Incompatible chemicals

The third characteristic of interest grows directly from the first, ie, the high thermal conductance of the heat pipe can make possible the physical separation of the heat source and the heat consumer (heat sink). Heat pipes >100 m in length have been constmcted and shown to behave predictably (3). Separation of source and sink is especially important in those appHcations in which chemical incompatibilities exist. For example, it may be necessary to inject heat into a reaction vessel. The lowest cost source of heat may be combustion of hydrocarbon fuels. However, contact with an open flame or with the combustion products might jeopardize the desired reaction process. In such a case it might be feasible to carry heat from the flame through the wall of the reaction vessel by use of a heat pipe. 

The greater portion of PVC is installed in the mechanically fastened roofing system a lesser portion is installed in fully adhered appHcations. Although PVC was once heavily used in ballasted roofing systems, there are only a small number installed in the 1990s. Fleece-back membrane is popular in the PVC constmction for both fully adhered appHcations as well as in appHcations where a separator sheet is needed. PVCs ate resistant to vafious weather conditions, bactefial growth, and industfial chemicals. These membranes ate chemically incompatible with bituminous materials. PVCs ate offered in a variety of colors. The physical characteristics of a PVC membrane have been described (15). 

PVC should not be melt-mixed with acetal polymers. These polymers are chemically incompatible mixing could cause rapid decomposition and gas evolution. 

Chemical incompatibility charts can help in organizing available data on the incompatibilities existing between expected mixtures. Frurip (Frurip et ah, 1997) gives one procedure for developing a chemical compatibility chart while describing some of the tools available. CCPS G-13 also provides a table of known incompatibility hazards. 

R.P. Pohanish and S.A. Greene, Rapid Guide to Chemical Incompatibilities, J. Wiley Sons, New York, 1997. ISBN 0471288020. 

If there is a chemical incompatibility between the liquid and an o-ring rubber compound, or if heat is generated from too much spring tension, this will be evident within a few hours or days. Galvanic corrosion or inadequate spring tension w ill reveal itself in a few weeks. 

Chemical incompatibility can manifest itself in many ways however, discussions will be limited to those combinations resulting in fires, explosions, extreme heat, evolution of gas (both toxic and nontoxic), and polymerization. 

Dyes from textile manufacturing that produce steam discoloration and may also present some chemical incompatibility (with amine treatments for example)... 

Industrial process contamination results in Cross-contamination Malodors and discoloration Sticky films and varnishes Stable foams Chemical incompatability Impingement corrosion Fluctuating pH/acid corrosion... 

When it is mixed with potassium nitrite in the melted state (440°C), ammonium nitrate detonates. The presence of rust decreases the temperature of the explosion to 80-120°C. This behaviour is linked to the chemical incompatibility of the nitrite ion and ammonium ion. 

Issues relating to chemical incompatibility and instability may be less significant for solid dosage forms compared with liquid and semi-solid preparations. 

This section focuses on environmental conditions that may result in physical or chemical incompatibilities between wastes and reservoirs. Determining the potential for incompatibility is a part of the geochemical fate assessment that must be undertaken for any injection project because of possible... 

Pohanis, Richard P, and Stanley A. Greene. Wiley Guide to Chemical Incompatibilities. 2nd ed. New York John Wiley Sons, 2003. 

A detailed strategy for the approach to safety testing is provided in Chapter 2 (Figures 2.3, 2.4, and 2.5) and in Chapter 3 (Figure 3.4). These schemes are directed to the investigation of thermal instabilities, chemical incompatibilities, including acid, water, and oxygen incompatibility, and other factors important to potential unstable behavior. 

Safety aspects are considered in two phases (Fig. 11). In the rule based synthesis some safety related rules are applied in process concept selections. These include rules such as separate corrosive or hazardous components first or avoid using chemically incompatible substances in the same process. ... 

Chemical Incompatibility Hazards While N2 and C02 may act as inerts with respect to many combustion reactions, they are far from being chemically inert. Only the noble gases (eg., Ar and He) can, for practical purposes, be regarded as true inerts. Frank (Frank, Inerting for Explosion Prevention, Proceedings of the 38th Annual Loss Prevention Symposium, AIChE, 2004) lists a number of incompatibilities for N2, C02, and CO (which can be present in gas streams from combustion-based inert gas generators). Notable incompatibilities for N2 are lithium metal and titanium metal (which is reported to burn in N2). C02 is incompatible with many metals (eg., aluminum and the alkali metals), bases, and amines, and it forms carbonic acid in water,... 

The first four questions address substances that are reactive with air, water, or ordinary combustibles—materials that are almost certain to be in close proximity to the reactive substances. The next question addresses self-reactive materials. This is followed by a final question combined with a series of steps for addressing chemical incompatibility. 

MSDSs generally contain the most apparent chemical reactivity hazards. However, they cannot be relied upon to give complete information, particularly with regard to chemical incompatibilities and chemical reactivity at actual process conditions. 

The accurate assessment of binary chemical compatibility is an important part of the safe handling, transport and processing of industrial chemicals. The most common and convenient way to represent binary chemical incompatibility is by a simple two-dimensional chart or matrix. Binary compatibility charts are an extremely useful teaching tool for new and even veteran employees. 

Several types of hazardous chemical reactivity, with 36 percent attributed to chemical incompatibility, 35 percent to runaway... 

Chemical incompatibility between two or more substances-These hazards occur when a chemical is suddenly mixed or comes into contact with another chemical, resulting in a violent reaction. 

Among governmental regulations, voluntary guidelines, or trade association codes of practice, there is no standard approach to classifying hazardous chemical reactivity. A variety of methods are used to address self-reactivity (e.g., decomposition reactions and some polymerization reactions) and chemical incompatibility. 

Responses to the CSB industry survey50 indicate that most companies consult a variety of information sources as a first step in compiling data on reactive hazards. However, respondents prefer literature sources and expert opinion over computerized tools such as CHETAH, The Chemical Reactivity Worksheet, or Bretherick s Database of Reactive Chemical Hazards. Such programs can be used to predict the thermal stability of compounds, reaction mixtures, or potential chemical incompatibilities. In some cases, they provide an efficient means of identifying reactive hazards without having to conduct chemical testing. Survey responses showed that five of nine companies consider computer-based tools not valuable. Only two of the surveyed companies use The Chemical Reactivity Worksheet.51... 

Approximately 36 percent of incidents in the CSB data are related to chemical incompatibility. CCPS provides information on managing chemical incompatibility hazards in guidelines for chemical reactivity. It emphasizes the need to systematically examine possible chemical incompatibilities and describes the use of interaction matrices (CCPS, 1995a, p. 7 1995b, p. 108).52>,53 This guidance applies to chemical manufacturers as well as to other industries. 

Seven of nine respondents use chemical interaction matrices to identify potential chemical incompatibilities. Most use a binary matrix (i.e., the mixing of only two chemical components at a time). Respondents indicated that literature or expert opinion are important sources of data for the matrix. 

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