Chemical Reactivity Analysis in
the PEAC-WMD application
This month we?ll visit the Chemical Reactivity
Analysis feature and how it is implemented in the PEAC-WMD v5 application.
To give the reader a little background, we have the
opportunity to visit with a number of fire service and HAZMAT responders as we attend
workshops and conferences around the country. One of the questions that came
out from those encounters was ?can you tell me what happens if a certain chemical
comes in contact with another chemical?? Obviously this is a problem that arises
for many folks dealing with chemical spills and as a corollary to Murphy Law would
predict, ?if an ugly accident is going to happen, why not involve more than one chemical??
Some chemicals are pretty nasty all by themselves
and others aren?t that bad and we just need to be sure we mitigate the spill and prevent
them escaping to the environment. But then we have these situations where more
than one chemical is involved and the combination of two or more chemicals can lead
to problems beyond what any one of the single chemicals would have presented.
The EPA and NOAA have developed a methodology that
has attacked this problem and it provides a reasonable answer to the question of how
do the chemicals react and what can be expected. The application or tool is
referred to as the Chemical Reactivity Worksheet (http://www.epa.gov/OEM/cameo/react.htm)
and can be downloaded for free from the web site.
The EPA/NOAA application is based on initial work
that the California Department of Health Services undertook
a number of years ago to develop the original data and approach to assessing the reactivity
of chemicals. The EPA/NOAA group (Office
of Response and Restoration, National Ocean Service, National Oceanic and Atmospheric
Administration) headed by Dr. James Farr, have added additional information, refined
the data, and approach, the results of which are now displayed in the PEAC‑WMD
The description of the methodology, its limitations
and precautions related to using this feature are adapted from the description provided
by EPA/NOAA on their CAMEO web site and an earlier FEMA, DOT and EPA publication that
described the California Department of Health
The theory behind the Chemical
Reactivity Analysis is the fact that there
are literally tens of thousands of known chemicals used in daily commerce, and since
the consequences of only a small fraction of the possible combinations of these materials
have been reported in the general literature, none of these information sources can
claim (and none do) that combinations of unlisted materials will not produce a hazardous
reaction. Thus, although these information sources provide valuable guideposts
for evaluating potential chemical compatibility hazards, they are inherently limited
in scope, and cannot always be relied upon to provide the user with desired and/or
The initial project undertaken by Hatayama
et al. was to provide a user with a general indication of the typical effects
of mixing a material from one chemical family with a material from another family.
By focusing on the most common families of chemicals, i.e., materials with generally
similar molecular structure, and by studying the effects of combining the most reactive
chemicals in each family, the researchers were able to produce a relationship that
provides an excellent tool to screen lists of chemicals (as might be found at a facility
or in a transportation vehicle) for those which may pose an unusual and/or dangerous
threat when inadvertently combined (as might occur during some sort of process upset,
transportation accident, or mismanaged material transfer operation).
The PEAC-WMD Chemical
Reactivity Analysis feature will allow
the user to choose multiple (two or more) chemicals for analysis, but it will display
the potential reactions between only two chemicals at a time.
There is no ability to assess how a third or additional chemicals when mixed may effect
the reactions between the two chemicals being assessed.
Some chemicals, because of their molecular structure,
may fall into more than one chemical family. In these cases the Chemical
Reactivity Analysis will assess the potential reactions for each family against
the chemical family(ies) to which the other chemical belongs. We?ll show an
example in describing how the feature displays information.
The user should also understand that not all chemicals
in the PEAC-WMD database have been assigned a chemical family(ies). If the Chemical
Reactivity icon 
is not displayed on the screen when an entry in the List Box is highlighted,
then the material has not yet been assigned a family and cannot currently be added
to the Chemical Reactivity Analysis List.
The user should also understand that when two chemicals
are assessed, there is a potential for multiple results or products from the interaction,
meaning there may be more than one result or product. Likewise, there may be
no potential reactions predicted from the mixing of two chemicals. If that occurs,
the Chemical Reactivity Analysis will indicate no potential reactions are expected.
It is very important that users of
the Chemical Reactivity Analysis read and understand the following words of
caution before using this feature of the PEAC-WMD system. These words of caution
are adapted from the ?Handbook of Chemical Hazard Analysis Procedures? (referenced
above) that provided one of the first public implementations of the Hatayama,
et al. developed approach.
USE CAUTION WHEN USING THE CHEMICAL REACTIVITY
The Chemical Reactivity Analysis is intended
to provide an indication of some of the hazards that can be expected
upon mixing of chemical substances. Because of the differing activities of the
thousands of compounds that may be encountered, it is not possible to
make any analysis definitive and all-inclusive. It cannot be assumed that members
of chemical families not listed in the analysis will be compatible with each other
or with listed families. Although the analysis generally will indicated when
there is no hazardous incompatibility expected between the families being considered,
it cannot be guaranteed that this will always be the case. Detailed instructions
as to the hazards involved in handling and/or disposing of any given substance should
be obtained from the originator of the material or other expert source of information.
The potential reaction consequences predicted by
the analysis are based on pure chemical reactions only at ambient temperature and
pressure. Concentration, synergistic, and antagonistic effects have been assumed
not to influence the reactions. The reactions have not been validated on actual
materials containing individual chemicals.
