Isokinetic method

Determination of hydrogen halide and halogen emissions from stationary sources—isokinetic method Determination of vapor tightness of gasoline delivery tank using pressure-vacuum test Certification and auditing of wood heaters... 

Isokinetic Methods and Integration with Very Large Timestep... 

Molecular sampling using Langevin dynamics and other methods involves integration over the infinite cylinder. The power of the isokinetic method is... 

Source sampling of particulates requites isokinetic removal of a composite sample from the stack or vent effluent to determine representative emission rates. Samples are coUected either extractively or using an in-stack filter EPA Method 5 is representative of extractive sampling, EPA Method 17 of in-stack filtration. Other means of source sampling have been used, but they have been largely supplanted by EPA methods. Continuous in-stack monitors of opacity utilize attenuation of radiation across the effluent. Opacity measurements are affected by the particle size, shape, size distribution, refractive index, and the wavelength of the radiation (25,26). 

Obviously for this method to work the ratio T1IT2 must be appreciably smaller than unity. Provided this condition is met, this method is a simple and reliable way to test for an isokinetic relationship or to detect deviations from such a relationship. Exner shows examples of systems plotted both as log 2 vs. log and as AH vs. A5, demonstrating the inadequacy of the latter plot. Exner has also developed a statistical analysis of the Petersen method this analysis yields p and an uncertainty estimate of p. Exner has applied his statistical methods to 100 reaction series, finding that 78 of them follow approximately valid isokinetic relationships. 

Earlier analyses making use of AH vs. AS plots generated many p values in the experimentally accessible range, and at least some of these are probably artifacts resulting from the error correlation in this type of plot. Exner s treatment yields p values that may be positive or negative and that are often experimentally inaccessible. Some authors have associated isokinetic relationships and p values with specific chemical phenomena, particularly solvation effects and solvent structure, but skepticism seems justified in view of the treatments of Exner and Krug et al. At the present time an isokinetic relationship should not be claimed solely on the basis of a plot of AH vs. A5, but should be examined by the Exner or Krug methods. 

Induced reactions, 102 Induction period, 72 Inhibitor competitive, 92 noncompetitive, 93 Initial rates, method of, 8, 32 from power series, 8 Initiation step, 182 Inverse dependences, 130-131 Isokinetic relationship, 164—165 Isokinetic temperature, 163, 238 Isolation, method of (see Flooding, method of)... 

The last method for illustrating an isokinetic relationship is based on the dependence on a parameter. If both AH and AS are related to the parameter then by its elimination from the two equations, the relation between AH and... 

The method outlined is quick and useful for testing isokinetic relationships described in the literature and for finding approximate values of j3 (149). It should replace the incorrect plotting of E versus log A, which gives fallacious results for the value of (3 and which usually simulates better correlations than in fact apply. Particularly, the values of correlation coefficients (1) in the E versus log A plane are meaningless. As shown objectively in Figures 9-12, the failure of this plotting is not caused by experimental errors only (3, 143, 153), nor is it confined to values of j5 near the error slope or within the interval of experimental temperatures (151). 

Ritchie and Sager (124) distinguish three types of reaction series according to whether the Hammett equation or the isokinetic relationship is obeyed, or both. The result that the former can be commonly valid without the latter seems to be based on previous incorrect statistical methods and contradicts the theoretical conclusions. Probably both equations are much more frequently valid together than was anticipated. The last case, when the isokinetic relationship holds and the Hammett equation does not, may be quite common, of course, and has a clear meaning. Such a series meets the condition for an extrathermo-dynamic treatment when enough experimental material accumulates, it is only necessary to define a new kind of substituent constant. 

In order to characterize the concentration of dust flowing inside a duct, a measured amount of dust must be extracted over a known period of time. This collection velocity must be the same as the internal duct flow velocity to avoid altering the distribution of dust particle sizes. In addition, a number of sample points over the entire duct cross sectional area is necessary to define the overall dust concentration. This method of sampling, known as gravimetric sampling under isokinetic conditions, was used to determine the dust concentrations at the various manufacturing areas in the Army Ammunition Plants. 

From the data listed in Tables I-V, we conclude that most authors would probably accept that there is evidence for the existence of a compensation relation when ae < O.le in measurements extending over AE 100 and when isokinetic temperature / , would appear to be the most useful criterion for assessing the excellence of fit of Arrhenius values to Eq. (2). The value of oL, a measure of the scatter of data about the line, must always be considered with reference to the distribution of data about that line and the range AE. As the scatter of results is reduced and the range AE is extended, the values of a dimin i, and for the most satisfactory examples of compensation behavior that we have found ae < 0.03e. There remains, however, the basic requirement for the advancement of the subject that a more rigorous method of statistical analysis must be developed for treatment of kinetic data. In addition, uniform and accepted criteria are required to judge quantitatively the accuracy of obedience of results to Eq. (2) or, indeed, any other relationship. 

Air Sampling The relative cleanliness of air in the most critical environment is assessed using passive sampling systems such as settle plates or estimated volumetri-cally using active air samplers. Active air samplers should be designed to be isokinetic in operation to avoid disruptions to unidirectional airflow. Considerable variability has been reported among the several sampling methods employed for... 

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