Vacuum suction table

Treatment of Tapa Cloth with Special Reference to the Use of the Vacuum Suction Table... 

The treatment of ethnographic artifacts like tapa cloth require an understanding of the material and its manufacture. The literature of the conservation of tapa is reviewed, and new techniques for filling voids are presented. These techniques include the use of hand-cast fills, and fills cast on the vacuum suction table. Case studies from 1980,... 

The most successful application of the vacuum suction table to the treatment of tapa cloth clearly was the formation of cast fills for filling voids. As with the hand-cast fills, pulp was created from hand-made Japanese papers. The benefit of using the suction table, however, was that no adhesive was necessary to attach the pulp to the edges of the voids. 

Meredith Montague, Assistant Conservator, Materials Conservation Laboratory, Texas Memorial Museum, carried out the replication of the experiments done with the vacuum suction table, and completed the treatment of the unnumbered tapa from the University s Department of Textiles and Clothing. 

The gas is applied as a mixture to the retentate (high pressure) side of the membrane, the components of the mixture diffuse with different rates through the membrane under the action of a total pressure gradient and are removed at the permeate side by a sweep gas or by vacuum suction. Because the only segregative mechanisms in mesopores are Knudsen diffusion and surface diffusion/capillary condensation (see Table 9.1), viscous flow and continuum (bulk gas) diffusion should be absent in the separation layer. Only the transition state between Knudsen diffusion and continuum diffusion is allowed to some extent, but is not preferred because the selectivity is decreased. Nevertheless, continuum diffusion and viscous flow usually occur in the macroscopic pores of the support of the separation layer in asymmetric systems (see Fig. 9.2) and this can affect the separation factor. Furthermore the experimental set-up as shown in Fig. 9.11 can be used vmder isobaric conditions (only partial pressure differences are present) for the measurement of diffusivities in gas mixtures in so-called Wicke-Callenbach types of measurement. 

Recent improvements in the sensitivity IS) of the vacuum-suction fiberdrawing technique for elongational viscosity measurements have permitted the evaluation of cellulose-thickened coatings with a small-particle latex 16), The data (Table I) indicate that the DUEV involves contributions not only from the thickener but also from the components of the formulation. On the basis of earlier observations 17), this contribution was assumed to arise from high-aspect ratio flocculents formed by the latex and pigment in extension. 

A useful summary of the typical equipment used for developing and maintaining process system vacuum is presented in Table 6-1. Also see Birgenheier [33]. The positive displacement type vacuum pumps can handle an overload in capacity and still maintain essentially the same pressure (vacuum), while the ejectors are much more limited in this performance and cannot maintain the vacuum. The liquid ring unit is more like the positive displacement pump, but it does develop increased suction pressure (higher vacuum) when the inlet load is increased at tlie lower end of the pressure performance curve. The shapes of these performance curves is important in evaluating the system flexibility. See later discussion. 

Bioslurping uses a vacuum to extract NAPL and water from the subsurface soil (Figure 7.18). A small-diameter well is installed so that the well screen is open slightly above and below the water table. A smaller-diameter dip tube is inserted into the well and sealed against the outer well casing. The dip tube does not extend to the bottom of the well, but ends below the water table (or oil-water interface). The maximum depth of the bottom of the slurp tube is the suction-lift capacity of the vacuum pump. 

Four of the many varieties of these units are illustrated in Figure 7.19. Performances and comparisons of five types are given in Tables 7.8-7.9. All of these types also are commonly used as vacuum pumps when suction and discharge are interchanged. 

Fig. 1.90.2. Scheme of the condenser design in plant PI 1 in Table 1.12.6. 1, Condenser wall 2, condenser coil 3, suction tube of vacuum pump 4, water drain 5, connection to drying chamber 6, valve with seal in closed position 7 valve in open position... 

The pressure in the deodorizer is always slighlty higher (0.5-1.5 mbar) than on the suction side of the vacuum unit, because of pressure losses caused by the oil demisters, the fatty matter scrubbers, and other equipment. Consequently, to reach an effective deodorization pressure of 2 mbar, a pressure of not more than 1.5 mbar at the suction side is required. To obtain an efficient steam sublimation at this low pressure, special stripping steam condensers operating at extremely low temperatures (—30°C) are required. (Table 19). 

The annual cost of operating a vacuum system is several times the equipment cost. So, a detailed review of the operating cost of a vacuum system is essential. For example, use of chilled water instead of cooling water can reduce steam/power consumption of the vacuum system. It also eliminates cavitation problems associated with LRVPs used at low suction pressures. Although chilled water is costlier than cooling water, it can be attractive if the electricity price is low or waste heat is available for chilled water production. Selection of SJE, LRVP, DVP, SJE-LRVP or SJE-DVP combination depends on many factors listed in Table 11.1. 

Table 16.30 Lower Limits of Suction Pressure and Capacities of Vacuum Systems"...

Filtration is a technique used for two main purposes. The first is to remove solid impurities from a liquid. The second is to collect a desired solid from the solution from which it was precipitated or crystallized. Several different kinds of filtration are commonly used two general methods include gravity filtration and vacuum (or suction) filtration. Two techniques specific to the microscale laboratory are filtration with a filter-tip pipette and filtration with a Craig tube. The various filtration techniques and their applications are summarized in Table 8.1. These techniques are discussed in more detail in the following sections. 

The voltage used for DC motors and solenoid valves is 24 volts. The diameter of each suction cup is 11.4 cm. The suction cups can create 34.5 kg force under 18 Hg vacuum according to the component catalog [20]. More specifications of the robot are given in the table 1. 

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