Vacuum desiccators charge for


In the premix operation, a uniform slurry of all components, except the oxidizer, is prepared. The premixes may contain cross-linking, wetting, opacifying, and antifoaming agents, plasticizers, metallic fuels, catalysts, and curing compounds. Automated techniques ensure formulation uniformity and reproducibihty. The polymer and other large-volume fluids required are pumped from the storage tanks to weigh tanks and then to the premix vessels. These may be up to 5000 L in capacity and equipped with turbine-driven agitators designed for the specific materials being handled. The secondary Hquid components, including a portion of the curing agent, are weighed, added, and mixed at a controlled temperature after first purging the premix vessel with nitrogen. The necessary soflds other than the oxidizer are screened and added, followed by further mixing under nitrogen, and finally under vacuum to remove entrapped gases. Batch mixers are temperature controlled and designed to deaerate the viscous mass while imparting a shear action to ensure thorough and rapid incorporation of soflds. They include relatively conventional horizontal mixers such as the sigma-blade dough mixer used in making nitrocellulose propellants, mixers with heavy-duty bear claw blades, and ribbon mixers. Vertical change-can planetary mixers are commonly used to meet requirements for increased mix capacity. Mixing times and temperatures are tightly controlled to maximize mix uniformity and minimize viscosity changes without accelerating the cure reactions to the stage where the pot life is excessively reduced. The mix temperature increases as a result of work input on the viscous mass and the exothermicity of the initial cure reaction. The required quantity of the premix is transferred to the mixer bowl, which is moved into position and assembled to the mixer. Mixing is begun after purging with nitrogen. When the process control conditions have been attained, the oxidizer is added followed by the curing agent. Mixing then proceeds under vacuum.  [c.49]

ASME Code design pressure (or maximum allowable working pressure), psi pressure on outlet side of rupture disk, psia exit or back pressure, psia, stamped burst pressure perimeter of a cross section, ft or meters Initial high pressure, mmHg maximum initial pressure at which the combustible atmosphere exists, psig initial pressure of system, psia initial low pressure or vacuum, mmHg maximum explosion pressure, bar, or other consistent pressure units maximum pressure developed in an unvented vessel, bar (gauge) or psig Normal expected or maximum expected operating pressure, psia  [c.538]


See pages that mention the term Vacuum desiccators charge for : [c.453]   
Textbook on organic chemistry (1974) -- [ c.138 ]