Professional Qualifications for Fire Investigation · A witness who is qualified as an expert by knowledge, skill, experience, training, or ... 1.3.7* The fire investigator shall

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Professional Qualifications for Fire Investigation

IAAI ITC Orlando, FL

April 26, 2016

John J. Lentini, IAAI-CFI Diplomate, American Board of Criminalistics

How to Survive the

Cross- Examination

from Hell

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FRE Rule 702 A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

FRE Rule 702 (a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied the principles and methods to the facts of the case.

FRE Rule 702 A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

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Who is qualified?

And what standard says so?

NFPA 1033 is a Standard

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NFPA 1033 is a Standard It applies to everyone who

investigates fires

Even if it is not adopted into law in your jurisdiction, it is

still an industry standard.

A lawyer who knows NFPA 1033 can use it to get you excluded as unqualified.

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1.3.7* The fire investigator shall remain current with investigation methodology, fire protection technology, and code requirements by attending workshops and seminars and/ or through professional publications and journals.

V. I will regard it my duty to know my work thoroughly. It is my further duty to avail myself of every opportunity to learn more about my profession.

1.3.8* The investigator shall have and maintain at a minimum an up-to-date basic knowledge of the following topics beyond the high school level:

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(1) Fire science (2) Fire chemistry (3) Thermodynamics (4) Thermometry (5) Fire dynamics (6) Explosion dynamics (7) Computer fire modeling

(8) Fire investigation (9) Fire analysis (10) Fire investigation methodology (11) Fire investigation technology (12) Hazardous materials (13) Failure analysis and analytical tools

Added in 2014…

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(14) Fire protection systems (15) Electricity and electrical systems (16) Evidence collection and documentation

The data are available at CFI Trainer

The data are available at in NFPA 921

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Q.  Are you familiar with NFPA 1033? Q. Do you agree that NFPA 1033 applies to

you? Q. Do you meet the requirements of NFPA

1033? Q. Do you agree that NFPA 1033 requires

you to have knowledge of certain subjects beyond the high school level?

Q. So if I ask you about a subject at the high school level, would you agree that you should be able to answer it?

Q.  Define thermodynamics A. Thermodymamics is the study of energy conversion between heat and mechanical work, and subsequently the macroscopic variables such as temperature, volume and pressure.

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Actual transcript from a 30-year CFI Q. What courses have you taken that would qualify you as post-secondary education in thermodynamics? A. I don't know. Q. Do you know what the definition of "thermodynamics" is? A. No. Q. Do you know what the relationship between temperature, volume, and pressure is? A. No.

Actual transcript from another 30 year CFI

Q. What are the basic units of energy? A.· I'm -- I'm not going to say right now.· Don't know right now. Q.· Okay.· What's the difference between energy and power? A.· We went over all this here this last year. I'm -- I don't know.· I'm not going to – Q.· What are the basic units of power? A.· I'm not sure.

2. The Chemistry and Physics of

Combustion

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Fire and Energy

NFPA 1033, 2009 edition 1.3.8* The investigator shall have and maintain at a minimum an up-to-date basic knowledge of the following topics beyond the high school level at a post-secondary education level: (1) Fire science (2) Fire chemistry (3) Thermodynamics (4) Thermometry

Two kinds of chemical processes

exist:

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Endothermic processes absorb

energy

Depressurizing a pressure can, e.g., a propane cylinder

A chemical cold pack consisting of ammonium nitrate and water

Melting of ice

Vaporization of water

Pyrolysis

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Exothermic reactions release

energy

Corrosion of metals Setting of concrete Most Polymerization Reactions Fire

Reaction rates increase as temperature

increases

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Rule of thumb:

Rate doubles with each increase of

10 ºC

The energy released by an exothermic reaction can

increase the reaction rate, resulting in the release of

even more energy.

This can result in “thermal runaway.”

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Fire is an exothermic chemical reaction that gives off energy in the form of heat and light.

Understanding fire requires a basic

understanding of energy.

Energy and Temperature • When matter absorbs energy, its

temperature increases.

