Enclosure to

The speed of the pickle reaction is also dependent on the concentration and temperature of the pickle, the degree of agitation of either the metal part or the pickle solution, the alloy being pickled, and the acid used. Pickling solutions may be appHed by either spray or immersion techniques. However, because of the noxious fumes emitted, there must be adequate ventilation. Sometimes, particularly when spraying techniques are used, an enclosure to contain the fumes and mist is employed. 

One feature of reprocessing plants which poses potential risks of a different nature from those ia a power plant is the need to handle highly radioactive and fissionable material ia Hquid form. This is necessary to carry out the chemical separations process. The Hquid materials and the equipment with which it comes ia contact need to be surrounded by 1.5—1.8-m thick high density concrete shielding and enclosures to protect the workers both from direct radiation exposure and from inhalation of airborne radioisotopes. Rigid controls must also be provided to assure that an iaadvertent criticahty does not occur. 

Locate vulnerable instruments within protective enclosures to prevent accidental breakage... 

A motor cart be constructed in different enclosures to suit a particular location as follows. 

We have defined the various types of enclosures adopted by various manufacturers to suit different locations and environmental conditions in Tables 1.10 and 1.11. Here we briefly discuss methods for testing these enclosures to check their compliance with defined requirements. 

In outdoor type switchgear or controlgear assemblies the normal practice is to provide a double door in the front to house the front panel and protect the door knobs, meters, lights, pushbuttons, reset knobs or other accessories mounted on the door and thus prevent water or dust leaking through joints, knockouts and fitments etc. It is also recommended to have a canopy on the top of the enclosure to protect the panel from direct rain. Figures 13.6 and 13.28 illustrate this type of construction. 

This test is applicable to all outdoor metal-enclosed switchgear and controlgear assemblies, as in lEC 60298, lEC 60694 and ANSI C-37/20C. The enclosure to be tested should be complete in all respects including its mounts, bushings (for HT switchgear assemblies, 1 kV and above) and wiring. One or more vertical units can be tested simultaneously as may be convenient, but not more than 3 m panel width can be tested at a time. For a multiple unit switchboard, however, at least two vertical units should be tested together to check the joints between the units. 

In this conslmction the conductors of each phase tire housed in a separate non-magnetic metallic enclosure to isolate them completely from each other with the following ad antages ... 

This test is applicable to all outdoor parts of any bus system and on both indoor and outdoor parts of an isolated phase bus (IPB) system. Each enclosure to be tested (such as the enclosure of one phase in an isolated phase bus system) should be complete in all respects with all its fittings and mounts in place. The length of the testpiece must be the same as that considered for the temperature rise test (Section 32.3.4). 

While some video display screens such as liquid crystal, gas plasma or vacuum fluorescent displays do not present the same charged screen hazards as CRTs, this does not imply that they are safe for use in hazardous locations. This requires special design and certification for use with a given flammable atmosphere. Non-certified equipment used in locations classified as hazardous under Article 500 of NFPA 70 National Electrical Code require a purged or pressurized enclosure to control ignition hazards as described in NFPA 496 Standard for Purged and Pressurized Enclosures for Electrical Equipment. The screen in this case is located behind a window in the enclosure. 

Cooling tower fan motors must be properly selected for long life and trouble free operation. In addition, it is important to match the motor s enclosure to the application. Motors in draw through applications that are mounted directly in the air stream, for example, experience tough duty and must be of the totally enclosed type. Motors are categorized as follows ... 

A gas expands in an enclosure to fill up the entire space, while a liquid presents a free surface in contact with the gas boundary above it. 

For enclosures, velocity measurements, in the plane of the opening, offer a quick check on the design conditions. Fiowever, the opening velocity is not a direct measure of the ability of an enclosure to provide personnel protection. Other measures of efficiency are required and depend on use of the enclosure. In the case of safety cabinets and laboratory hoods, allowance factors for protection and leakage are applied to ensure complete safety when in use. 

Induced leakage Leakage into an enclosure to equalize a pressure difference due to natural or mechanical ventilation. 

Pressure piling is a phenomenon caused by the fact that ignition in an enclosure can first pre-compress gases in a conduit or other enclosure to... 

