RISE RATE

Viscosity can also be determined from the rising rate of an air bubble through a Hquid. This simple technique is widely used for routine viscosity measurements of Newtonian fluids. A bubble tube viscometer consists of a glass tube of a certain size to which Hquid is added until a small air space remains at the top. The tube is then capped. When it is inverted, the air bubble rises through the Hquid. The rise time in seconds may be taken as a measure of viscosity, or an approximate viscosity in mm /s may be calculated from it. In an older method that is commonly used, the rate of rise is matched to that of a member of a series of standards, eg, with that of the Gardner-Holdt bubble tubes. Unfortunately, this technique employs a nonlinear scale of letter designations and may be difficult to interpret. 

Black Liquor Soap Recovery. Black Hquor soap consists of the sodium salts of the resin and fatty acids with small amounts of unsaponifiables. The soap is most easily separated from the black Hquor by skimming at an intermediate stage, when the black Hquor is evaporated to 25% soHds (7). At this soHds level, the soap rises in the skimmer at a rate of 0.76 m/h. At higher soHds concentrations, the tall oil soap is less soluble, but higher viscosity lowers the soap rise rate and increases the necessary residence times in the soap skimmer beyond 3—4 hours. The time required for soap recovery can be reduced by installing baffles, by the use of chemical flocculants (8,9), and by air injection into the suction side of the soap skimmer feed pump. Soap density is controUed by the rate of air injection. Optimum results (70% skimmer efficiency) are obtained at a soap density of 0.84 kg/L (7 lb/gal). This soap has a minimum residual black Hquor content of 15% (10—12). 

The kinetic comparison of amination of the chloropyridines is incomplete due to the intervention of acid catalysis. The reaction of 2-chloropyridine with piperidine shows a constant rate coefficient as the reaction proceeds to completion, but, with the less basic morpholine, a rising coefficient indicative of acid catalysis is observed. 4-Chloropyridine exhibits a rising rate coefficient even with piperidine. ... 

Rise Rate Fall Rate Maximum Quantum... 

In addition to the extra hardware required for these experimental runs, the ARC was operated differently than under standard hazard evaluation conditions. Instead of heating, searching and waiting, the samples were heated to a specified temperature and were then maintained isothermally at that temperature for extended periods of time. Pressure and temperature data were then monitored and stored in the microcomputer at a rate of 1 Hz. It should be noted that the apparatus reverts back to normal operation (i.e., tracking an exotherm), if a heat rise rate greater than 0.02 °C/min is detected. 

Consequence of runaway reaction Temperature rise rates Gas evolution rates Adiabatic Dewar Adiabatic calorimetry Pressure ARC VSP/RSST RC1 pressure vessel... 

If not, what are the important characteristics of the thermal decomposition if it should occur, such as time to onset, enthalpy of decomposition, self-heat rate, rate of pressure rise, rate of temperature rise, moles of gas/mole of substance and... 

Experimental data can be obtained from the DSC and from reaction calorimeters for the conditions of the desired reactions, and from the DSC, the ARC, the Reactive System Screening Test (RSST—Fauske and Associates) and from the Vent Size Package (VSP) for conditions allowing undesired reactions. The pressure effect can be studied using the ARC or DIERS methods. From the results of these tests, the rate of temperature rise and the maximum acceptable conditions for specific equipment can be calculated. The same holds for the pressure rise rate. 

The lower explosive limit and minimum explosive concentrations of flax, wool, cotton, jute, hemp and sisal fibres are of the same order of magnitude as those of highly explosive dusts [15], The explosibility of pyrites dusts with sulfur contents above 20% was evaluated experimentally. Dusts of 30% sulfur content gave explosion pressures of 3 bar at pressure rise rates of 16 bar/sec. Mixtures of 60% pyrites and 40% powdered limestone still showed significant pressure effects, and the proportion of limestone actually needed to suppress explosions was considerably above the values currently accepted by mining industries [16], Effects of mixtures of particle sizes in combustible dusts upon minimum ignition temperature (T ") and upon presence or absence of explosion were studied. Presence of 30% of fines in a coarse dust lowers Tf significantly [17], Experimental explosions of polyethylene,... 

Figure I. Action Potentials from crayfish giant axons. Control = Top Trace. Toxin (0.8 ug/ml) reduced rise rate and amplitude after 3, 10, 15, 20, and 25 min.

MPa/ms pressure rise rate in closed bomb... 

A model for bubble rise rate within a liquid, used by DIERS as - the basis for their level swell methodology. See Annex 3. 

The skimming units are divided into parallel channels and designed so that an oil droplet 150 g. or larger will be separated from the water. Droplet size is based on the oil droplet rise rate being equal to or greater than the overflow rate (Overflow rate = throughput t effective surface area.)... 

Od/water separation is enhanced because both the particle size and density difference have been increased The net result is a higher velocity rise rate for the froth which is continuously removed from the surface of the water by a skimmer arm. 

In Figure 5, the low temperature weight loss rates for several heat-up runs are shown as functions of the extent of weight loss. The range of operating conditions includes l5°-35°F/min temperature rise rates and 20-500 psig pressures. In all cases, the low temperature rate can be... 

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