•  Increased temperature is manifested by an increase in molecular motion or molecular vibration.

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Energy and Temperature •  The typical speed of an O2

molecule at room temperature is ~480 m/s, or 1080 mph.

• Molecular speed is proportional to the square root of the absolute temperature.

Temperature is the measureable effect of the absorption of energy by matter.

Energy

The ability to do work Or

The ability to heat something up

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Energy is a property of matter that is manifest as an ability to perform work, either by moving an object against a force or by transferring heat.

Heat • Because it could flow,

Lavoisier thought it was a substance called Caloric

• Rumford and Joule proved it was energy

Unit of work equals the unit of force multiplied by the unit of distance.

In the metric system, the unit of force is the newton. A newton is that force required to accelerate a

mass of one kilogram to an acceleration of one meter per

second2. (f=ma)

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In the English system, the unit of force is the pound. A foot-pound is that force required to

accelerate a mass of one pound vertically against the force of gravity (9.8 m/sec2)


The basic unit of energy is the

newton-meter, also known as a joule (J)


Energy can also be expressed as

calories or Btus or kWh.

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1 calorie~4.2 J 1 Btu~1054 J 1Btu~252 c

1kWh=3.6 MJ


1 foot= 0.305 meters 1 pound = 0.454 kg

1 m/sec2 X 9.8=9.8 m/sec2

So 1 foot-pound = 1.356 Joules

http://joshmadison.com/software/ convert-for-windows/

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Joules are small

The amount of hydrocarbon or wood fuel that requires only one gram (~700 cc) of

oxygen, releases 13.1 kJ

How does moving a weight over a distance help us understand

heat transfer? Rumford found that we can

equate moving a fixed weight over a fixed distance with

raising a fixed body of water by a fixed number of degrees.

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One calorie is the amount of heat required to raise the

temperature a one gram of water by one degree Celsius.

Actually from 14.5 ºC to 15.5 ºC.

One British Thermal Unit is the amount of heat required to raise the temperature a one pound of water by one degree Fahrenheit.

Actually from 63 ºF to 64 ºF.

The quantity of water is greater (454 g) The temperature increase is less (.555 ºC)

1 Btu = 454 X .555= 252 Calories

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Work = Heat But it takes exactly the same amount of work to lift a 100 pound weight ten feet in one second or in one hour. (1000 foot pounds).

Work = Heat But it takes exactly the same amount of heat to raise the temperature of one pound of water by 10 degrees in one second or in one hour. 10 Btu

(assuming perfect insulation)

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Work = Heat

Time is of the essence!

To describe a heat source, we need to be able to describe the amount of energy it

gives off per unit time.

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Energy per unit time is

POWER

Power is a property of a process such as fire that describes the amount of energy that is emitted, transferred, or received per unit time. Power is measured in joules per second (J/s) or watts (W).

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Units of Power

1 Joule/second = 1 Watt 1 Btu/second = 1054 Watts

1 Btu/hr = 0.293 Watts 1000 Btu/second = 1.054 MW

Gas Burners

12,000 Btu/h stovetop = 3,500 W = 3.5 kW 40,000 Btu/h water heater = 11.72 kW 125,000 Btu/h furnace = 36.6 kW

Gas Burners

Consider the energy released if the 12,000 Btu/h stovetop burner loses

its pilot, but finds an ignition source an hour later, and burns in 1 sec

12,000 Btu/s = 1,260 kW

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Heat Release Rate The MOST important attribute of a fire is its heat release rate

(HRR). Knowing the HRR allows us to predict how a fire

will behave, and relate it to our everyday experience.

Heat Release Rate per Unit Area

If we spread the 36 kW from our gas furnace over the

entire house, we can keep it nice and toasty on a cold

winter day.


But if we concentrate it all in an area 3’ by 3’, or 1m by 1m, then

we have a concentration of 36 kW/m2

Enough to raise some serious hell.

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The concentration of heat in a given area is known as heat FLUX.