A dust-ignition-proof machine is a totally enclosed machine whose enclosure is designed and constructed in a manner which will exclude ignitable amounts of dust or amounts which might affect performance or rating, and which will not permit arcs, sparks, or heat otherwise generated or liberated inside of the enclosure to cause ignition of exterior accumulations or atmospheric suspensions of a specific dust on or in the vicinity of the enclosure. 

That the authorities have refused unreasonably to accept compliance with alternative requirements or that the requirements of the notice are otherwise unreasonable in character or extent, or are unnecessary. This defense is self-explanatory. The local authorities are only permitted to ask for works that will abate the noise nuisance. Other works (perhaps to comply with legislation) should not be specified in the notice. They may, however, be contained in a letter separate from the notice. An example of this would be where the fitting of acoustic enclosures to food-manufacturing machines breached food hygiene requirements. Readily cleanable enclosures may be a requirement of the Food Hygiene Regulations, but it should not be contained in a Section 58 Control of Pollution Act notice. 

Skin protection may necessitate use of full protective suits. When catalysts are dumped from reactors at the end of a process they may prove to be extremely dusty as a result of reduction in particle size during the reaction process. Again, depending upon the nature of the hazard, ventilation, personal protection, and use of temporary enclosures to prevent contamination of the general work area should be considered. Some catalysts are pyrophoric and some catalyst beds are inerted with the added possibility of fire, or release of inerting gas into the workplace which may cause asphyxiation. 

A confined explosion occurs when there is a rapid combustion of a fuel and an oxidizer inside an enclosure (e.g., building, vessel, or duct), developing sufficient pressure to cause the enclosure to rupture. Examples of confined explosions include gas or dust explosions inside buildings, storage tanks, or process equipment. 

The correct application of either sizing technique will result in a duct network that works well on air. It is equally important to ensure that each air flow is adequate to transfer all the particulates from the hood/enclosure to the collection and/or cleaning device. Unfortunately, many dust control systems have been designed and/or are being operated with little or no regard for what actually has to go through the hood-duct network. This can result in ... 

L2 is the second smallest dimension of the enclosure to be vented, and P is the maximum internal pressure that can be withstood by the weakest member of the enclosure. 

More than adequate area exists on the outer wall of the enclosure to accommodate this vent. 

A chemical reactivity hazard, as the term is used in this publication, is a situation with the potential for an uncontrolled chemical reaction that can result directly or indirectly in serious harm to people, property or the environment. The uncontrolled chemical reaction might be accompanied by a temperature increase, pressure increase, gas evolution or other form of energy release. It need not be explosive to result in serious harm. For example, gases evolved from a chemical reaction can be flammable, toxic, corrosive, hot, or can pressurize an enclosure to the point of rupture. 

Although the use of enclosures is conceptually the simplest approach, some particular problems arise in their use in studies of NH3 loss. These are associated with the chemical reactivity of the gas, particularly its reactivity with water, and to the strong influence of environmental factors on the volatilization process (11). Matching conditions within the enclosure to those prevailing outside is a difficult task and much of the data obtained using enclosures is open to question. However, the problems associated with enclosures can be overcome if the air speed through the enclosure is controllable to within the same range as that of wind speed at the experimental site (9, 12). 

For enclosed process structures, any inside stairs that serve as an exit or exit component require enclosure to provide personnel protection from smoke and fire during emergency egress. The stair enclosures serving as an exit way must have the following fire-resistive construction ... 

This type of system may be used for the extinguishment of surface fires in flammable liquids, gases, and solids where the hazard is not enclosed. Examples of hazards that may be successfully protected by local application systems include dip tanks, quench tanks, and spray booths. Since local application systems do not utilize enclosures to maintain design concentrations, two methods for determining the quantity of carbon dioxide required for extinguishment are used. These are ... 

The amount of air that can be drawn into an enclosure to support combustion will depend on both the size and configuration of ventilation openings in the enclosure. A poorly ventilated fire will create more smoke and byproducts. Any unburnt fuel may also burn outside the enclosure, endangering adjacent areas. A fire in a structure may also cause other fuels to burn such as cables, paint, plastic equipment etc. These will add to the fuel load and to the smoke. 

The system in its current configuration is shown in Fig. 6.9. Since 1988, the system has been moved from a bench top to a custom vented enclosure to minimize exposure to organic fumes. The detectors, solvents and other necessary support devices are located below the robot work surface. Functionally, the robot still performs almost the same procedure as the initial system (dilution of samples), but there are a number of key differences. 

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