Heater block

The common heater block shown in Fig. 19.23 can itself be subject to corrosion leading to different heat transfer conditions for different tubes, and in some later versions of the apparatus individual short heating jackets are used for each tube, which are heated with oil from either a steam-heated or electrically heated heat exchanger. This modification not only avoids corrosion problems but also obviates the necessity to machine a length of the outside of each tube to fit the semi-circular notches in the single heater block. The oil flow is adjusted to give an oil temperature of 95°C at each outlet. 

The conditions under which the material is tested are crucial. The top of the exposure chamber must be sealed and the tank should contain no free air space. A stirring mechanism in the tank keeps the leachate mixture homogeneous and a heater block keeps it at an elevated temperature as required for the test. Stress conditions of the material in the field should also be simulated as closely as possible. The original U.S. EPA Method 9090 test included a rack to hold specimens under stress conditions but was revised when some materials shrank in the leachate. Due to the hazardous nature of the material, testing should be performed in a contained environment and safety procedures should be rigorously followed. 

Elevated Temperature Studies. The Varian 5000 liquid chromatograph and a Waters Associates 401 differential refractometer were employed. The column was heated with a Varian universal heater block at an estimated accuracy of 0.5 C. About 15-30 minutes were allowed for column equilibration for a given temperature. The recorder employed was a Varian 9176. 

Temperature regulation of the extraction module was accomplished through the use of a solid state controller regulating two cartridge heaters imbedded in an aluminum heater block that surrounded the extraction chambers. Fluid entering the extraction chambers was pre-heated in coils of tubing imbedded in the heater block and the extractant valves as well as the extractant lines were directly attached to the heater block to maintain temperature. 

For hydrogenation the samples were exposed for 1-19 h to a remote hydrogen and/or deuterium dc plasma in a parallel plate system, with a plate voltage of 1000 V. The samples were mounted on a heater block held at a temperature of 150-380 °C and placed 10 cm downstream from the plasma with a bias voltage of about 300 V, which fixed the bias current to 40 pA. The gas pressure was held at 1 mbar. 

Close contact of the wafer to the surface of the heater block is another important factor that determines uniformity and reproducibility of the deposition. In addition, the heating time of the wafer to the desired temperature after chamber loading, which takes normally a few minutes and reduces throughput, also depends on the contact status. The electrostatic chuck (ESC) may... 

The experimental evaporator (micro two-phase jets generator) is shown on Fig. 10 -11. The heater block of the evaporator includes a hole machined directly in the centre of the copper cylinder with thick walls and is used for the installation of a nickel sintered powder evaporator. Some thermocouples are disposed inside the copper block to control the heat flow to the evaporator from the electric heater disposed on its outer surface. To minimize heat losses, the heater block was insulated. Heat input to the evaporator was calculated by conduction analysis using thermocouples that were placed at a known distance apart in the copper heater block. 

Figure 13.4 Sample inlet systems (a) Hypodermic needle syringe and heater block for liquids, (b) gas sample introduction.

The sample is contained in a 1 by 10-mm diameter indentation machined in the surface of a silver heater block. The circular block is 25 mm in diameter and it is heated by two 2.6-Q Nichrome wire heaters. It is contained in an enclosure, 55 mm square and 13 mm thick. The heater is thermally insulated from the main body of the sample holder by a thin layer of ceramic fiber insulation. The sample side of the holder is enclosed by a quartz plate, 50 mm on an edge by 2 mm thick, which is held firmly in place by two metal strips. Each metal strip is fastened to the holder by two thumb screws they (and hence the cover plate) can easily be removed to facilitate sample... 

Details of the complete EC-DTA cell are shown in Figure 11.256. The heater block, which was machined from aluminum, contained a 500 W heater cartridge located in the center of the block. Two cylindrical chambers located on each side of the heater housed the sample and reference container, respectively. Care was taken to position each container at exactly the same distance from the heater. It was found from previous DTA studies that the diameter of the con tainer cavities greatly influenced the DT A curves obtained. In this cell they were 18 mm in diameter by 38 mm in depth. 

The TREF part of their cross fractionation system is housed in a heater block to allow the use of an injector loop and to heat the valving system needed to deliver the TREF fraction solution to the SEC. Column volume and sample size, solvent and concentration are directed by needs of the SEC analysis. They achieved a workable system with 15 x 0.8 cm colunm packed with 3.5 g of glass beads. The polymer (20 mg) was loaded hot as a 1% solution in o-dichlorobenzene. The cooling step caused some problems due to diffusion of polymer species outside the column. They solved this problem by fast cooling the solution (100 K/hour) but clearly there is concern about the effect of this on the quality of the TREF separation. A dissolution period of 10 minutes during the stepwise TREF was... 

The idea of control over polymerization rate in a stirred-vessel FRRPP system has been extended to dimensional control of a quiescent polymerization film material. Polymerization was initiated in certain specific regions by directed radiation, similar to methods used in microlithography in microsystems. In a number of efforts, synchrotron X-ray was used as the radiation source and a 500-p.m thick photomask made of gold was employed (Tirumala 2003 Tirumala et al., 2003, 2004a,b,c, 2005a,b, 2006). Liquid reactive material containing monomer(s) and sol-vent/precipitant were sandwiched between two standard 8-in. Silicon wafers with a thin spacer material (Fig. 4.7.1). Heat is applied on the backside of the wafer system through a heater block of controlled temperature. 

Sy Cincubator (or heater block with microtitre attachment) and microtitre plate reader... 

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