NIST GCR 15-917-36
 

Development of Standardized Cooking 

Fires for Evaluation of Prevention 

Technologies: Data Analysis 

Joshua B. Dinaburg 

Daniel T. Gottuk 

In collaboration with the Fire Protection Research Foundation 

This publication is available free of charge from: 

http://dx.doi.org/10.6028/NIST.GCR.15-917-36

and www.nfpa.org/foundation 
 

 

 

 

NIST GCR 15-917-36 

Development of Standardized Cooking 

Fires for Evaluation of Prevention 

Technologies: Data Analysis 

Prepared for 

U.S. Department of Commerce 

Engineering Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899-6880 

By 

Joshua B. Dinaburg 

Daniel T. Gottuk

In collaboration with the Fire Protection Research Foundation 

This publication is available free of charge from: 

http://dx.doi.org/10.6028/NIST.GCR.15-917-36

and www.nfpa.org/foundation 

July 2014 

U.S. Department of Commerce 

Penny Pritzker, Secretary 

National Institute of Standards and Technology 

Willie May, Under Secretary of Commerce for Standards and Technology and Director 
 

 

 

Development of Standardized
 

Cooking Fires for Evaluation of
 

Prevention Technologies: Data Analysis
 

Final Report 

Prepared by: 

Joshua B. Dinaburg and Dr. Daniel T. Gottuk 

Hughes Associates, Inc.
 

3610 Commerce Dr., Suite 817
 

Baltimore, MD 21227
 www.haifire,com 

© July 2014 Fire Protection Research Foundation 

THE FIRE PROTECTION RESEARCH FOUNDATION
 

ONE BATTERYMARCH PARK
 

QUINCY, MASSACHUSETTS, U.S.A. 02169-7471
 

E-MAIL: Foundation@NFPA.org
 

WEB: www.nfpa.org/Foundation
 
 

—— Page i ——
 

 

 

 

 

 

 

 

 

 

 

 

 

 

FOREWORD
 

Beginning in 2010, the Foundation began a program to review the potential effectiveness of 

various technologies potentially capable of preventing cooking range top fires. A workshop 

conducted as part of that project considered the emergence of commercial products on the market 

and identified the need to develop standardized tests and criteria to evaluate the performance and 

effectiveness of such devices. This report summarizes and analyzes the results of two live fire test 

series conducted to form the basis for such a test protocol. 

The Research Foundation expresses gratitude to the report author Joshua B. Dinaburg and Dr. 

Daniel T. Gottuk, who is with Hughes Associates, Inc. located in 3610 Commerce Dr., Suite 817, 

Balitmore, MD 21227 The Research Foundation appreciates the guidance provided by the Project 

Technical Panelists and all others that contributed to this research effort. In particular the 

Foundation thanks the National Institute of Standards and Technology for the award of funding 

for the project. 

The content, opinions and conclusions contained in this report are solely those of the authors. 

About the Fire Protection Research Foundation 

The Fire Protection Research Foundation plans, manages, and communicates research on a broad 

range of fire safety issues in collaboration with scientists and laboratories around the world. The 

Foundation is an affiliate of NFPA. 

About the National Fire Protection Association (NFPA) 

NFPA is a worldwide leader in fire, electrical, building, and life safety. The mission of the 

international nonprofit organization founded in 1896 is to reduce the worldwide burden of fire and 

other hazards on the quality of life by providing and advocating consensus codes and standards, 

research, training, and education. NFPA develops more than 300 codes and standards to minimize 

the possibility and effects of fire and other hazards. All NFPA codes and standards can be viewed 

at no cost at www.nfpa.org/freeaccess. 

