Temperature inside oven

Figure 7.4 Schematic diagram of a gas chromatography (GC) system. The carrier gas enters from the left, and the sample is injected into the gas flow and is carried through the capillary column inside a temperature-controlled oven where the components are separated. Detection here is by flame ionization, where the eluent increases the conductivity of the flame.

ISO 4577 1983 Plastics - Polypropylene and propylene-copolymers - Determination of thermal oxidative stability in air - Oven method ISO 7279 1984 Polypropylene (PP) fittings for pipes under pressure - Sockets for fusion using heated tools - Metric series - Dimensions of sockets ISO 7671 2003 Plastics piping systems for soil and waste discharge (low and high temperature) inside buildings - Polypropylene (PP)... 

It was discussed above that two types of factors can influence our process or system controlled factors design factors in Taguchi s terminology) and uncontrolled factors noise factors. The latter are inherent to the experimentation and can only be estimated by replication of runs. If the variability between replications is too large, any conclusion drawn from our study may have no meaning at all. Further, their variability can be as important as the mean of the replicates. Noise factors must be identified properly and, if possible, simulated in our experimentation. Sometimes noise factors are actually uncontrolled and, in such a case, we must be able to simulate them by means of some alternative parameter controlled during the experiments. For instance, temperature inside an oven can be a noise factor, but we can measure it at different locations, and accordingly, the effect of temperature inside is simulated by a location factor. 

Air circulation in typical ovens is by convection, and the temperature inside the oven is usually nonuniform. To obtain better temperature uniformity and improved control, a lining made of thick sheet aluminum or copper can be installed. 

The high temperature inside an oven speeds up the chemical reactions that turn a liquid cake batter into a more solid, spongy cake. This works the other way, too. Lowering the temperature slows down most reactions. If you set the oven temperature too low, your cake will not bake properly. 

To characterize the sensors, they were placed inside a measurement chamber, which was itself mounted in a temperature-controlled oven (Fig. 3). The atmosphere in the measurement chamber could be controlled via gas-mixing equipment involving mass-flow controllers. The chamber was first heated up to 270 °C in a nitrogen (Nj) atmosphere. When the steady state was reached, selected amounts of propane, propene and water were added to the nitrogen carrier gas. The overall gas-flow was held constant at 500 cmVmin. The analytes were prethinned to 800 ppm in nitrogen carrier gas. A bubbler was used for the humidification of the gas. 

In this test (Figure 3.3) the sample is held in a glass liner within a stainless steel pressure vessel, in turn inside a temperature-programmed oven. The pressure vessel has a bleed valve for venting decomposition products and a bursting disc, rated at 67 bar (l(X)0 psi). A remote pressure transducer is linked to the vessel by a steel capillary. The oven is heated at a fixed rate over the experimental temperature range, and a chart records the sample temperature and vessel internal pressure as functions of time. 

Two core plugs from a carbonate reservoir (calcite) were used [68]. One core holder held a high permeability core (initial brine permeability = 535 mD) and the second core holder had a low permeability core (initial brine permeability = 3.1 mD). The cores and floating-piston eeUs were placed inside a temperature-controlled oven. Foam quality was varied by adjusting the flow rates of nitrogen and the snrfactant solution while keeping the total flow rate at 5 cm /min. 

A fully automated batch fractionation instrument called mc2-PREP is now available. Figure 10 shows a schematic of mc2-PREP. The two stirred fractionation vessels placed inside a temperature-programmable oven can fractionate polymers into eight fractions by either solvent/nonsolvent or temperatin-e variation techniques. Operator intervention is only required to precipitate and filter the polymer fractions after they are isolated from the parent polymer solution. 

Figure 26 shows a schematic diagram of one Crystaf crystallization vessel. The commercial version of Crystaf (Polymer C/zar, Spain) has five crystallization vessels that are placed inside a temperature-programmable oven. The vessels can be used in parallel to analyze up to five samples simultaneously (Fig. 27). The vessels are made of stainless steel and are provided with stirring units. The crystallization vessels are connected to a nitrogen line, a waste line, and a sampling line attached to an in-line filter. The sampling lines are connected...

