Enclosed atmosphere

Atmospheric Tanks The term atmospheric tank as used here applies to any tank that is designed to operate at pressures from atmospheric through 3.45 kPag (0.5 psig). It may be either open to the atmosphere or enclosed. Atmospheric tanks may be either shop-fabricated or field-erected. The most common apphcation is storage of fuel for transportation and power generation. See the subsections Pressure Tanks and Pressure Vessels later in this section. 

Methods. Viscosity Measurements. Crosslinking reactions and reactions with butyl isocyanate were carried out in an Ubbelohde suspended-level viscometer modified to enable reactions to be carried out in an enclosed atmosphere. Viscometers were immersed in an oil bath at 80°C., and flow times were measured over periods of up to 10 days. Specific viscosities, 77, were then calculated. In general, runs were followed until the change in viscosity with time had become very small. Flow times were measured frequently enough to allow a smooth curve to be drawn when rj was plotted against reaction time a typical curve is... 

A batch unit, the HP-hybrid filter press is typically used for products with specialty chemicals volumes in the range of500-3000 gallon batches. Products are processed in an enclosed atmosphere without operator or environmental exposure. FDA requirements, and conformation to good manufacturing practices (GMP) requiring containment of product, are continual issues. Applications are replacement of plate and frame filter presses, and products that are compressible and amorphous in nature with high specific cake resistances. 

Kalandarov S, Bychkov VP, Frenkel ID, et al. 1984. [Effect of an increased ammonia content in an enclosed atmosphere on the adrenocortical system in man.] Kosm Biol Aviakosm Med 18 75-77. (Russian)... 

The same goes if we use an enclosed atmosphere in a closed system, and add some methylmercury in the gaseous state. We will have some methylmercury dissolved in water and some attached to particles. Of course, we can change this equilibrium, and addition of more organics will get some of that from the atmosphere down in the waters and further onto the fish. But if we flush away the methylmercury in the atmosphere, we get the same quick equilibrium. In these closed laboratory systems, it is comparatively quickly that we regain equilibrium. 

Contamination by airborne basic substances such as amines and N-methylpyrrolidone (NMP) has been shown to be responsible for the formation of the surface insoluble layer. Because of the catalytic nature of the imaging chemistries, a trace amount on the order of 10 ppb of airborne basic substances absorbed in the resist film interfaces with desired acid-catalyzed reactions, and also certain polymers and groups can function as internal contamination. Activated carbon filtration of the enclosing atmosphere can alleviate the contamination problem. Application of a protective... 

Aqueous solutions can be scanned up to and through sublimation to observe solute behavior. The heats of fusion of materials which require an enclosed atmosphere (e.g., water vapor evolved in dehydration below 100°C). 

Another option available with rotary vacuum dmm filters is fiiU enclosure. This enables operation under nitrogen or other atmospheres, for reasons such as safety, prevention of vapor loss, etc. Enclosure may also be used to prevent contamination of the material being filtered or to confine the spray from washing nozzles. The rotary dmm filter also can be enclosed in a pressure vessel and operated under pressure. 

Another possibiUty is to enclose only the working, top part of the horizontal belt in a pressure vessel and pass the belt through the sides of the vessel. The operation must be intermittent because the belt cannot be dragged over the support surface with the pressure on, and the entrance and exit ports for the belt must be sealed during operation to prevent excessive losses of air. The movement of the belt is intermittent and is synchronized with decompression in the vessel therefore, the entire vessel volume must be depressurized in every cycle and this is wasteful. There is also an inevitable downtime. There are no problems with discharging the cake because this is done at atmospheric pressure. 

Vacuum and Atmosphere Melting. A coreless high frequency induction furnace is enclosed in a container or tank which can be either evacuated or filled with a gaseous atmosphere of any desired composition or pressure. Provision is made for additions to the melt, and tilting the furnace to pour its contents into an ingot mold also enclosed in the tank or container without disturbing the vacuum or atmosphere in the tank (Fig. 2). 

Continuous Pressure Filters These filters consist of conventional drum or disk filters totally enclosed in pressure vessels. Filtration takes place with the vessel pressurized up to 6 bar and the filtrate discharging either at atmospheric pressure or into a receiver maintained at a suitable backpressure. Cake discharge is facilitated through a dual valve and lock-hopper arrangement in order to maintain vessel pressure. Alternatively, the discharged filter cake can be reslurried within the filter or in an adjoining pressure vessel and removed through a control valve. 

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