Keywords: kitchen and cooking equipment, food and cooking materials, ranges, research report 

—— Page ii ——
 

—— Page iii ——
 

 

 

 

 

 

 

 

Steering Team 

Technologies to Mitigate Home Cooking Fires 

Rik Jonsson, National Institute for Standards and Technology 

Anthony Hamins, National Institute for Standards and Technology 

Bob Backstrom, Underwriters Laboratories 

Andrew Trotta, Consumer Product Safety Commission 

John Hall, NFPA 

Marty Ahrens, NFPA 

Pat Boyer, State Farm Insurance 

Amanda Robbins, Sereca Fire Consulting 

Wayne Morris, Association of Home Appliance Manufacturers 

Mike Love, Vision 20/20 

Karen Benedek, Primaira, Inc. 

—— Page iv ——
 

—— Page v ——
Development of Standardized Cooking Fires for Evaluation of Prevention Technologies: Data Analysis 

Prepared for 

Kathleen Almand
 

National Fire Protection Research Foundation
 

1 Batterymarch Park 

Quincy, MA 02169 

Prepared by 

Joshua B. Dinaburg and Dr. Daniel T. Gottuk 

Hughes Associates, Inc.
 

3610 Commerce Dr., Suite 817 

Baltimore, MD 21227
 

www.haifire.com
 

July 18, 2014 

FIRE SCIENCE & ENGINEERING 
STANDARD COOKING FIRES 1DTG02049.009 PAGE ii 

TABLE OF CONTENTS
 

EXECUTIVE SUMMARY......................................................................................................................... iv
 

1. BACKGROUND ................................................................................................................................ 1
 

2. OBJECTIVE ...................................................................................................................................... 1
 

3. SCOPE .............................................................................................................................................. 2
 

4. APPROACH ...................................................................................................................................... 2
 

5. TEST DESCRIPTION ........................................................................................................................ 3
 

5.1. Test Apparatus ................................................................................................................3
 

5.1.1. Collection Hood .....................................................................................................3
 

5.1.2. Instrumentation......................................................................................................4
 

5.2. Variables Evaluated ........................................................................................................9
 

5.2.1. Ranges and Cooktops ...........................................................................................9
 

5.2.2. Cooking Utensils..................................................................................................10
 

5.2.3. Cooking Oils ........................................................................................................13
 

5.3. Test Summary................................................................................................................14
 

5.4. Measures of Performance ............................................................................................18
 

5.4.1. Free Fatty Acid (FFA) Content ............................................................................18
 

5.4.2. Total Heating Time to Ignition..............................................................................18
 

5.4.3. Pan Temperature Thresholds..............................................................................18
 

5.4.4. Smoke Measurement ..........................................................................................19
 

5.4.5. Gas Measurements .............................................................................................20
 

5.4.6. Correlation ...........................................................................................................20
 

5.4.7. Instrumentation Comparison ...............................................................................21
 

6. TEST DATA..................................................................................................................................... 22
 

6.1. Phase 1 and Phase 2 Test Conditions.........................................................................22
 

6.1.1. Oil Temperature Measurement............................................................................23
 

6.1.2. Pan Size ..............................................................................................................24
 

6.1.3. Local Airflow Conditions ......................................................................................24
 

6.2. Free Fatty Acid Content ................................................................................................25
 

6.3. Oil Type .......................................................................................................................... 26
 

6.3.1. Available Response Times ..................................................................................28
 

6.3.2. Temporal Heating Curves....................................................................................31
 

6.3.3. Smoke Production and Ignition Temperatures ....................................................34
 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE iii 

6.4. Aged/Used Oil................................................................................................................38
 

6.4.1. Available Response Times ..................................................................................40
 

6.4.2. Temporal Heating Curves....................................................................................43
 

6.4.3. Smoke Production and Ignition Temperatures ....................................................44
 

6.5. Oil Brands ...................................................................................................................... 49
 

6.6. Pan Material ................................................................................................................... 52
 

6.6.1. Available Response Times ..................................................................................53
 

6.6.2. Temporal Heating Curves....................................................................................60
 

6.6.3. Smoke Production and Ignition Temperatures ....................................................63
 

6.7. Ranges ........................................................................................................................... 67
 

