Hazardous environment

Today the demand for inspection of components with complex geometry, difficult access conditions or location in a hazardous environment is steadily increasing. Documentation, reproducibility and minimised health risk for the inspection staff are key issues. This leads to an increased demand for automated inspection, resulting in a need for new, advanced scarmer systems for NDE. 

BE.3038 Compact wall and ceiling climbing robotic vehicle with dexterous manipulator arm for low cost remote nondestructive insoection In hazardous environments Mr Bryan Bridge Univ. South Bank London... 

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. 

Explosion-proof enclosures are characterized by strong metal enclosures with special close-fitting access covers and breathers that contain an ignition to the inside of the enclosure. Field wiring in the hazardous environment is enclosed in a metal conduit of the mineral-insulated-cable type. All conduit and cable connections or cable terminations are threaded and explosion-proof. Conduit seals are put into the conduit or cable system at locations defined by the National Electric Code (Article 501) to prevent gas and vapor leakage and to prevent flames from passing from one part of the conduit system to the other. 

Use pneumatic/hydraulic system where necessary in hazardous environments... 

Ghosh. S.N.. Electric motors for hazardous environments , Siemens Circuit. VI. No. 4, July (1971). 

The rotor design, its cooling system or the motor size itself may have to be changed substantially for motors to be installed in fire hazard environments to limit their temperature rise in adverse operating conditions within safe limits (Table 7,6). 

In ae off-line eonverters, aluminum eleetrolytie eapaeitors are used as the input filter eapaeitor. They have proven to be more rugged than any other type of eapaeitor in the hazardous environment existing on the ae line. Choosing the final eapaeitor depends mostly upon the expeeted operating temperature range, quality level, and ease dimensions. 

Vertical Pressure Leaf Filters are essentially the same as Horizontal Plate Filters except for the orientation of the filter elements which are vertical rather than horizontal. They are applied for the polishing slurries with very lov solids content of 1-5% or for cake filtration with a solids concentration of 20-25%. As with the horizontal plate filter the vertical leaf filters are also well suited for handling flammable, toxic and corrosive materials since they are autoclaved and designed for hazardous environments when high pressure and safe operation are required. Likewise, they may be readily jacketed for applications whenever hot or cold temperatures are to be preserved.The largest leaf filters in horizontal vessels have a filtration area of 300 m and vertical vessels 100 m both designed for an operating pressure of 6 bar. 

The turbine has the features of (1) variable speed operation, (2) ease of controls, (3) nonsparking operation for hazardous environment, (4) enclosed operation suitable for corrosive atmospheres, (5) operation without electrical power, (6) small space requirements per horsepower, (7) steam use under almost any condition to suit plant heat bal-... 

According to the AMC News article authorities summed up the report by pointing out that the incident was not the direct result of normal operations, but rather was the result of an unusual condition, and that the design and operating procedures were not unsafe when considered in the context of the total hazardous environment. The process in the nitration and purification building was operating normally when the rubber hose was introduced into the system. 

Halfon Reggiani (1986) On ranking chemicals for environmental hazard. Environ. Sci. Technol. 20, 1173-1179. 

For the assessment of resistance to heat exposure and generation of hazardous environments by FRC materials, the following processes need to be examined 1) ignition, 2) fire propagation, 3) generation... 

Emergency Valves Remote Control-Hazardous Environment... 

However, the standard used in the United States and the standards used in Europe do not coincide. The dissimilarities are due to a difference in the manner in which hazardous environments are classified and to a divergence in philosophy over the safety factor employed. NFPA 493 uses a safety of 1.5 pertaining to the total energy, while the International Electrotechnical Commission (IEC) and European Committee for Electrotechnical Standardization (CENELEC) require a safety factor of 1.5 for the voltage or current, which relates to a 2.25 factor of safety for the energy. 

The normal operation shall not be capable of igniting the hazardous environment when adjusted for its worst operating conditions and an additional energy factor of 1.5 is introduced ... 

