Size requirements

In order to develop the proper dow pattern, knowledge of a material s dow properties is essential. Standard test equipment and procedures for evaluating sohds dow properties are available (6). Direct shear tests, mn to measure a material s friction and cohesive properties, allow determination of hopper wall angles for mass dow and the opening size required to prevent arching. Other devices available to evaluate sohds dowabiUty include biaxial and rotary shear testers. 

There are two mechanisms by which arching can occur particle interlocking and cohesive strength. The minimum outlet size required to prevent mechanical interlocking of particles is directly related to the size of the particles. The diameter of a circular outlet must be at least six to eight times the particle size, and the width of a slotted outlet must be at least three to four times the particle size. These ratios normally only govern the outlet size of mass flow hoppers if the particles are at least 0.6 cm or larger. 

If most of the particles are less than ca 0.6 cm in size, flow obstmctions can occur by physical, chemical, or electrical bonds between particles. This cohesiveness is characterized by the bulk material s flow function. The forces acting to overcome a cohesive arch and cause flow are described by a hopper s flow factor, which can be obtained from the design charts (see Fig. 7). The minimum opening size required to prevent a cohesive arch from forming can be calculated from the comparison of the flow factor and flow function. 

Reinforced Thermoplastic Sheet. This process uses precombined sheets of thermoplastic resin and glass fiber reinforcement, cut into blanks to fit the weight and size requirements of the part to be molded. The blanks, preheated to a specified temperature, are loaded into the metal mold and the material flows under mol ding pressure to fiU the mold. The mold is kept closed under pressure until the temperature of the part has been reduced, the resin solidified, and demolding is possible. Cycle time, as with thermosetting resins, depends on the thickness of the part and the heat distortion temperature of the resin. Mol ding pressures are similar to SMC, 10—21 MPa (1500—3000 psi), depending on the size and complexity of the part. 

Design Features There are three classes of thickeners, each differentiated by its drive mechanism (1) bridge-supported, (2) center-column supported, and (3) traction drives. The diameter of the tank will range from 2 to 150 m (6.5 to 492 ft), and the support structure often is related to the size required. These classes are described in detail in the subsection Components and Accessories for Sedimentation Units. ... 

NFPA 30 and API Standard 2000 provide gmdance for design of overpressure protec tion involving storage tanks that operate at or near atmospheric pressure. In particular, NFPA 30 focuses on flammability issues, while API 2000 addresses both pressure and vacuum requirements. The ASME code (Sections I and TII) and API RP 520 are the primaiy references for pressure rehef device sizing requirements. 

Assume the temperature of the busbars at the time of fault = 85°C and rectangular flats of electrolytic grade E-91E or its equivalent. Busbars chosen for each phase - four (152.4 mm X 6.35 mm) - which are more than the minimum size required to account for the thermal effects during a short circuit condition... 

I will use an MPP toroid core. The core sizing procedure is contained in Section 3.5.5. Estimate the core size required ... 

Samples must be introduced into the plasma in an easily vaporized and atomized form. Typically this requires liquid aerosols with droplet diameters less than 10 pm, solid particles 1-5 pm in diameter, or vapors. The sample introduction method strongly influences precision, detection limits, and the sample size required. 

Size requirements are limited by packaging considerations for neutron irradiation. Typically, polyethylene or quartz containers are used to contain the sample in the reactor core. For example. Si wafers are cleaved into smaller pieces and dame sealed... 

The RSST can rapidly and safely determine the potential for runaway reactions. It also measures the temperature rates and, in the case of gassy reactions, pressure increases to allow reliable determinations of the energy and gas release rates. This information is combined with analytical tools to evaluate reactor vent size requirements. This is extremely useful when screening a large number of different chemicals and processes. 

The first two eases represent the smallest and largest vent sizes required for a given rate at inereased pressure. Between these eases, there is a two-phase mixture of vapor and liquid. It is assumed that the mixture is homogeneous, that is, that no slip oeeurs between the vapor and liquid. Furthermore, the ratio of vapor to liquid determines whether the venting is eloser to the all vapor or all liquid ease. As most relief situations involve a liquid fraetion of over 80%, the idea of homogeneous venting is eloser to all liquid than all vapor. Table 12-3 shows the vent area for different flow regimes. 

Small size, requiring a relatively small installation area... 

Determine the rupture disk size required to relieve the pressure in a process vessel with the following conditions k = 1.4. 

Grolmes, M. A., Leung, J. C. and Fauske, H. K., Reactive Sy s-tems Vent Sizing Requirements, Proceedings of the Inter-nadonal Symposium on Runaw ay Reactions, CCPS, Cambridge, MA, March 1989. 

Systems of this size require large-diameter refrigerant suction and discharge pipes to connect the components of the complete... 

The widespread use of packaged units of all sizes requires interpretation of catalogue data by applications engineers, sales engineers, and others, and by the end user. 

FIGURE 11.24 Power curves. Abscissae is the sample size required to determine a difference between means shown on the ordinate. Numbers next to the curves refer to the power of finding that difference. For example, the gray lines show that a sample size of n = 3 will find a difference of 0.28 with a power of 0.7 (70% of the time) but that the sample size would need to be increased to 7 to find that same difference 90% of the time. The difference of 0.28 has previously been defined as being 95% significantly different. 

This latter value (tp) is given by power analysis software ancl can be obtained as a power curve. Figure 11.24 shows a series of power curves giving the samples sizes required to determine a range of differences. From these curves, for example, it can be seen that a sample size of 3 will be able to detect a difference of 0.28 with a power of 0.7 (70% of time) but that a sample size of 7 would be needed to increase this power to 90%. In general, power analysis software can be used to determine sample sizes for optimal experimental procedures. 

Desktop tools address design and manufacturing concerns such as gate placement, injection time/rate, injection pressure, melt and mold temperatures, packing time and pressure, cooling time requirements, and machine size requirements. 

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