Don’t be this guy Q . What's radiant heat flux? A. The -- I know what radiant heat is. I don't know the specific definition of radiant heat flex. THE REPORTER: Flux or flex? MR. SKLAR: Flux, F-L-U-X. THE WITNESS: Flux, okay.

Heat flux is

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Typical Radiant Heat Fluxes Approximate Radiant Heat Flux (kW/m2) Comment or Observed Effect 1.4 Thermal radiation from the sun. Sunburn in < 30 min 2.5 Common exposure while firefighting. 4.5 Human skin blisters in 30 sec, with 2nd degree burn 6.4 Human skin blisters in 18 sec, with 2nd degree burn 10.4 Human skin has pain in 3 sec, blisters in 9 sec 12.5 Wood volatiles ignite with extended exposure and piloted

ignition

Typical Radiant Heat Fluxes Approximate Radiant Heat Flux (kW/m2) Comment or Observed Effect 16 Human skin experiences pain in 3 sec, blisters in 5 sec with

2nd degree burn injury 20 Heat flux on residential floor at the onset of flashover 29 Wood ignites spontaneously after prolonged exposure 52 Fiberboard ignites spontaneously after 5 sec 80 Heat flux for test of turnout gear 170 Maximum measured heat flux in a post-flashover

compartment

Heat of Combustion

Each substance has its own heat of combustion. This property is reported as energy per unit mass.

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Heat of Combustion

kJ/kg or calories/gram or Btu/lb or, for gases, kJ/m3 or Btu/ft3

Mass Loss Rate

At a given point of time in a given fire, each fuel has its own mass loss rate, measured in mass per unit time, or g/sec.

Heat Release Rate

Equals the heat of combustion times the mass loss rate.

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Heat Release Rate

Because the mass loss rate changes over time, so does the heat release rate.

Heat Release Rate

What causes the mass loss rate to increase?

Heat Release Rate

What causes the mass loss rate to decrease?

(More on this in Chapter 3)

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Heat Release Rate


kJ/kg X kg/sec

Heat Release Rate


kJ/kg X kg/sec = kJ/sec = ??

Total Energy Impact

Equals the radiant heat flux times the number of seconds of exposure.

kW/m2 X sec = kJ/sec/m2 X sec =

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Total Energy Impact


kW/m2 X sec = kJ/sec /m2X sec =

Total Energy Impact


kW/m2 X sec = kJ/sec /m2X sec = kJ/m2

Total Energy Impact


kW/m2 X sec = kJ/sec /m2X sec = kJ/m2 (energy per unit area)

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Total Energy Impact Determines the degree of damage. Determines the size and shape of a fire pattern. Along with material properties.

HRR 12 seconds post flashover

150 kW/m2

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Total Energy Impact in 2 minutes


150kW/m2 X 120 sec = 18 MJ/m2 (18,000 kJ/m2)

Energy Concepts Review

1. Energy 2. Power 3. Heat Flux 4. Total Energy Impact

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If you cannot define and explain these concepts,

then you are not a qualified fire investigator per NFPA 1033.

Don’t be this guy! Q. What are the basic units of power called? A. AC and DC. Q. I'm sorry? A. AC and DC. Q. Have you ever heard of a watt? A. Yes, sir.

Don’t be this guy! Q. Do you know what a watt is? A. No, sir. Q. Okay. How is the size of a fire measured? A. I'm unsure at this time. Q. Okay. What is radiant heat flux? A. I'm unsure at this time.

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Or this guy! Q. What are the basic units of energy? A. Endothermic and exothermic.

1.Energy

Energy is the ability to do work. (Move an object against a force, or heat something up-moving objects at the molecular level)

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1.Energy Energy is a property of matter that is manifest as an ability to perform work, either by moving an object against a force or by transferring heat.

1.Energy

Energy is measured in joules, or calories or Btus or kWh.

2. Power

Power is energy per unit time.

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2. Power

Power is energy per unit time. How fast, or at what rate is the energy released?

2. Power

Power is a property of a process such as fire that describes the amount of energy that is emitted, transferred, or received per unit time. Power is measured in joules per second (J/s) or watts (W).

