Equipment characteristics desired

General Characteristics Countercurrent flow is maintained by virtue of the difference in densities of the hquids and either the force of gravity (vertical towers) or centrifugal force (centrifugal extractors). Only one of the liquids may be pumped through the equipment at any desired velocity. Tne maximum velocity for the second is then fixed if it is attempted to exceed this limit, the second hquid will be rejected and the extractor will be flooded. 

The types of sedimentation encountered in process technology will be greatly affected not only by the obvious factors—particle size, hquid viscosity, sohd and solution densities—but also by the characteristics of the particles within the shiny. These properties, as well as the process requirements, will help determine both the type of equipment which will achieve the desired ends most effectively and the testing methods to be used to select the equipment. 

Problem Definition InteUigent selection of a separator requires a careful and complete statement of the nature of the separation problem. Focusing narrowly on the specific problem, however, is not sufficient, especi ly if the separation is to be one of the steps in a new process. Instead, the problem must be defined as broadly as possible, beginning with the chemical reactor or other source of material to be separated and ending with the separated materials in their desired final form. In this way the influence of preceding and subsequent process steps on the separation step will be iUuminated. Sometimes, of course, the new separator is proposed to replace an existing unit the new separator must then fit into the current process and accept feed materials of more or less fixed characteristics. At other times the separator is only one item in a train of new equipment, all parts of which must work in harmony if the separator is to be effective. 

Ultrafiltration equipment are combined with other unit operations. The unique combination of unit operations depends on the wastewater characteristics and desired effluent quality, and cost considerations. 

The desirable operating characteristics of equipment include simplicity, convenience and low cost of maintenance simplicity, convenience and low cost of assembly and disassembly convenience in replacing worn or damaged components ability to control during operation and test before permanent installation continuous operation and steady-state processing of materials without excessive noise, vibration or upset conditions a minimum of personnel for its operation and, finally, safe operation. Low maintenance often... 

The field of surface-mediated synthesis of metal carbonyl clusters has developed briskly in recent years [4-6], although many organometallic chemists still seem to be unfamiliar with the methods or consider themselves ill-equipped to carry them out. In a typical synthesis, a metal salt or an organometallic precursor is brought from solution or the gas phase onto a high-area porous metal oxide, and then gas-phase reactants are brought in contact with the sample to cause conversion of the surface species into the desired products. In these syntheses, characteristics such as the acid-base properties of the support influence fhe chemisfry, much as a solvenf or coreactant influences fhe chemisfry in a convenfional synfhesis. An advanfage of... 

T) Spin Test. The purpose of this test is to check the arming characteristics of a fuze for spin-stabilized ammunition. The equipment consists of a vertical spindle that has an adapter to accommodate the test fuze. The spindle is rotated at the desired rpm by an electric motor or air. In some procedures a stroboscope is used to observe the arming characteristics of the mechanism (p IIB-26 of Ref 39)... 

Z) Walking Bearn Test. The purpose of this fuze test is to det the operating characteristics of pressure-actuated fuzes. The test consists of placing the test fuze under the end of a rod that is attached to the test equipment. A hydraulic hand pump, which is a part of the equipment is operated behind a barticade with the desired load being applied to the fuze (p IIB-40 of Ref 39)... 

The success in manufacturing the tablet formulation (with varying batch sizes of 250-900 kg) and achieving reproducible tablet physical results was due in part to the robustness of the formulation design and the active drug s compressibility characteristics. Illustration of the different particle size distributions observed and equipment parameters employed to achieve the desired results are noted in Tables 1 to 3 (1). 

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