Decomposition pressure test

These tests include differential scanning calorimetry (DSC) and various forms of differential thermal analysis (DTA) the insulated exotherm test (IET), decomposition pressure test (DPT), and the Carius (or ICI) sealed tube test. Commercial variants of these tests are available. 

Decision making, process risk management decisions, documentation, 105-106 Decision point, chemical reactivity tests, 90 Decommissioning, chemical reactivity hazard management, 25 Decomposition pressure test, chemical reactivity tests, 88... 

The insulated exotheim test is carried out in containers which are not completely sealed, and some volatile material may be lost. Where this is a problem or where data is needed on gas generation rates and pressurization characteristics in the late stages of thermal decomposition, the decomposition pressure test (DPT) 2 can be used. 

Output to amplifier Figure 3.3 Decomposition pressure test. 

DATA FROM THE DECOMPOSITION PRESSURE TEST The output from the decomposition pressure test (DPT) is a plot of pressure against time which can be used to determine the volume of gas evolved during a decomposition xhg volume of gas evolved is calculated assuming that at all end states the gas enclosed within the test vessel is ideal, that is ... 

A typical analogue trace from the decomposition pressure test on tert-butyl peroxybenzoate is shown in Figure 4.9. The data can be analysed as follows ... 

Figure 4.9 Analogue data trace for decomposition pressure test.

The volume of gas generated during the observed reaction can be determined from the pressure data, using a similar analysis to that for the decomposition pressure test (see Section 4.3.4, page 58). 

Some other results of other TPH experiments can be seen in Table 1. In atmospheric-pressure tests at 900°C with 500 ppm HjS in the gas phase, sulfur was not desorbed from Catalyst Al. The same phenomenon was noticed in the tests performed at 900°C under 5 bar pressure with Catalysts A2 and C. In addition, when the sulfur content of the catalyst beds was analyzed after TPH experiments, it was observed that only a small amount of sulfur was present on the catalyst. This observation indicates that sulfur adsorption is not completely reversible, but that part of the adsorbed sulfur remains on the catalyst. The effect of this phenomenon was also observed when a catalyst was regenerated by removal of HjS to the gas mixture in fixed-bed poisoning tests. The catalyst activity did not reach the original level (with no HjS in the gas) especially in ammonia decomposition. The analysis of the sulfur content of the bed showed that a small amount of sulfur was still present on the catalyst. 

Analytical and Test Methods. o-Nitrotoluene can be analyzed for purity and isomer content by infrared spectroscopy with an accuracy of about 1%. -Nitrotoluene content can be estimated by the decomposition of the isomeric toluene diazonium chlorides because the ortho and meta isomers decompose more readily than the para isomer. A colorimetric method for determining the content of the various isomers is based on the color which forms when the mononitrotoluenes are dissolved in sulfuric acid (45). From the absorption of the sulfuric acid solution at 436 and 305 nm, the ortho and para isomer content can be deterrnined, and the meta isomer can be obtained by difference. However, this and other colorimetric methods are subject to possible interferences from other aromatic nitro compounds. A titrimetric method, based on the reduction of the nitro group with titanium(III) sulfate or chloride, can be used to determine mononitrotoluenes (32). Chromatographic methods, eg, gas chromatography or high pressure Hquid chromatography, are well suited for the deterrnination of mononitrotoluenes as well as its individual isomers. Freezing points are used commonly as indicators of purity of the various isomers. 

Adiabatic calorimetry. Dewar tests are carried out at atmospheric and elevated pressure. Sealed ampoules, Dewars with mixing, isothermal calorimeters, etc. can be used. Temperature and pressure are measured as a function of time. From these data rates of temperature and pressure rises as well as the adiabatic temperature ri.se may be determined. If the log p versus UT graph is a straight line, this is likely to be the vapour pressure. If the graph is curved, decomposition reactions should be considered. Typical temperature-time curves obtained from Dewar flask experiments are shown in Fig. 5.4-60. The adiabatic induction time can be evaluated as a function of the initial temperature and as a function of the temperature at which the induction time, tmi, exceeds a specified value. 

Confinement volume plays a huge role but cannot be modelled. The solidity of the closure does not perform any role. So a sheet of paper placed on the test tube is enough to transform the deflagration decomposition process of benzoyl peroxide into a detonation, which pulverises the test tube (this accident happened to the author but proved to be unrepeatable during a later test). So it is not a transition -al effect of pressure increase that plays an aggravating roie. 

As microwave sample preparation has evolved, standard microwave procedures have been developed and approved by numerous standard methods organisations (ASTM, AOAC International, EPA, etc.), see ref. [64]. Examples are standard test methods for carbon black/ash content (ASTM Method D 1506-97), lead analysis in direct paint samples (ASTM Method E 1645-94), etc. Table 8.15 shows some microwave ashing references (detection weight). A French AFNOR method utilises the atmospheric pressure single-mode microwave method as an alternative sample preparation procedure for Kjeldahl nitrogen determination [84], The performance of a microwave-assisted decomposition for rapid determination of glass fibre content in plastics for QC has been described [85]. 

It is extremely shock-sensitive, a 4.0 kg cm shock causing detonation in 50% of test runs (cf. 3.5 kg cm for propargyl bromide 2.0 kg cm for glyceryl nitrate). The intermediate bis-chlorosulfite involved in the preparation needs low temperatures to avoid vigorous decomposition. The corresponding diiodo derivative was expected to be similarly hazardous [1], and this has been confirmed [2]. Improvements in preparative techniques (use of dichloromethane solvent at —30°C) to avoid violent reaction have also been described [3], An attempt to distill the compound (b.p. 55-58°C/0.6 mbar, equivalent to about 230°C/l bar) at atmospheric pressure from a heating mantle led to a violent explosion [4], The compound involved was erroneously given as l,6-dichloro-2,4-hexadiene [5],... 

There is a high rate of pressure increase dining exothermic decomposition [ 1]. Energy of decomposition (in range 240-440°C) measured as 1.58 kJ/g by DSC, and Tait24 was determined as 185°C by adiabatic Dewar tests, with an apparent energy of activation of 117 kJ/mol [2],... 

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