2. Power

Power is measured in watts, or kilowatts or megawatts, or Btu/hr.

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2. Power

Power is measured in watts, or kilowatts or megawatts.

1 watt = 1 joule/second

2. Power

Energy release rate = Heat release rate. ERR or HRR is measured in kW or MW.

3. Radiant Heat Flux

Radiant heat flux is the amount of power per unit area.

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Radiant heat flux is measured in kW/m2, or W/cm2. (There are 10,000 cm2 in 1

m2.)


The sun bathes the earth in a radiant heat flux of ~1kW/m2

or 0.1 w/cm2.


At the onset of flashover in a typical residential fire, the radiant heat flux on the floor is about 20 kW/m2, or 2 W/cm2.

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4. Total Energy Impact

Total energy impact is the heat flux (intensity) multiplied by the time of exposure (duration).

4. Total Energy Impact

Total energy impact is measured in energy per unit area, or kJ/m2.

Basic Chemistry

States of Matter

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+~10%

X~100-1500

States of matter 18 ml of water makes 22,400 ml of vapor (1244) 82 ml of propane makes 22,400 ml of vapor (272) Water is an exception to the solid èliquid rule.

The Behavior of Gases •  A gas is a substance that is in the gas

phase at standard temperature and pressure.

•  A vapor is the gas phase of a substance that is liquid at standard temperature and pressure.

•  Gases and vapors have no shape or size of their own and can expand without limit.

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The Behavior of Gases

Gases may be elemental or

molecular.

Elemental Gases

Except for the inert gases (aka rare gases aka noble gases), elemental gases are diatomic.

Monatomic Elemental Gases

• Helium (He) • Neon (Ne) • Argon (Ar) • Krypton (Kr) • Xenon (Xe) • Radon (Ra)

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Diatomic Elemental Gases

• Hydrogen (H2) • Nitrogen (N2) • Oxygen (O2)* • Fluorine (F2) • Chlorine (Cl2)

Molecular Gases •  Carbon monoxide (CO) •  Carbon dioxide (CO2) •  Formaldehyde (CH2O) •  Methane (CH4) •  Propane (C3H8) •  Butane (C4H10) •  Acetylene (C2H2) •  Ammonia (NH4)

The Behavior of Gases • Gases expand and contract with

changes in temperature and pressure.

• Gases will be uniformly distributed throughout the internal volume of any container.

• Gases follow the ideal gas law. (to a good first approximation.)

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The Behavior of Gases

PV = nRT Where P is pressure

V is volume R is the universal gas constant

(8.314472 J/mol K) T is Temperature in K

n is the number of molecules

The Behavior of Gases Reducing the size of a closed

container by half causes the pressure to double.

Example:

The Behavior of Gases Doubling the number of molecules

of gas, by adding more, and allowing the container to expand doubles the volume.

Example:

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The Behavior of Gases Doubling the number of molecules

of gas, by adding more, and holding the volume constant doubles the pressure.

Example:

The Behavior of Gases Raising the temperature from 298K

to 596K doubles the volume if the container is allowed to expand, or doubles the pressure if the volume is held constant.

Example:

Temperature Scales

K = Kelvins 298K = 25 °C = 77 °F

596K = 323 °C = 613 °F

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Temperature Scales

Kelvin is an absolute temperature scale, based on absolute zero, the temperature at which all molecular motion stops.

596 K is twice as hot as 298 K. 323 °C is twice as hot as 25 °C

Temperature Scales

Kelvin is an absolute temperature scale, based on absolute zero, the temperature at which all molecular motion stops.

596 K is twice as hot as 298 K. 613 °F is twice as hot as 77 °F

Temperature Scales Celsius is a relative temperature scale,

based on the behavior of water. Water freezes at 0 °C and boils at 100 °C.

