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Exposion heat

If a plastic product is free to expand and contract, its thermal expansion property will usually be of little significance. However, if it is attached to another material, one having a lower CLTE, then the movement of the part will be restricted. A temperature change will then result in developing thermal stresses in the part. The magnitude of these stresses will depend on the temperature change, the method of attachment and relative expansion, and the modulus characteristics of the two materials at the point of the exposed heat. [Pg.399]

Alembics and distillation pots are not necessary on mercury diffusion pumps because mercury does not fractionate like oils. Although mercury and oil diffusion pumps use the same principle to function, they differ markedly in design. Because there is no fractionating ability in mercury pumps, oils cannot be used in mercury pumps. However, mercury can be used in an oil-designed metal pump on a limited basis—albeit with a noticeable loss of performance. Never use mercury in a diffusion pump with exposed heating elements because the mercury will short out the pump. [Pg.384]

A fourth degree of freedom is consumed to control column pressure. The valves available are condenser cooling (by far the most commonly7 used), reboiler heat input, and feed (if the feed is partially vapor). If a flooded condenser is used, the cooling water valve is wide open and an additional valve, typically located between the condenser and the reflux drum, is used to cover or expose heat-transfer area in the condenser. [Pg.196]

The flat exposed heating plate is extremely dangerous when hot always check that the plate is cool by passing your hand over the plate without touching it or by placing a drop of water on the plate. If you have to pick up a hot plate, hold it by the sides and do not touch the plate it may burn. Typical uses of hot plates are illustrated in Fig. 5.12a. [Pg.34]

Hot surfaces Ducts, pipes, radiant heaters, or industrial trucks exposing heat sensitive material Provide appropriate space separation and appropriate industrial trucks MSDS NFPA 505... [Pg.28]

Heating capacity of furnaces with top and bottom firing is less than twice that of furnace with top heating only because (1) the required water-cooled supports reduce the loads exposed heat transfer area and (2) the cold supports also act as heat sinks, stealing heat from the load and from the hot furnace gases, and (3) bottom-zone heat transfer also is reduced by movement of the hot furnace gases from the bottom zone to the top zone. [Pg.153]

The second potential DBA fire scenario involved the failure of the heating element housing followed by an operator error to allow combustible material to touch the exposed heating element. Both events were required to initiate a fire in the event tree analysis. The frequencies per year for such an accident developed in the event tree analysis for both scenarios agreed with the frequency for an extraction SCB fire as assessed in the hazard evaluation. [Pg.478]

Specimens used in tests were sections of cables with PVC outer coating. PVC was plasticized with DOF softener. The materials considered were exposed to the radiation and thermal aging. The samples have been irradiated at room temperature by hard gamma rays with 10 rad/sec dose power. A number of samples had been heated for long different times at 90°C. Besides a special specimens were cut out from outer coating for test on tensile machine like "Instron". The total doses of irradiation, times of heating and elongations at break obtained with "Instron" are listed in Table 1. [Pg.244]

Diamond behaves somewhat differently in that n is low in air, about 0.1. It is dependent, however, on which crystal face is involved, and rises severalfold in vacuum (after heating) [1,2,25]. The behavior of sapphire is similar [24]. Diamond surfaces, incidentally, can have an oxide layer. Naturally occurring ones may be hydrophilic or hydrophobic, depending on whether they are found in formations exposed to air and water. The relation between surface wettability and friction seems not to have been studied. [Pg.440]

The basic assumption is that the Langmuir equation applies to each layer, with the added postulate that for the first layer the heat of adsorption Q may have some special value, whereas for all succeeding layers, it is equal to Qu, the heat of condensation of the liquid adsorbate. A furfter assumption is that evaporation and condensation can occur only from or on exposed surfaces. As illustrated in Fig. XVII-9, the picture is one of portions of uncovered surface 5o, of surface covered by a single layer 5, by a double-layer 52. and so on.f The condition for equilibrium is taken to be that the amount of each type of surface reaches a steady-state value with respect to the next-deeper one. Thus for 5o... [Pg.619]

