Time-temperature curves for

Complicated problems of transient heat flow can be resolved by computer. Typical time-temperature curves for non-steady cooling are shown in Figures 16.1 and 16.2, and the subject is met again in Section 26.2. 

Time-temperature curves for fire resistance for different types of materials are available from American Society for Testing and Materials (ASTM) Standard E 119 (Ref. 41). 

Brenden and Chamberlain (6) measured heat release rate from wall assemblies having fire-retardant-treated studs and gypsum board as interior finish in the FPL fire endurance furnace using three methods (a) the substitution method, by which the amount of fuel required to maintain the ASTM E-119 time-temperature curve for a... 

Time Temperature Curves for Petroleum versus Cellulosic Fires... 

Figure 5-17. Time-Temperature Curve for Fire Tests...

Fig. 12 Time-torque curves for master batch preparations with XNBR and organoclay in the internal mixture at 160°C and 50 rpm rotor speed (a). Time-temperature curves for master batch preparations with XNBR and organoclay in the internal mixture at 160°C and 50 rpm rotor speed (b)...

Figure 9.2 Time-temperature curves for the destruction of M. tuberculosis (...), inactivation...

Fig. 33.—Time-temperature curves for wheat starch-water systems heated to 85°C by micro-waves (from Ref. 286).

Fig. 5. Reconstructed time-temperature curves for the Brent Group in the Oseberg field, and timing of oil emplacement. After Dahl Yiikler (1991) and Walderhaug (1994).

Figure 4.6-2 Experimental and calculated time-temperature curves for high-carbon run for two points within the particle ( = 0 and = 0.673). Bulk phase temperature 518°C. Initial particle temperature. (from Wang and Wen [17]).

Fig. 2 Time-temperature curves for discontinuous and continuous kneading...

Kodak D-19 solution is recommended for most spectroscopic plates and films. It can be obtained in package form or can be prepared from the data given in Table 6-1. It provides good contrast, has a low tendency to fogging, and stores well. It is best to always use fresh developer. Old or used developer requires more developing time and the possibility of fogging is increased. Recommended development time is available for various combinations of developers and spectral emulsions, and for uniformity of development, the time and temperature of development should be carefully controlled. A development temperature of 68°F usually is recommended. A time-temperature curve for D-19 developer, centered on 68°F, is given in... 

Fig. 3,105 Standard time-temperature curve for testing building constructions according to...

Figure 16.3 Time temperature curves for hydrocarbon versus cellulosic fires.

Figure 5.240 Time-temperature curves for 50% loss in strain in various HNBR elastomers (all 36% AN, IV = iodine number) compared with NBR, CSM, and CR [796]...

FIGURE 5.9 A typical time-temperature curve for forming a glass-ceramic. 

Fig. 23.5. Schematic of the time-temperature equivalence for the modulus. Every point on the curve for temperature T, lies at the same distance, log (07), to the left of that for temperature Tq.

In the case of polymer molecules where the dipoles are not directly attached to the main chain, segmental movement of the chain is not essential for dipole polarisation and dipole movement is possible at temperatures below the glass transition temperature. Such materials are less effective as electrical insulators at temperatures in the glassy range. With many of these polymers, e.g., poly(methyl methacrylate), there are two or more maxima in the power factor-temperature curve for a given frequency. The presence of two such maxima is due to the different orientation times of the dipoles with and without associated segmental motion of the main chain. 

Commercial propane and butane often contain substantial proportions of the corresponding unsaturated analogues and smaller amounts of near-related hydrocarbons, as well as these hydrocarbons themselves. Figure 20.1 shows vapor pressure/temperature curves for commercial propane and commercial butane. Due to its lower boiling point, higher rates of vaporization for substantial periods are obtainable from propane than from butane, and at the same time, appreciable pressures are maintained even at low ambient temperatures. 

A common interpretation of the runaway stage is when both the first and second derivatives of the average time-temperature curve are positive. However, because we had an external heat source in our tests, we had to account for the external heater temperature "T ". 

The FPL vertical wall furnace used in our study was described in some detail by Brenden and Chamberlain (6). This furnace is normally used to evaluate the fire endurance of wall assemblies. The basic guidelines for the furnace test method are given in the ASTM E-119 standard (5). The method was designed to evaluate the ability of a structure to withstand a standard fire exposure that simulates a fully developed fire. The furnace is gas fired, and its temperature is controlled to follow a standard time-temperature curve. A load may be applied to the assembly. The failure criterion can be taken as time at burnthrough, structural failure, or a specified temperature rise on the unexposed side of the wall—whichever comes first. The construction of the furnace is not specified in the ASTM E-119 standard. 

Calibration Test. Before the wall tests were carried out, a calibration test was conducted to evaluate burner performance and to check for agreement between fuel gas and heat release calculations. For this test, the furnace was closed with a masonry wall lined with a layer of ceramic blanket material. The ASTM E-119 time-temperature curve was followed for 60 min. 

The technique and apparatus used in this work have been described in detail [81]. The reaction vessel was made hydrophobic by exposure to the vapour of trimethylchlorosilane and evacuated for several hours. Then isobutene, dried by sodium, and methylene dichloride, stored over calcium hydride, were distilled into it, the temperature adjusted, and the reaction started by the breaking of a phial containing a solution of titanium tetrachloride in methylene dichloride and one containing water. These could be broken in this, or the reverse, order, or simultaneously. The ensuing reaction was registered as a time-temperature curve by an automatic recorder. The range of conditions studied was [C4H8] = 0.05 -0.6 mole/1, [TiClJ = (0.1-5) x 10 3 mole/1, [H20] = (0.05-5) x 10 4 mole/1, T= 18°- -95°. 

Fire resistance rating—The time period that a specific fireproofing design will protect structural supports for equipment, piping and so forth from collapse, when exposed to a fire of specified intensity. The fire intensity is usually represented by a time-temperature curve. 

Such a temperature-time-conductance curve for a vacuum-sintered sample is shown in Fig. 5. A sample, pretreated at 100°C as described above, was heated to 125°C at time zero. The conductance changes as a function of time were followed for 160 minutes (point B), and then the temperature was suddenly raised to 150°C. The time-dependent conductance changes proved to be quite reversible, contrary to the irreversible decrease of conductance with increasing temperature for samples kept in an oxygen atmosphere. 

For the third classification, known as slow burning , the exposure is 20 minutes following the standard time-temperature curve (3). No flame from the specimen may reach the angle frame at any point, and all flaming must cease within 5 minutes after the test flame is discontinued. If a material fails to meet these test requirements, it is rated as combustible. For all classifications, there are restrictions as to the amount of material which may fall from the test panel during the exposure period. 

For typical oxygen pressures, the transition from passive to active oxidation occurs at around 600-750 °C surface temperature. Curves for oxygen uptake vs. time display a transition from a simple Langmuir-Hinshelwood (LH) form for passive oxidation, to a more slowly increasing but sigmoidal form (reflecting autocatalytic aspects to the oxide island formation process) for active oxidation. 

---