The circuit must be incapable of igniting the hazardous environment when operated at 1.5 its energy rating and the inducement of one fault and its related failures. Further, the circuit must be incapable of igniting the hazardous environment at its normal energy rating when two faults and their associated failures are introduced ... 

The first task, which should be completed before considering the design of any facility or equipment involving energetic material, is to define exactly what type of hazardous environment will be involved in each room, section or area. This is a prerequisite, whether selecting intrinsically safe or any other technique to provide electrical protection. 

The Explosives Environment. The Army Materiel Command (AMC), which has the primary responsiblity for manufacture and storage of explosives for the Department of Defense, clarified its definition of the type of hazardous location involved with explosives, propellants, and pyrotechnics in its most recently revised safety manual (4). When the only consideration for hazardous environment is the presence of explosive material, it recommends that the environment be classified as Class II, Group G, with the appropriate division based on the probability of the hazardous element being present in the environment. It further states that consideration must be given to vapors which might be present or to the presence of metallic dust. 

Circuits Not Device. During design, when considering the use of intrinsically safe electrical circuits, the whole electrical circuit must be considered. It is not enough just to consider the electrical apparatus employed in the hazardous environment. Consideration must be given to its associated apparatus located in the non-hazardous area. Therefore, it is not just the apparatuses which must be considered, but the whole circuit, both in the hazardous area and the non-hazardous area. 

Additional Requirements. In addition to electrical and physical isolation requirements, the surface temperature of all equipment and wiring located in the hazardous environment must not exceed the values indicated in the standard. 

Availability. Both Underwriters Labatories and Factory Mutual Research publish yearly guides to electrical equipment which they have certified and continue to certify as being rated for use in hazardous environments. Many of the items contained in these guides are rated as intrinsically safe or as associated equipment for use with intrinsically safe equipment. Further, the amount of equipment available should increase each year as the demand increases for intrinsically safe electrical circuits. 

As mentioned earlier, pneumatic and hydraulic systems have been extensively used in hazardous environments to provide the power necessary to move and drive machinery to complete needed tasks. Their use has demanded development of complex logic systems which involve the addition of valves and piping. These logic control systems are often hard to design, debug, construct, and maintain. 

Another new important tool for use in hazardous locations is robotics. This tool allows the operator to be removed from the hazardous environment to a location away from the danger, affording the operator maximum safety. 

Capp, B. and Widginton, D.W., "The Intrinsic Safety of Resistive Circuits", 2nd International Conference on Electrical Safety in Hazardous Environments, 9-11 Dec 1975, pages 43-47 Electrical Equipment for Hazardous Locations, Underwriters Laboratories, Inc., Northbrook, IL... 

Redding, R.J., "The Use of Solid State Circuitry Within Hazardous Areas", 3rd International Conference on Electrical Safety in Hazardous Environments, 1-3 Dec 1982, pages 219-233 Weatherhead, D., "Intrinsic Safety", Measurement and Control, Vol 10 No. 9, Sept 1977, pages 341-349... 

The term dosage typically refers to an environmental hazard and is the product of the concentration of toxic gas or vapor at a particular point and the duration of the hazardous environment at that point. Thus, the dosage can be expressed as an average concentration multiplied by an average duration, or... 

Hazardous Materials Response Team(s) Establish the HazMat Group, and Provide Technical information/Assistance to Command, EMS Providers, Hospitals, and Law Enforcement. Detect/Monitor to Identify the Agent, Determine Concentrations and Ensure Proper Control Zones. Continually Reassess Control Zones, Enter the Hot Zone (with chemical personal protective clothing) to Perform Rescue, Product Information, and Reconnaissance. Product Control/Mitigation may be implemented in Conjunction with Expert Technical Guidance. Improve Hazardous Environments Ventilation, Control HVAC, Control Utilities. Implement a Technical Decontamination Corridor for Hazardous Materials Response Team (HMRT) Personnel. Coordinate and Assist with Mass Decontamination. Provide Specialized Equipment as Necessary. Assist Law Enforcement Personnel with Evidence Preservation/Collection, Decontamination. 

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