Model laboratory

The scale-up of filtration centrifuges is usually done on an area basis, based on small-scale tests. Buchner funnel-type tests are not of much value here because the driving force for filtration is not only due to the static head but also due to the centrifugal forces on the Hquid in the cake. A test procedure has been described with a specially designed filter beaker to measure the intrinsic permeabiHty of the cake (7). The best test is, of course, with a small-scale model, using the actual suspension. Many manufacturers offer small laboratory models for such tests. The scale-up is most reHable if the basket diameter does not increase by a factor of more than 2.5 from the small scale. 

Discs range in size from laboratory models 30 cm in diameter up to production units of 10 meters in diameter with throughputs of 100 ton/hr. Figure 20-82 shows throughput capacities for discs of varying diameter tor different applications and formulation feed densities. When scaling up from laboratoiy or pilot tests it is usual to keep the... 

FIGURE I 2.31 Enclosure with 3 containment source S and a laboratory model with a model source S,... 

FIGURE I2.3B Flim-devetoping machine and a laboratory model. 

FIGURE 12.39 (o) Vortex exhaust at a concrete element factory, h laboratory model of the vortex exhaust, and (c) stmpIKIed model of the exhaust. 

Mathematical models have also predicted a low volatility for methyl parathion (Jury et al. 1983 McLean et al. 1988). One study using a laboratory model designed to mimic conditions at soil pit and evaporation pond disposal sites (Sanders and Seiber 1983) did find a high volatility from the soil pit model (75% of the deposited material), but a low volatility for the evaporation pond model (3. 7% of the deposited material). A study of methyl parathion and the structurally similar compound ethyl parathion, which have similar vapor pressures, foimd that methyl parathion underwent less volatilization than ethyl parathion in a review of the data, the reduced level of volatilization for methyl parathion was determined to be due to its adsorption to the soil phase (Alvarez-Benedi et al. 1999). 

Gile JD, Gillett JW. 1981. Transport and fate of organophosphate insecticides in a laboratory model ecosystem. J Agric Food Chem 2 616-621. 

The effects of microsphere size distribution, drug/polymer ratio, and microsphere quality can be easily demonstrated in this laboratory model. Furthermore, as animal data and human clinical trial results are available the model becomes quite useful as a quality control method (46). 

J. P. Salanitro, M. P. Williams, and G. C. Langston. Growth and control of sulfidogenic bacteria in a laboratory model seawater flood thermal gradient. In Proceedings Volume, pages 457-467. SPE Oilfield Chem Int Symp (New Orleans, LA, 3/2-3/5), 1993. 

ABC Laboratories Model SP 1000 gel permeation chromatograph system equipped with a 31.0 X 2.5-cm glass column of Envirobeads SX-3 select 200 00 mesh (ca 60 g) preconditioned with ethyl acetate-cyclohexane (1 1, v/v)... 

Example 2-3 Scale-Up of Pipe Flow. We would like to know the total pressure driving force (AP) required to pump oil (/z = 30 cP, p = 0.85 g/cm3) through a horizontal pipeline with a diameter (D) of 48 in. and a length (L) of 700 mi, at a flow rate (Q) of 1 million barrels per day. The pipe is to be of commercial steel, which has an equivalent roughness (e) of 0.0018 in. To get this information, we want to design a laboratory experiment in which the laboratory model (m) and the full-scale field pipeline (f) are operating under dynamically similar conditions so that measurements of AP in the model can be scaled up directly to find AP in the field. The necessary conditions for dynamic similarity for this system are... 

Small, properly scaled laboratory models operated at ambient conditions have been shown to accurately simulate the dynamics of large hot bubbling and circulating beds operating at atmospheric and elevated pressures. These models should shed light on the overall operating characteristics and the influence of hydrodynamics factors such as bubble distribution and trajectories. A series of different sized scale models can be used to simulate changes in bed behavior with bed size. 

Lu, P.Y., Metcalf, R.L., Carlson, E.M. (1978) Environmental fate of five radiolabelled coal conversion by-products evaluated in a laboratory model ecosystems. Environ Health Perspect. 24, 201. 

Lu, P Y., R.L. Metcalf, and L.K. Cole. 1978. The environmental fate of 14C pentachlorophenol in laboratory model ecosystems. Pages 53-63 in K.R. Rao (ed.). Pentachlorophenol Chemistry, Pharmacology, and Environmental Toxicology. Plenum Press, New York. 

Lu, P.-Y., R.L. Metcalf, N. Plummer, and D. Mandrel. 1977. The environmental fate of three carcinogens benzo-(a)-pyrene, benzidine, and vinyl chloride evaluated in laboratory model ecosystems. Arch. Environ. Contam. Toxicol. 6 129-142. 

Zyromska-Rudzka, H. 1966. Abundance and emigrations of Tribolium in a laboratory model. Ekol. Pol. [A] 14, 491-518. 

The theory and understanding required to deal quantitatively with spills was initially provided by Van Dam (1967), who also illustrated the physical processes responsible for product accumulation in wells and adjacent porous media. The relationship between actual and apparent thicknesses using a physical laboratory model was developed by Zilliox and Muntzer (1975), who proposed the following equation ... 

These variables are illustrated in Figure 6.10. Zilliox and Muntzer (1975) also evaluated the effects of falling and rising water tables on Ah in their Plexiglas laboratory model. When the water table fell, the capillary pressures Pc vo and PcOA were nearly equal, whereas Ah was positive at equilibrium. When the water table rose, they observed that P°A varied little and Pcwo decreased considerably. As a result, Ah decreased and could become negative. Hence, the actual thickness could be greater than the apparent thickness. 

Cavero, 1. and Crumb, W.J. (2001) Native and cloned ion channels from human heart laboratory models for evaluating the cardiac safety of new drugs. European Heart Journal Supplements, 3, K53-K63. 

Application of radiolabeled mirex to plants grown in a terrestrial/aquatic laboratory model ecosystem indicated that when the plant leaves were eaten by caterpillars, the aquatic system became contaminated. Mirex was detected in all segments of two aquatic food chains (alga > snail and plankton > daphnia > mosquito > fish) within 33 days. Undegraded mirex contributed to over 98.6, 99.4, 99.6, and 97.9% of the radiolabel in fish, snails, mosquitoes, and algae, respectively. No metabolites of mirex were found in any of the organisms (Francis and Metcalf 1984 Metcalf et al. 1973). 

Francis BM, Metcalf RL. 1984. Evaluation of mirex, photomirex and chlordecone in the terrestrial aquatic laboratory model ecosystem. Environ Health Perspect 54 341-346. 

One major difficulty has been that no convincing laboratory model of the drug s clinical effect has yet been established. This has not only hampered mechanistic investigations but has also prevented the rational search, by medicinal chemists, for more specifically effective anti-hypertensive 3-blocking agents. New drug candidates appear to have been selected on the basis of the laboratory pharmacological profile of the molecule and how this profile relates to one or other of the various mode-of-... 

---