6.7.1. Range Power Level (Phase 1).............................................................................68
 

6.7.2. Range Type (Phase 2) ........................................................................................76
 

6.8. Oil Depth ........................................................................................................................ 86
 

6.8.1. Available Response Times ..................................................................................87
 

6.8.2. Temporal Heating Curves....................................................................................88
 

6.8.3. Smoke Production and Ignition Temperatures ....................................................92
 

6.9. Pan Thickness and Diameter .......................................................................................98
 

6.9.1. Available Response Times ................................................................................100
 

6.9.2. Temporal Heating Curves..................................................................................103
 

6.9.3. Smoke Production and Ignition Temperatures ..................................................107
 

6.10. Pan Warping and Temperature Overshoot ...............................................................113
 

7. GLOBAL TEST CORRELATIONS................................................................................................115
 

8. COMPARISON OF TEST INSTRUMENTATION ..........................................................................118
 

9. RECOMMENDATIONS FOR TEST STANDARD .........................................................................121
 

9.1.1. Test Scenarios ...................................................................................................121
 

9.1.2. Demonstration of Acceptable Test ....................................................................125
 

9.1.3. Prevention Device Performance Criteria ...........................................................127
 

9.1.4. Summary of Recommendations ........................................................................129
 

10. REFERENCES .............................................................................................................................. 130
 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE iv 

EXECUTIVE SUMMARY 

Cooking range top fires account for over 91,000 home fires each year, causing over 300 and 3,700 

annual deaths and injuries, respectively, based on data from 2006–2010 [1]. In addition, many cooking 

fire incident and injuries go unreported to fire departments and are not included within the data. 

Technologies potentially capable of preventing these fires have been considered and reviewed for the 

past 30 years. Beginning in 2010, Hughes started working with the Fire Protection Research 

Foundation (FPRF) to review the potential effectiveness of various technological options [2]. A 

workshop conducted as part of that project considered the emergence of commercial products on the 

market and identified the need to develop standardized tests and criteria to evaluate the performance 

and effectiveness of such devices. This report has summarized and analyzed the results of two live 

fire test series conducted to form the basis for such a test protocol. 

The tests conducted were intended to: 1) develop the basic protocols for conducting standardized tests; 

2) develop performance criteria for conduct of valid tests; and, 3) develop performance criteria for 

assessing fire protection performance of prevention technologies. The scope of this work was limited to 

assessing only fire preventing technologies, not those that would contain or alert after ignition. 

Fire tests were conducted to assess the pre-ignition conditions for cooking oils in pans on electric 

surface cooktops of ranges. The pan temperatures, oil temperatures, effluent temperatures, and gas 

concentrations were measured continuously from the start of heating until ignition. Tests evaluated the 

impacts of oil types, oil brands, oil age and usage, oil depth, pan materials, pan sizes and thicknesses, 

range power, and range type (glass ceramic radiant element and coil element). It was intended to 

identify the test conditions that would present the greatest potential challenges to prevention devices 

and select them for inclusion in the recommended standard testing. 

It was found that the type/age/use of oil only had a strong influence on the production of smoke, and 

not on the temperature of ignition. The percent free fatty acid (% FFA) of the oils tested were 

measured and correlated with the smoke and ignition temperatures. The % FFA varied for oils of 

different types (low for canola, vegetable, peanut oils, high for pork lard). The % FFA was also 

increased by artificially aging oils by sustaining them at high temperatures or using oils by repeatedly 

cooking food in them. Oils with increased % FFA produced smoke at lower temperatures, but ignited at 

approximately the same temperatures. Oils that produced smoke at lower temperatures were 

considered less challenging to detect before ignition. Fresh canola oil (lowest % FFA) was selected for 

continued testing and is recommended for a test standard. The brand of oil used (tested commercial 

grade and multiple consumer brands) did not affect the ignition properties, and no specific brand need 

be specified for testing. 