To the above caution must be added the observation
that the analysis is solely applicable to the combination of two materials
from different families. The addition of one or more other materials to a mixture
may (or may not) produce substantially different hazards. The analysis should
not be used in any attempt to identify materials that may be self-reactive, i.e.,
capable of runaway exothermic polymerization, runaway exothermic decomposition, explosion,
or other hazardous activity upon simple heating or exposure to air.
How the Chemical Reactivity Analysis works
When the PEAC-WMD application is initially started,
the Chemical Reactivity Analysis List is empty by default. Once an entry
has been selected, either by clicking on the Chemical Reactivity icon 
or selecting Tools|Add to Reactivity List from the pull down menu (see Figure
1), a dynamic list is created within the PEAC-WMD application that contains the selected
The Chemical Reactivity Analysis List can
be viewed by clicking on the Lookup By pull-down list and selecting Reactivity
Chemicals from the list, see Figure 2.
Once the user has selected Reactivity Chemicals,
the List Box will display the names of those entries selected for the Chemical
Reactivity Analysis List, see Figure 2.
Figure 1 ? Adding to the Chemical Reactivity Analysis List
If the user elects to remove an entry from the Chemical
Reactivity Analysis List, highlighting the entry in the List Box can do
this and then clicking on the Remove Chemical Reactivity icon  at
the top left of the screen, or click on Tools|Remove from Reactivity List,
see Figure 2.
Figure 2 ? Displaying the Reactivity Chemical List and Removing Entries from the List
All the databases of information on each of the chemicals
is accessible from the screen as before, CPC, recommended respirators, synonyms and
ERG information, even accessing a PAD Calculator or accessing the Explosion
Calculator are available.
Before displaying and assessing the potential
reactions that may occur with another chemical, it
is important to review two pieces of information related to the individual
chemicals selected: (1) information specific to the hazardous material selected,
and (2) the general information related to the Chemical Family(ies) the hazardous
material fits into. Both of these pieces of information are located in the Reactivity
Information selection, which can be selected as shown
in Figure 3. The first portion of the Reactivity Information display
is shown in Figure 4, and relates to specific information on the selected hazardous
Figure 3 ? Selecting Reactivity Information
Figure 4 ? First portion of the Reactivity Information
is specific to the material
Since air and water are the two most common chemical
reactants that a material may come in contact with during an incident, it is important
to review what these reactions might be. The first information displayed is
the Special Hazards associated with this hazardous material. This information
is broken into three portions:
Special Hazards - which can be none or one or more
of the following seven different listings (Highly flammable, Explosive, Polymerizable,
Strong oxidizing agent, Strong reducing agent, Peroxidizable compound, or Radioactive
Either Water reactive or No rapid reaction
with water, and
Either Air reactive or No rapid reaction
This information provides the user some immediately
important information about the Chemical Family the selected hazardous material
Immediately after the Special Hazards are
displayed the Air and Water Reactions, which are specific for the hazardous
The next item to be reviewed is the possible reactions
for the material selected, which are listed under the Chemical Profile header.
These first three portions of the Reactivity Information database for the hazardous
material Chlorine are shown in Figure 4.
Remember ? a specific hazardous material may fall
into more than one Chemical Family or Reaction Group; therefore there
may be more than one set of generic information displays regarding the hazardous material
to review. To illustrate this fact, using our example of Chlorine as the hazardous
material, it falls into two Chemical Families or Reaction Groups: (1)
Inorganic Oxidizing Agents and (2) Strong Halogenating Agents. This is shown
in Figure 5, where the Reactivity Information database display has been scrolled
down below the Chemical Profile information for Chlorine to display information
for Inorganic Oxidizing Acids. Figure 6, provides an example of the Reactivity
Information database display for Strong Halogenating Agents which is below the
Inorganic Oxidizing Agents information for Chlorine.
Figure 5 ? Generic information for Inorganic Oxidizing
Figure 6 ? Generic information for Strong Halogenating
To demonstrate the feature of assessing chemical
reactivity the following materials are selected, Acetone and Bromine. These
are selected as shown earlier in Figure 1, by highlighting each material and clicking
on the Reactivity icon 
to add them to the Chemical Reactivity Analysis List. Before accessing
the reactivity information related to these two chemicals, the user should review
the Reactivity Information as described in Figure 3 and 4. To display
the potential reactions of Acetone and Bromine, the user should select Reactivity
Chemicals as shown in Figure 7. The dynamic Chemical
Reactivity Analysis List is displayed and the user can access the Reactions information
using the earlier described EPA/NOAA approach by clicking on the Database Selection
Field and selecting Reactions from the drop-down list as shown in Figure
Figure 7 ? Selecting the Chemical Reactivity Analysis
Figure 8 ? Accessing the Reactions information
The Reactions Summary display, as shown in
Figure 9 displays the following information:
list of what entries are being assessed (maximum of 5 entries are allowed).
summary of all potential reactions is provided. Depending on the number of materials
selected and the individual materials selected to be included in the Chemical Reactivity
Analysis there may be none or multiple potential reactions that can occur.
This summary provides a listing of all potential reactions between all the possible
combinations of materials that were selected for the Chemical Reactivity Analysis
Figure 9 ? Displaying the potential reactions that
To demonstrate an example where no predicted reactions
are expected, Figure 10 is the Reactions analysis screen for Acetone and Ethanol
Figure 10 ? Example of materials that are not
expected to have reactions
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