Heat conductive cartridge

FIGURE 2.93 Optimum mounting position of a heat conductive cartridge with a cooling area through conventional cooling channels (Source FIASCO Normalien GmbFI)... 

Extension of the hydrodynamic theory to explain the variation of detonation velocity with cartridge diameter takes place in two stages. First, the structure of the reaction zone is studied to allow for the fact that the chemical reaction takes place in a finite time secondly, the effect of lateral losses on these reactions is studied. A simplified case neglecting the effects of heat conduction or diffusion and of viscosity is shown in Fig. 2.5. The Rankine-Hugoniot curves for the unreacted explosive and for the detonation products are shown, together with the Raleigh line. In the reaction zone the explosive is suddenly compressed from its initial state at... 

In Germany, the test was conducted by heating an entire cartridge for 5 days at 30° (86°F). The requirement was that no NG should exude and, after cooling, that the cartridge dimensions remain unchanged Refs 1) Marshall 1 (1917), 163 2) Naoum,... 

In Germany, the test was conducted by heating an entire cartridge for 5 days at 30°... 

With the controlled atmosphere heated sample holder, it was a simple matter to connect a thermistor-type thermal conductivity cell to the system and, by means of an external multichannel recorder, record the DRS and the evolved gas detection lEGD) curves simultaneously (17). This modification of the apparatus is shown in Figure 9.4. The cell was connected to a Carle Model 1000 Micro-Detector system by means of metal and rubber tubing. The thermal conductivity cell was enclosed by an aluminum block which was heated to 100 C bv means of a cartridge heater. The block was connected to a preheat chamber, also operated at 100 C, which was used to preheat the helium gas stream before it entered the detector. The output from the detector bridge was led into one channel of a four-channel 0-5 mV Leeds and Northrup multipoint strip-chart potentiometric recorder. The temperature programmer from a Deltatherm III DTA instrument was used to control the temperature rise of the DRS cell. Output from the Beckman Model DK-2A... 

X-ray diffraction can be used to identify the phases which are present in a catalyst. To follow the evolution of a catalyst during pretreatment or catalytic reaction (ammonia or methanol synthesis), in situ XRD experiments have been performed. For this purpose Nix et al. (1987) have built a high-pressure XRD cell operating up to 50 bar and temperatures up to 700 K. The reactant gases flow over the catalysts sample heated by conduction from a cartridge heater. The temperatures are measured and controlled using a thermocouple fixed into the copper support block (fig. 3). 

The samples were pre-calcinated at 550°C (6 h) with a heating rate of l°C.min-l in a quartz cell in a flow (200 ml.min-l) of dry N2-O2 mixture. After cooling to 100°C, the zeolite was saturated during 6 h with a dry CO2 stream (12 ml.min-1) at atmospheric pressure. A flow of dry N2 (9.8 ml.min l) filtered on a cartridge (% H2O<0.4 ppm) was then admitted. After temperature equilibration of the system, the zeolite sample was heated at a rate of 3°C /min, in steps of 50°C. At each step temperature, the catalyst was maintained during 2 h. llie desorbed CO2 was collected under a nitrogen flow in a NaOH solution thermostatized at 25°C. The amounts of evolved CO2 were determined by titration continously performed by conductimetry using a conductivity cell (Schott LF 3100 Pt, K=1.0), connected to a Consort K 320 conductimeter. 

Good temperature control over aU areas of the tool is recommended and correctly placed cartridge heaters used in conjunction with thermocouples and efficient controllers give an ideal system. Mold heating can be by any of the conventional methods, but direct conduction from platens is probably the easiest and most versatile. Conventional methods of production of heat are by oil or electricity. 

The next component in the circuit is a heating unit. When the heating unit is on, it conducts heat through the metal hardware to the polymer. The most common type of heating unit is a heater band that connects onto the outside surface of the hardware. Some dies utilize heater cartridges inserted inside a hole in the hardware. Heating units are rated by power, where the amount required is determined by the mass of metal to which the unit is attached. 

The die heating may be facilitated using electrical cartridge heaters, strip heaters or by circulating oil. Even though the main heat transfer is affected by conduction, in some cases radio frequency radiations are used. The dies are mainly fabricated of steel with their interior surfaces generally chrome plated for increased die life and improved surface finish (Meyer, 1985). 

There are two main setups for conducting PLE static and dynamic modes. In the static mode, the extraction cell is filled with the dried powdered plant material and the solvent, placed in an oven, and then heated which results in the pressure increasing in the cell. After a specified period of time, the system is flushed into the collecting vial with a pressurized nitrogen flow. Static extraction is preferred for compounds that are strongly bonded to the matrix. In the dynamic mode, a few milliliters (typically 0.5-2.0 mL min ) of fresh solvent are continuously percolated through the cartridge under pressure at a constant flow rate for a fixed period of time. Dynamic extraction is preferentially used for easily extractable compounds. ASE instruments from Dionex are currently the only commercially available systems that allow static and dynamic extractions in the same run. 

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