer and easier. Small enclosures, however, such as a PB station, switch or a switch fuse unit or an individual starter unit etc., which can be easily made of MS plates or cast iron, as discussed in Section 7.13, can be mounted in the hazardous area while the main MCC can be installed in the control room, away from the contaminated area and from where the process can be monitored. 

They may be rated as more fire hazardous than a BOCB or MOCB in view of arc formation taking place ill the open, although under controlled conditions. They are not suitable for installations prone to fire hazards, unless the sub-station or the control room where they are installed is isolated from the area of hazards (Section 7.1 I). They are generally suitable for all other areas... 

Enrichment of a room atmosphere >25% creates a hazardous situation enrichment in a confined space is particularly dangerous. 

Conditions - For each hazardous substance that you are reporting, provide the appropriate codes for both the "Pressure" and "Temperature" at which the substance is stored. IMPORTANT - You will be entering two co numbers for "Conditions". If a substance is stored at room temperature and normal pressure, report code for "ambient". 

All supply inlets without a specific exhaust have the same problem, the spreading of contaminants in the room outside the supply air zone. When the inlets are used to create a cleaner zone in a normal workroom this is usually no problem. When a supply inlet is used to blow away some hazardous contaminant it is necessary to combine it with a specific exhaust, or the rest of the room will be contaminated. 

It should be noted that the primary purpose of the ventilation systems described for abrasive blasting rooms and hospital isolation rooms is to prevent or minimize exposure to hazardous substances in those persons working outside the blasting or isolation room. The ventilation system may also reduce exposure for workers inside these rooms, but often the reduction is not sufficient to eliminate the need for respiratory protection. 

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. 

Interactions refers to any jobs, tasks, or operations carried out by people who could directly or indirectly cause the hazard to be released. Direct interactions with the plant might involve breaking open pipework, opening reactors, etc. Indirect interactions would include remote activation of valves from a control room, or the performance of maintenance on critical plant items. Errors that might occur during these interactions could allow the harm potential to be released. This could occur directly (for example, a worker could be overcome by a chlorine release if an incorrect valve line-up was made) or indirectly (for example, if a pump bearing in a critical cooling circuit was not lubricated, as in the example in Chapter 1). The procedure as described above... 

The human factors audit was part of a hazard analysis which was used to recommend the degree of automation required in blowdown situations. The results of the human factors audit were mainly in terms of major errors which could affect blowdown success likelihood, and causal factors such as procedures, training, control room design, team communications, and aspects of hardware equipment. The major emphasis of the study was on improving the human interaction with the blowdown system, whether manual or automatic. Two specific platform scenarios were investigated. One was a significant gas release in the molecular sieve module (MSM) on a relatively new platform, and the other a release in the separator module (SM) on an older generation platform. 

Flash point of a flammable liquid The lowest temperature at which the liquid gives off enough vapors to form a flammable mixture with air (or pure oxygen, a special case) at or near the surface of the liquid or within its confined container. Some hazardous liquids have flash points at or below ordinary room temperatures and normally are covered by a layer of flammable vapors that will ignite immediately if a source of ignition is brought in contact [32]. Flash points are measured by open cup and closed cup methods. The open cup data is applicable to liquid in open containers and in open pools and usually somewhat higher temperatures than the closed cup. Refer to... 

---