(100 degree difference) 200 °C is NOT twice as hot as 100 °C

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Temperature Scales 200 °C is NOT twice as hot as 100 °C

200 °C = 473.15 K 100 °C = 373.15 K

473.15 ÷ 373.15 = 1.268

200 °C is about 27% hotter than 100 °C

Temperature Scales Fahrenheit is a relative temperature

scale, based on the behavior of water. Water freezes at 32 °F and boils at 212 °F.

(180 degree difference)

Temperature Scales To convert from °C to °F, multiply

by 9/5) and add 32. 180/100 = 9/5

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Temperature Scales

To convert from °F to °C, first subtract 32, then multiply by 5/9.

100/180 = 5/9

Combustion of Gases

Hydrogen is the simplest

2H2 + O2 è 2H2O

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Combustion of Gases

Methane is the simplest organic (carbon based) fuel gas

CH4 + 2O2 è CO2 + 2H2O

Combustion

Generally: The complete combustion of a

hydrocarbon fuel yields carbon dioxide + water

CO2 + H2O

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Balancing Chemical Equations

It’s easy! All you do is make sure there are the same number of each kind of atom on each side of the arrow.

#CxHy + #O2 è #CO2 + #H2O


Start by counting carbons. Methane has one carbon CH4 + O2 è CO2 + #H2O


Next count hydrogens. Methane has 4 hydrogens…. CH4 + O2 è CO2 + #H2O

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Next count hydrogens. Methane has 4 hydrogens but water

only has 2. CH4 + O2 è CO2 + #H2O


Next count hydrogens. Methane has 4 hydrogens but water

only has 2. So double the water. CH4 + O2 è CO2 + 2H2O


Next count oxygens. CH4 + O2 è CO2 + 2H2O

2 on the left, 4 on the right

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Next count oxygens. CH4 + O2 è CO2 + 2H2O

2 on the left, 4 on the right

CH4 + 2O2 è CO2 + 2H2O

Combustion of Gases

Propane is another common fuel gas


Propane C3H8

C3H8 + O2 è CO2 + H2O 3 carbons 1 carbon 8 hydrogens 2 hydrogens 2 oxygens 3 oxygens

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Propane C3H8

C3H8 + O2 è 3CO2 + H2O

3 carbons 3 carbons 8 hydrogens 2 hydrogens 2 oxygens 7 oxygens


Propane C3H8

C3H8 + O2 è 3CO2 + H2O



Propane C3H8

C3H8 + O2 è 3CO2 +4H2O


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Propane C3H8

C3H8 + 5O2 è 3CO2 +4H2O


Combustion of Gases

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Combustion of Gases

Reducing the oxygen available

CH4 + 1.5O2 è CO + 2H2O

2CH4 + 3O2 è 2CO + 4H2O

Don’t be this guy! Q. What was your theory as to the cause of this fire? A. The cause of the fire was initiated from a propane weed burner and direct contact with the building construction of the floor. Q. Do you know how many BTUs are present in a typical cubic foot of propane? A. Not at this time.

Don’t be this guy! Q. Do you know what the chemical formula for propane is? A. I'm unsure at this time. Q. Can you write down the chemical equation that describes the burning of propane in air? A. I'm unsure.

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Don’t be this guy! Q. Do you know what the chemical formula for propane is? A. I'm unsure at this time. Q. Can you write down the chemical equation that describes the burning of propane in air? A. I'm unsure.

Combustion of Gases

C3H8 + 5O2 è 3CO2 + 4H2O One volume of propane needs 5

volumes of oxygen CH4 + 2O2 è CO2 + 2H2O

One volume of methane needs only 2 volumes of oxygen

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Combustion of Gases

Equal volumes of gas contain equal numbers of molecules

Avogadro’s Law

Combustion of Gases

One volume of propane needs 5 volumes of oxygen. Air is ~20% oxygen, so one volume of propane needs 25 volumes of air. One volume of methane needs 10 volumes of air.

Don’t be this guy! (who claims an Associates Degree in Fire Science)

Q . What's the concentration of oxygen in air? MR. DUNLAP: Objection. A. What's the concentration of it? BY MR. SKLAR: Q. Yeah. A. Like the air we breathe? 92 percent. I don't know if that's right or not but it's in that area. (not on this planet!)