Numerous criteria were used to identify “challenging” scenarios. Some examples include: 1) the total 

heating time to reach ignition; 2) the window of time available between a fixed pan temperature 

threshold (e.g. 300 °C) and ignition, 3) the window of time available between a measured smoke 

obscuration (e.g. 1.6 %/ft) and ignition; 4) the temperature of the pan at ignition; and, 5) the 

temperature of the oil at ignition. In general, the total heating time and available fixed pan 

temperature/smoke obscuration windows scaled proportionally, and were decreased by increasing the 

element power, decreasing the oil depth/volume, reducing the pan mass/specific heat capacity, and 

increasing the pan/element contact area. Conversely, the measured pan and oil temperatures at 

ignition were reduced inversely with the length of the test, presenting potential challenges for tests 

taking long periods to reach ignition. 

The criteria used to identify challenging tests were directly related to the total heating time required to 

reach ignition. It is recommended that both fast and slow tests be conducted to challenge all potential 

detection technologies. The fastest tests ignited in less than 7 minutes of heating. The slowest tests 

required as much as 1 hour of heating before ignition occurred (if at all). Several combinations of test 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE v 

variables were capable of producing heating times in these ranges by varying the range power, oil 

depth, etc. If a prevention device requires the use of a specific test variable (e.g. pan type, range type, 

etc.), it should be possible to produce a fast or slow test including this condition. The specific 

conditions producing fast/slow ignitions need not be specified or limited for standardized testing. The 

slowest tests were much more variable, with ignition times ranging from 20 minutes to over 1 hour for 

the same test conditions. A second set of “slow” tests (15-20 minute heating times) were also included 

in the recommendations to potentially provide a slow test but with more consistent results. 

In order to demonstrate that a proposed test setup will meet the fast or slow test criteria, a heating test 

must be conducted without the prevention device activated or present. For safety reasons, the 

demonstration tests need not be conducted up to ignition. It has been proposed that the tests be run 

until an oil temperature of 350 °C (662 °F) has been reached and then the heating source turned off. 

Acceptable boundaries for allowable pan and oil temperatures and smoke obscuration have been 

developed from the test data for fast, slow, and the slowest test cases. 

Pan and oil temperatures were measured in multiple locations in the tests conducted. Data showed 

that pan and oil temperatures measured at the center of the pan and at half of the initial oil depth above 

the pan surface provide a good representation of the spatial average. The oil temperature did not vary 

by more than 1–2 °C (3–4 °F) as a function of depth, and placement of the oil temperature 

measurement at the half oil depth (±1/16 inch) should be adequate for standardized testing. 

The smoke obscuration need only be measured and demonstrated within the test bounds if the 

prevention device to be tested uses smoke as an activation criteria. The current test design measured 

the smoke in a 4 ft x 4 ft hood over the range. Evaluation of real smoke measuring devices would 

require a more realistic kitchen type installation to provide the proper smoke concentrations for 

activation. Development of a smoke test room has not been evaluated as part of this effort and will 

require subsequent analysis. 

Performance criteria has been developed to evaluate the performance of prevention devices based on 

proposed limits to the measured oil temperature in the pan. For the tests utilizing the final 

recommended instrumentation, ignitions did not occur until the oil temperatures reached 374–406 °C 

(705–763 °F) and pan temperatures reached 385–432 °C (725–810 °F). Based on the available test 

data a threshold in the range of 300 to 350 °C (572 to 662 °F) should be sufficient for prevention of 

ignition. If a more conservative threshold is desired, such as 250 °C (482 °F) oil temperature, the 

minimum time to ignition increases to 130 seconds and the resulting pan surface temperatures 

decrease to 263–312 °C (505–594 °F). An oil temperature threshold of 300 °C is currently used by the 

Japanese Industrial Standard (JIS) 2103 and 2093 [6,7]. 

Some cooking methods may require the temperature of foods to reach as high as 260 °C (500 °F) [9]. 

