How Hot Did It Get

How Hot Did It Get?

www.warrenforensics.com

Presented by

Jeffery H. Warren, Ph.D., P.E., CSP, C.F.E.I.S. Dyer Harris, Ph.D., P.E., C.F.E.I

Clemson, SC Fire: 11/11/1998Startup: 2/18/97


Typical Installation


2 by 6 studs

Cement Board

Stainless Steel Sheet

2 by 6 or 2 by 12 Blocking

Mounting Bracket Detail


Clemson, SC


Mounting Bracket

Clemson, SC- Back of Cheesemelter


Extensive Heat Damage

Clemson, SC


Fire Origin

Blocking Remains

Durock

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Trussville, AL Inspection 3/10/99


Niceville, Florida Inspection 3/26/1999Startup Date: 9/30/97


Heat Damage

Tullahoma, Tennessee


The Warren Group Laboratory





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Maximum Temperature Distributions in Wall at Point A

Inside of

Cheese

Melter

Back of

Cheese

Melter

Bolt Head

Location

Betw een

Stainless

Steel &

Duroc

Front of 2 x

12 Wood

Blocking

Back of 2 x

12 Wood

Blocking

Interior

Surface of

Back Wall

Panel

Location in Wall

Tem

pera

ture

F

Test 1: Cheese Melter

Test 2: Cheese Melter & Steak Grill

Test 3: Cheese Melter & Fryer w ith Water

Test 4: Cheese Melter & Fryer w ith Grease


Insert Figure 1, Appendix 9 W8168


Sebring, FL


Report 60093


Left Mounting Bracket

Right Mounting Bracket

Gas Control Valve Knob

Fire Triangle

Ignition

SourceFuel

Oxygen


Prolonged, especially cyclic, exposure to heat decomposes wood.

Temperatures do not have to be high to cause charring.

Carbonaceous material self-heats from C + O2 CO2

Key: Can the heat be removed (conducted out) faster than it

is generated? If not, ignition and fire can result


An estimate is given by Fourier’s equation, a century old.

Note the factors involved: T, x, q, material α, and time

(leave the solution details to us)


A Modine Heater enclosed

and jammed into a closet

–Hot exhaust

flue pipe




Fire place insert test, full scale with exemplar

Allegations Made

• Regulator defectively manufactured

• Leaks existed before the fire

• Lever arm was not inserted in diaphragm plate


Testing Regulator

• ½ inch NPT

• ANSI Z21.18 gas appliance regulator

• ANSI Z21.80 line regulator

• Rated for 250,000 BTUH of natural gas


Testing Apparatus: Oven

• Convection oven with capacity to 600°F


Results: Housing Integrity

• Some leakage when exposed to temperatures at or above 500°F

• Housing did not leak below 500°F

• Onset of leakage correlates well with first stage degradation of NBR diaphragm

• Amount of leakage not always greater when exposed to higher temperature


Conclusions:

• Regulator operated at temperatures well above manufacturer’s stated limit

• Post fire examination and testing of regulators can be used to determine fire exposure and explain post fire damage



–Who has the first question?

How Hot Did It Get

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