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Or this guy! (A P.E.! working on a carbon monoxide poisoning case)

Q. How much -- what percentage of air is oxygen generally speaking? A. Best I remember around 89 percent -- oh, that's nitrogen, probably 10, 11 percent. I don't remember exactly.

Combustion of Gases

Burning one cubic foot of propane in 25 cubic feet of air releases 2,500 Btu.

2.6 MJ Burning one cubic foot of methane in 10 cubic feet of air releases 1,000 Btu.

1.055 MJ

Density of Gases

Density is mass per unit volume, as in grams per cubic meter. Air has a density of 1.297 kg/m3

(1.296 oz/ft3)

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Specific Gravity of Gases

Specific gravity of a gas is the ratio of the mass of the gas, compared to the mass of the same volume of air.


A mole of gas weighs as much as its molecular weight.

A mole of any gas has a volume of 22.4 liters.


Because equal volumes of gas contain equal numbers of molecules, if we know the molecular weight of a gas, we can calculate its specific gravity.

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What is the molecular weight of air? What is air?


What is the molecular weight of air? The atomic weight of oxygen is 16 grams per mole. The molecular weight of oxygen (O2) is 32 g/mol The atomic weight of nitrogen is 14 g/mol The molecular weight of nitrogen (N2) is 28 g/mol Air is 78% N2, 20.95% O2, 0.93% Ar, 0.04% CO2

*

* And rising


What is the molecular weight of air? Let’s just say 80% N2 and 20% O2

[80 (28) + 20 (32)] ÷ 100 = 29 (2240)+(640)=2880

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The specific gravity of ANY gas is its molecular weight divided by 29.


Hydrogen (H2) MW = 2

Specific gravity = 2/29 = 0.07


Helium (He) AW = 4


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Methane (CH4) MW = 16



Propane (C3H8) MW = 44



Carbon dioxide (CO2) MW = 44


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Specific Gravity of Vapors

Water (H2O) MW = 18



Toluene (C7H8) MW = 92



The vapors of all flammable liquids are heavier than air.

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There exist only 8 gases that are lighter than air

The 8 gases lighter than air are:

Hydrogen Acetylene Helium Ammonia Methane Illuminating Gas Carbon monoxide Ethylene

Stoichiometry and Flammable Limits

Stoichiometry deals with relative proportions of substances.

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Every chemical reaction has characteristic proportions


For a gas or vapor burning in air, a stoichiometric mixture exists when there is exactly enough air to completely burn all of the fuel.


A flammable gas mixture is one through which flames can propagate.

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If there is insufficient fuel, the mixture is too lean.

If there is insufficient air, the mixture is too rich.

The Chemistry and Physics of Combustion 37

2.6 The Behavior of Liquids

Any liquid, ignitable or not, when placed into a closed container, will begin to vaporize.If the temperature is held constant, the liquid will eventually appear to stop vaporizing.Appearances can be deceiving. The liquid continues to vaporize; but when the liquid andthe vapor above it are in a state known as equilibrium, the rate of vaporization equals therate of condensation. Relative humidity is a term applied to water in air. At any giventemperature, the concentration of water vapor above a still pool in a closed containerreaches a constant, and the air is said to be saturated. Such air has a relative humidity of100%. The percent of water in the air versus the amount of water that the air couldpotentially hold if it were saturated is called the relative humidity.

For the vapors of liquids other than water, the amount of liquid in the vapor phasecan be described as its concentration (% by volume in air) but the amount of vapor isusually determined by measuring its pressure. The concentration of a vapor above itscorresponding liquid is referred to as the vapor pressure, or partial pressure.

Vapor pressure is generally expressed in millimeters of mercury (mmHg). This measure-ment describes the height of a column of mercury in an evacuated tube — a barometer —that can be supported by the surrounding pressure. The air around us exerts a pressure ofapproximately 760 mmHg, or about 30 inches of mercury. This is the combined pressure

Figure 2.6 Schematic representation of the concept of flammable limits (also known asexplosive limits).