Inclusion of a minimum oil temperature prevents devices from severely limiting the ability to cook. It is 

also suggested to include a maximum allowable deviation in heating rate. Tests conducted without the 

device operating (demonstration of acceptable fast/slow test) must heat the pan and oil within specified 

bounds. The inclusion of the device should not reduce the heating rate by more than a defined 

threshold, for example, 10% of the average temperature increase per minute. 

The recommendations for the performance criteria would include a device that can: 1) operate after the 

desired minimum oil temperature is reached; 2) operate before the maximum oil temperature is 

reached; and, 3) does not drastically reduce the heating rate measured without the device present, it 

should be considered acceptable. These three criteria would be required for achieving a passing test 

result. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 1 

1. BACKGROUND 

Cooking-equipment related fires are a leading cause of U.S. fire loss. The National Fire Protection 

Association (NFPA) reports that in 2006–2010, there were 157,300 annual average reported home 

cooking related fires per year (42% of all reported home fires), with associated annual losses of 380 

civilian deaths (15% of home fire deaths), 4,920 civilian injuries (38% of home fire injuries), and $794 

million in direct property damage (11% of home fire damages). Fires involving range tops accounted for 

58% of these cooking equipment fire incidents and 87% and 76% of the deaths and injuries, 

respectively [1]. 

Beginning in the mid-1980s, the National Institute of Standards and Technology (NIST), Consumer 

Product Safety Commission (CPSC), and the home appliance industry undertook a comprehensive 

review of strategies to mitigate death, injury and property loss from cooking fires. All approaches were 

engineering strategies defined by a condition to be detected (e.g., overheat of pan or food in pan, 

absence of person actively engaged in cooking process, early-stage fire on stovetop) and an action to 

be taken (e.g., shut off cooking heat, sound alarm, suppress fire). As part of this study, a comprehensive 

review of existing technologies was done [2]. 

In February of 2010, a Vision 20/20 workshop on this topic was convened in Washington DC. 

Participants recommended that a study be undertaken to identify the barriers to the utilization of these 

technologies and to develop an action plan towards improving cooking fire safety. 

In 2010, Hughes Associates, Inc. conducted a study for the Fire Protection Research Foundation 

(FPRF) supported by NIST to develop this action plan [2]. The study focused particularly on prevention 

technologies suitable for use on or with home electric and gas cooktops. and consisted of a literature 

and technology review; the development of an enhanced technology evaluation methodology based on 

an in-depth review of cooking fire statistics; and the evaluation of currently available technologies using 

this methodology. The project culminated with a one day workshop of 35 leaders from the kitchen 

appliance, fire service, and user communities who met to review the above findings and identify gaps in 

information. The highest priority action item identified at that workshop toward implementation of 

commercially available cooking fire mitigation technologies was: 

“Develop standard fire scenarios and create test methods and performance criteria which can 

feed into standards development” 

Toward this end, NIST funded a project through the FPRF conducted by Hughes, consisting of two 

series of tests evaluating various cooking fire scenarios (referred to in this report as Phase 1 and Phase 

2). The first phase evaluated the ignition characteristics for a range of cooking scenarios, including oils 

types, simulated oil aging, heating power, and pan size and thicknesses on electric coil elements. The 

second phase built on the initial tests to establish repeatability and to evaluate the impacts of used oils, 

various pan materials, oil depths, and glass ceramic radiant element cooktops on ignition 

characteristics. This report includes an evaluation of test data from both phases to quantify the impacts 

of the test variables, identify scenarios challenging to potential detection equipment, and 

recommendations for a standardized test. The standardized test includes procedures, criteria for 

conduct of valid tests, and criteria for evaluation of prevention devices. 

2. OBJECTIVE 

The primary objectives of the project were to: 

1. Develop the basis for standardized tests for evaluation of range top cooking fire prevention 

technologies. 

2. Develop performance criteria for conducting valid tests. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 2 

3. Develop performance criteria for assessing the fire protection performance of prevention 

technologies tested to the standard. 

