CHLORINE-CONTAINING SYSTEMS

Dokter, T., Explosion hazards of methyl chloride and chlorine-containing systems, PhD thesis, Twente University, Netherlands. 1987... 

The fire and explosion hazards of chlorine-containing systems have been reviewed [1,3]. A rail tanker of chlorine was being emptied to a chlorine gas distribution network... 

See Hydrogen, below Steel, below See CHLORINE-CONTAINING SYSTEMS See also REPAIR AND MAINTENANCE See other IGNITION sources... 

Chemical plant safety, 68 Chemical stability/reactivity assessment, 68 Chemical vapour deposition (cvd), 69 Chlorinated paraffins, 69 N-chlorinated phosphorus amides, 69 Chlorinated poly(dimethylsiloxanes), 69 Chlorinated rubber, 69 Chlorine-containing systems, 70 Chlorite salts, 70 Chlorofluorocarbons, 71 N-Chloronitroamines, 71 Chlorophyll, 71... 

Chlorins, as reported by Cubeddn et al, show photophysical properties similar to those of the porphyrin systems, but have enhanced and red-shifted Q bands ( 670 nm) which make chlorin-containing systems better candidates for PDT. Chlorophyll a 15, the green photosynthetic pigment, is one prototype of the chlorin class of natural products. It or its derivatives can be extracted from certain Spirulina species without any contamination with chlorophyll thus... 

Because of the different vulcanization chemistry involved in each commercial ACM, a vulcanization system specific to the cure site present has to be adopted. Many cure systems for labile chlorine containing ACM have been proposed (45). Among these the alkali metal carboxylate—sulfur cure system, or soap—sulfur as it is called in the United States, became the mainstay of acryflc elastomer technology in the early 1960s (46), and continues to be widely used. 

New efficient vulcanization systems have been introduced in the market based on quaternary ammonium salts initially developed in Italy (29—33) and later adopted in Japan (34) to vulcanize epoxy/carboxyl cure sites. They have been found effective in chlorine containing ACM dual cure site with carboxyl monomer (43). This accelerator system together with a retarder (or scorch inhibitor) based on stearic acid (43) and/or guanidine (29—33) can eliminate post-curing. More recently (47,48), in the United States a proprietary vulcanization package based on zinc diethyldithiocarbamate [14324-55-1]... 

The self-extinguishing characteristics of the chlorine-containing resins are improved by incorporation of antimony oxide but this approach is not possible where translucent sheet is required. As an alternative to chlorine-based systems a number of bromine-containing resins have been prepared and, whilst claimed to be more effective, are not currently widely used. It is probably true to say that fire-retarding additives are used more commonly than polymers containing halogen groupings. 

Figure 3.4. A chlorine storage system with collection sump with vapor containment (Puglionesi and Craig, 1991)-...

The instability of DAST-type brighteners towards chlorine-containing bleaches has been mentioned already. They also show limited stability towards per-acids. As recommended washing temperatures have tended to fall in recent years, a bleach consisting of sodium perborate activated by addition of tetra-acetylethylenediamine (11.63) has become an important component of household detergent formulations. This system is effective at temperatures as low as 40-50 °C. Since the FBA may be sensitive to the activated oxidant, however, in some formulations it is necessary to protect compounds such as 11.60 or 11.61 by encapsulating either the brightener or the activator, if adequate shelf-life is to be maintained. 

Partial what-if analyses for the two example processes described in Section 4.0 are shown in Tables 4.9 and 4.10. Although for actual, more complex analyses, the what-if tables for each line or vessel would be separate, for these examples, a single table was developed. A preliminary hazard analysis (PHA) would identify that the intrinsic hazards associated with HF are its reactivity (including reactivity with water, by solution), corrosivity (including carbon steel, if wet), toxicity via inhalation and skin contact, and environmental toxicity. The N2 supply system pressure is not considered in this example. The specific effects of loss of containment could be explicitly stated in the "loss of HF containment" scenarios identified. Similarly, the effects of loss of chlorine containment, including the reactivity and toxicity of chlorine, could be specified for the second example. 

From the metal loss determinations it was possible to construct the mean corrosion rate - time curves for the acrylic and vinyl-acrylic systems. From Figure 6 it is clear that an initial interface metal loss process in the chlorine-containing vinyl-acrylic system quickly arrests within 12 days exposure, and the overall metal loss at 50 days is only of the order of 0.75 micron. The acrylic system shows no such arrest and indeed the corrosion rate increases with time to destruction of the foil. 

The low metal loss figures for the chlorine containing vinyl acrylic system noted above were supported by analytical measurements of iron pick-up in coatings on grit blasted Q panels. Under constant immersion in 3J NaCl the iron pick-up, equivalent to 0.13 micron metal loss, remained virtually unchanged after 14 days over the 63 days exposure. However, the acrylic system had an equivalent metal loss of 0.55 micron at 14 days which increased steadily to 1.43 microns at 63 days. 

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