2082_C002.fm Page 37 Saturday, August 20, 2005 10:24 PM


The stoichiometric mixture is always in the flammable range.

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One volume of methane requires 10 volumes of air to burn (9%). Its flammable range is 5 to 15%.


One volume of propane requires 25 volumes of air to burn (3.8%). Its flammable range is 2.2 to 9.5%.

The Behavior of Liquids

All liquids vaporize. In order to burn, an ignitable liquid must be in the vapor state.

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Vapor Pressure

Vapor pressure is the concentration of the liquid molecules in the air above a pool of liquid, expressed in millimeters of mercury (mmHg).

Vapor Pressure

1 atmosphere is 760 mmHg. (29.92 inches) 1% by volume in air is 7.6 mmHg

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Flash Point

The temperature at which the concentration of vapors above a still pool of liquid is equal to the lower limit of flammability.

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Raoult’s Law

The vapor pressure of a compound above a mixture of liquids equals the vapor pressure of the pure compound times the fraction of the compound in the liquid

Raoult’s law in action


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Density of Liquids

As with gases, density is mass per unit volume, as in grams per cubic centimeter, or pounds per gallon.

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Specific Gravity of Liquids

Gases compare with air. Liquids compare with water. Because the density of water is 1 gram per cc, specific gravity and density mean about the same thing when applied to liquids and solids.


Because water is polar and hydrocarbons are non-polar, they do not mix with water. Almost all ignitable liquids are less dense than water, and their specific gravity is less than 1. They float.


Some polar liquids, such as light alcohols and acetone, mix with water.

Light alcohols and acetone seldom leave residue, and are seldom found in fire debris samples.

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The Behavior of Solids

Not just solidified liquids

The Behavior of Solids Metals

Refractories Polymers

Polymers

Natural Synthetic

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Natural Polymers

Silk Wool Wood

Wood

Cellulose Hemi cellulose

Lignin

Cellulose

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Synthetic Polymers Polyethylene

Polypropylene Polyvinyl chloride

Polystyrene Polyurethane

Polyamide (Nylon) Polyester (Dacron)

Polymers

In order to burn, polymers undergo

pyrolysis.

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Pyrolysis

An irreversible decomposition caused by the breaking of chemical bonds due to the

application of heat

Pyrolysis

Pyrolysis is an endothermic reaction. It is not the same as

smoldering combustion, which is an exothermic reaction.

Solids Response to Heat

Melting Dehydration

Pyrolysis Charring

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Chemistry Concepts Review

1. Types of reactions 2. States of matter 3. Combustion equations

If you cannot define and explain these concepts,

then you are not a qualified fire investigator per NFPA 1033.

Don’t be this guy! Q. Do you know what the chemical symbol for hydrogen is? A. No, sir. Q. Do you know what the chemical formula for hydrogen gas is? A. No, sir. Q. Do you know what the chemical reaction for the combustion of hydrogen is? A. No, sir.

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Or this guy! Q. Do you agree that the combustion of hydrogen in the presence of air to form water is the simplest of all chemical combustion reactions? A. I don't know. Q. What is the chemical symbol for hydrogen? A. I don't know.

The Judge said, “I’m sorry. If you don’t know H2O, you will not be rendering opinion testimony in my courtroom.” -Hon. J. Michael Ryan DC Court, October 27, 2010

Review Which of the following reactions are exothermic? The melting of ice The boiling of water Setting of concrete Combustion of methane

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Review Which of the following reactions are exothermic? The melting of ice The boiling of water Setting of concrete Combustion of methane

Review How many volumes of air are required to burn one volume of natural gas (methane)?

Review

What is the energy content of a cubic foot of propane?

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Review

In the metric system, what is the basic unit for measuring energy ?

Review

Which ignitable liquids have vapors lighter than air?

Review

In the metric system, what is the basic unit for measuring power ?

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Professional Qualifications for Fire Investigation · A witness who is qualified as an expert by knowledge, skill, experience, training, or ... 1.3.7* The fire investigator shall