3. SCOPE 

This project was limited to developing tests for evaluation of automatic fire prevention technologies for 

use on cooking range tops. Devices utilizing suppression, notification, user intervention, flame 

containment, etc. were not considered in the test development. 

Tests evaluated a range of potential ignition scenarios, with different types of ranges, pans, and oils. It 

is the intent to use this test data to select standardized scenarios based on repeatability, ignition 

properties, and applicability to prevention technologies. 

Although smoke obscuration was measured during this series of tests, the apparatus used does not 

represent a realistic kitchen environment. The smoke levels measured provide comparative information 

identifying when smoke is produced, the temperatures of the pan and oil at the time smoke is produced, 

and the relative amount of smoke produced for each tested scenario. Smoke was collected in a small 

hood enclosure resulting in much higher concentrations than expected for real cooking environments. 

Although the fire sources and procedures are appropriate, the hood enclosure would not be appropriate 

for evaluating the operation of a smoke operated control device for preventing range fires. 

4. APPROACH 

Full-scale testing was conducted using commercially available cooktops and cookware. Testing 

included the heating of various animal fats and plant derived oils to the point of flaming ignition. The 

term oil generally refers to any viscous liquid that is immiscible with water. In this report, the term oil is 

used to refer to any fat derived from a plant or animal that is used in cooking. This includes fats that are 

generally solid at room temperatures, including pork lard or beef shortening. Testing included both pure 

oils with no solid food use and oils that have been used for actual cooking of food. The oils were 

characterized by testing the free fatty acid (FFA) content. This oil property has been previously 

identified to correlate to the temperature of smoke production and ignition [3]. 

The temperatures of the pans, oils, and air, as well as the smoke and gas emissions were measured 

during heating to the point of ignition. This data was used to identify the conditions leading up to 

ignitions that may present challenges for initiation of automatic prevention devices. The most 

challenging scenarios are the leading candidates for use in standardized evaluation testing. The 

conditions leading up to ignition were also used to identify performance criteria for evaluating devices 

subjected to the proposed standardized testing. 

The impact of several factors on ignition conditions were assessed during testing. Variables included: 

1. Cooktop power and coil design 

2. Electric coil and glass ceramic radiant element range elements 

3. Pan sizes and thicknesses 

4. Pan materials 

5. Pan flatness 

6. Cooking oil type 

7. Cooking oil age/usage 

8. Oil depth 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 3 

5. TEST DESCRIPTION 

5.1. Test Apparatus 

A cooking fire test apparatus was constructed in the Hughes laboratory in Baltimore, MD. The 

apparatus consisted of an electric cooking range with cooktop placed beneath an enclosed collection 

hood. Pans were instrumented to measure temperature of the pan and the oil. The smoke and gases 

emitted by the heated oils were collected and measured inside the hood above the range. 

5.1.1. Collection Hood 

Testing was conducted with a range placed beneath a 4 ft x 4 ft x 1 ft (1.2 x 1.2 x 0.3 m) deep sheet 

metal collection hood. The hood was centered above the tested pan and located 3 ft (0.9 m) above the 

surface of the range. The collection hood did not have any duct work or mechanical means for 

removing the products of combustion. By eliminating a forced air flow duct connected to the hood, the 

fire effluent measurements are not dependent on the flow rate through the duct; hence, this should lead 

to a higher degree of reproducibility from test to test and lab to lab. 

The collection hood setup is shown in Figure 1. The heated pan effluent collected in the hood, creating 

a smoke layer that descended lower in the hood over time. When the layer descended below the 1 ft 

(0.3 m) depth of the hood, it spilled directly in to an open, ventilated space to remove the products of 

combustion from the test area. In Phase 1 testing, the open space was a 16 ft x 16 ft x 12 ft (4.9 x 4.9 x 

3.7 m) high room with a 1 x 1 ft (0.3 x 0.3 m) exhaust opening drawing approximately 600 ft3/min (17 

m3/min) of air. In Phase 2 testing, the apparatus was placed beneath a 10 ft x 10 ft (3.0 x 3.0 m) 

exhaust hood continuously drawing approximately 7000 ft3/min (198 m3/min). In both test conditions, 

the effluent from the pan was observed to rise naturally into the collection hood until it spilled over. 