Polyacetylene is very sensitive to oxygen, and we have therefore taken steps to ensure that, where possible, fabrication is performed in an oxygen-free environment. We perform all fabrication steps involving the polyacetylene inside a glove-box which is maintained with oxygen and water levels of less than 5 ppm. The glove box contains, therefore, the spin-coater, temperature-controlled ovens, and tiie metals evaporator (though for some of the earlier work on the Schottky diode structures, the sample was transfened rapidly in air to a metal evaporator, and pumped for 12 hours prior to evaporation of the top contact). 

Annealing inside oven The extruded 30%-PCL and 50%-PCL fibers were cut into cylinders of 4 mm long and annealed in a conventional oven at 80°C, above the melting temperatures of PCL and PEO. Time periods of 3, 6, 10 and 15 min were used for the annealing process. The temperature inside the oven was allowed to attain equiUbrium before annealing the sample. The annealed samples were rapidly cooled to room temperature and soaked in tap water. After 96 hours, the samples were taken out of the water bath and dried at room temperature for 24 hours. The PEO in the circular fiber dissolves in water, resulting in a porous PCL fiber. 

We can sample the energy density of radiation p(v, T) within a chamber at a fixed temperature T (essentially an oven or furnace) by opening a tiny transparent window in the chamber wall so as to let a little radiation out. The amount of radiation sampled must be very small so as not to disturb the equilibrium condition inside the chamber. When this is done at many different frequencies v, the blackbody spectrum is obtained. When the temperature is changed, the area under the spechal curve is greater or smaller and the curve is displaced on the frequency axis but its shape remains essentially the same. The chamber is called a blackbody because, from the point of view of an observer within the chamber, radiation lost through the aperture to the universe is perfectly absorbed the probability of a photon finding its way from the universe back through the aperture into the chamber is zero. 

As noted earlier, control of the column s temperature is critical to attaining a good separation in gas chromatography. For this reason the column is located inside a thermostated oven. In an isothermal separation the column is maintained at a constant temperature, the choice of which is dictated by the solutes. Normally, the tern-... 

Where substances are sufficiently stable, removal of solvent from recrystallised materials presents no problems. The crystals, after filtering at the pump (and perhaps air-drying by suction), are heated in an oven above the boiling point of the solvent (but below this melting point of the crystals), followed by cooling in a desiccator. Where this treatment is inadvisable, it is still often possible to heat to a lower temperature under reduced pressure, for example in an Abderhalden pistol. This device consists of a small chamber which is heated externally by the vapour of a boiling solvent. Inside this chamber, which can be evacuated by a water pump or some other vacuum pump, is... 

Fig. 4.61 illustrates that the mould temperature is quite different from the set oven temperature (330°C) or indeed the actual oven temperature, throughout the moulding cycle. An even more important observation is that in order to control the rotational moulding process it is desirable to monitor the temperature of the air inside the mould. This is possible because there is normally a vent tube through the mould wall in order to ensure equal pressures inside and outside the mould. This vent tube provides an easy access for a thermocouple to measure the internal air temperature. 

Dry heat sterilization is usually carried out in a hot air oven which comprises an insulated polished stainless steel chamber, with a usual capacity of up to 250 litres, surrounded by an outer case containing electric heaters located in positions to prevent cool spots developing inside the chamber. A fan is fitted to the rear of the oven to provide circulating air, thus ensuring more rapid equilibration of temperature. Shelves within the chamber are perforated to allow good air flow. Thermocouples can be used to monitor the temperature of both the oven air and articles contained within. A fixed temperature sensor connected to a chart recorder provides a permanent record of the sterilization cycle. Appropriate door-locking controls should be incorporated to prevent interruption of a sterilization cycle once begun. 

Figure 4.20. Experimental set-ups for temperature programmed reduction, oxidation and desorption. Upper left The reactor is inside the oven, the temperature of which can be increased linearly with time. Gas consumption by the catalyst is monitored by the change in thermal conductivity of the gas mixture it is essential to remove traces of water, etc. because these would affect the thermal conductivity measurement. Lower-left ...

High-temperature/low-pressure inorganic digestions are an area of application that has benefited from recent advances in vessel and sensor design. The inert properties of Teflon and its resistance to acid attack make it the material of choice for microwave pressure-vessel construction. Improved commercial systems offer additional safety precautions and improved facilities for pressure and/or temperature control. Also, the distribution of microwave radiation inside the oven cavity is fairly homogeneous. Low-pressure systems allow decomposition temperatures of about 180 °C. However, for many matrices, such temperatures are not sufficient to guarantee the complete ashing of thermoresistant sample components. 

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