Use approximately 0 5 ml. of glycerol, and cork the flask A securely when weighing the glycerol by difference, owing to the very hygroscopic nature of the latter. Heat on the water-bath for 60 minutes instead of 30 minutes. Excellent results are obtained by this method if a freshly opened sample of anhydrous glycerol is available a sample which has been exposed to the air for even a short period will absorb sufficient water to give inaccurate results. [Pg.452]

The steam-distillation is continued for 5 minutes after steam can first be seen entering the condenser the ideal rate of distillation is about 4 -5 ml. of distillate per minute, but this is not critical and may be varied within reasonable limits. The receiver J is then lowered from the lip K of the condenser and the steam-distillation continued for a further two minutes, thus ensuring that no traces of liquid containing ammonia are left on the inside of the condenser. At the end of this time any liquid on the lip K is rinsed with distilled water into J, which is then ready for titration. It is important that the receiver and its contents are kept cold during the distillation and it is advisable to interpose a piece of asbestos board or other screen so that it is not exposed to the heat from the burner under the steam generator. [Pg.496]

The comparatively inexpensive long-scale thermometer, widely used by students, is usually calibrated for complete immersion of the mercury column in the vapour or liquid. As generally employed for boiling point or melting point determinations, the entire column is neither surrounded by the vapour nor completely immersed in the liquid. The part of the mercury column exposed to the cooler air of the laboratory is obviously not expanded as much as the bulk of the mercury and hence the reading will be lower than the true temperature. The error thus introduced is not appreciable up to about 100°, but it may amount to 3-5° at 200° and 6-10° at 250°. The error due to the column of mercury exposed above the heating bath can be corrected by adding a stem correction, calculated by the formula ... [Pg.72]

By way of caution it should be noted that free alkali or the alkali salts of weak acids will redden the reagent like an aldehyde. It is also, of course, reddened by heat or when exposed in small quantities to the air for some time. Mineral acit greatly reduce the sensitivity of the test. [Pg.331]

When exposed to sunlight or when heated in its own vapor to 250oC, it is converted to the red variety, which does not phosphoresce in air as does the white variety. This form does not ignite... [Pg.36]

The state of the surface is now best considered in terms of distribution of site energies, each of the minima of the kind indicated in Fig. 1.7 being regarded as an adsorption site. The distribution function is defined as the number of sites for which the interaction potential lies between and (rpo + d o)> various forms of this function have been proposed from time to time. One might expect the form ofto fio derivable from measurements of the change in the heat of adsorption with the amount adsorbed. In practice the situation is complicated by the interaction of the adsorbed molecules with each other to an extent depending on their mean distance of separation, and also by the fact that the exact proportion of the different crystal faces exposed is usually unknown. It is rarely possible, therefore, to formulate the distribution function for a given solid except very approximately. [Pg.20]

The effect of these factors on the adsorption isotherm may be elucidated by reference to specific examples. In the case of the isotherm of Fig. 5.17(a), the nonporous silica had not been re-heated after preparation, but had been exposed to near-saturated water vapour to ensure complete hydroxylation. The isotherm is of Type II and is completely reversible. On the sample outgassed at 1000°C (Fig. 5.17(h)) the isotherm is quite different the adsorption branch is very close to Type III, and there is extrensive hysteresis extending over the whole isotherm, with considerable retention of adsorbate on outgassing at 25°C at the end of the run. [Pg.272]


See other pages where Exposion heat is mentioned: [Pg.384]    [Pg.168]    [Pg.15]    [Pg.257]    [Pg.123]    [Pg.189]    [Pg.378]    [Pg.28]    [Pg.27]    [Pg.202]    [Pg.291]    [Pg.367]    [Pg.384]    [Pg.168]    [Pg.15]    [Pg.257]    [Pg.123]    [Pg.189]    [Pg.378]    [Pg.28]    [Pg.27]    [Pg.202]    [Pg.291]    [Pg.367]    [Pg.426]    [Pg.304]    [Pg.942]    [Pg.1895]    [Pg.186]    [Pg.5]    [Pg.36]    [Pg.480]    [Pg.72]    [Pg.93]    [Pg.222]    [Pg.445]    [Pg.769]    [Pg.775]    [Pg.922]    [Pg.986]    [Pg.15]    [Pg.144]    [Pg.279]   


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