Neither condition produced a cross-flow that pushed effluent away from the hood, and the conditions 

were deemed approximately equivalent. The effects of the local airflow conditions are compared in 

detail in Section 6.1.3. 

Figure 1 – Collection hood and range setup 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 4 

5.1.2. Instrumentation 

Continuous temperature and voltage measurements were recorded during testing by a National 

Instruments cDAQ-9174 compact data acquisition chassis. Temperatures were measured using a 

cDAQ-9214 thermocouple module and voltages were measured using a cDAQ-9205 ±10 V voltage 

module. Data was recorded by a Labview program at a rate of 1 Hz (Phase 1) or 2 Hz (Phase 2) during 

fire tests. 

5.1.2.1. Cooktop Power 

The cooktop power was measured by continuous current measurement during fire testing. The voltage 

supplied to the cooktop under test was measured prior to testing using an Omega multi-meter. The 

current was measured continuously by an Eaton EACP1420120SP AC current sensor. The voltage and 

current were multiplied to determine the wattage draw of the element during testing. 

5.1.2.2. Pan Temperature 

Pan temperatures were measured continuously during fire tests using 24 gauge fiberglass sheathed 

type K special limit of error (±1.1°C or 0.4%, whichever is greater) thermocouples welded to the top 

surface of the pan. Beads were welded at the ends of the wires by a TIGTECH 116SRL thermocouple 

welder with argon purge. The beads were then attached to the pan surface using a DCC Corporation 

HotSpot TC Welder. 

Three thermocouples were placed in each pan at the center and along an axis with the handle, located 

1 in. (2.5 cm) from the outside of the pan base. The pan thermocouple locations are shown in Figure 2. 

Figure 2 – Pan thermocouple measurement locations 

5.1.2.3. Oil Temperature 

Oil temperatures were measured continuously using type K thermocouples with welded beads. During 

Phase 1 testing, beads were welded at the ends of 24 gauge fiberglass sheathed wires special limit of 

error (±1.1°C or 0.4%, whichever is greater) using a TIGTECH 116SRL thermocouple welder with argon 

purge. The exposed beads were approximately 0.8 in. (2 mm) in size and inserted into the oil. During 

Phase 2 testing, the oil temperatures were measured using Inconel sheathed, 0.020 in. (0.5 mm) 

grounded thermocouples (Omega KMQIN-020G-18, ±2.2°C or 0.75%, whichever is greater). These 

thermocouples were smaller in size and easier to place at the desired oil depths. The response time of 

the smaller, yet shielded thermocouples was found to be shorter. The thermocouples were 

simultaneously plunged into a cup of hot water (~50°C), and the Inconel sheathed thermocouples 

reached steady state temperatures approximately 2 seconds faster than the 24 gauge welded beads. In 

addition, the Inconel was much easier to clean between fire tests, improving the efficiency of the test 

procedures. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 5 

The oil temperature measurement locations are shown in Figure 3. Nine thermocouples were placed in 

each pan at three locations each at three depths. The oil temperatures were measured along an axis 

perpendicular to the pan handle located 3⁄4 of the pan base from the handle. The temperature was 

measured along the center line of the pan and 1/3 of the pan diameter to either side of the center axis. 

At each location, the oil temperature was measured at half the depth of the oil. For tests with a 1⁄4 in. (6.3 mm) 

oil depth, the thermocouples were placed at a depth of 1/8 in. (3.2 mm). Additional measurements were 

made at each location 1/32 in. (0.8 mm) above and below half the oil depth (3/32 and 5/32 in. (2.4 mm 

and 4.0 mm)). For tests with a 1⁄2 in. (12.7 mm) oil depth, the TCs were placed at depths of 1⁄4 in. (6.3 mm) ± 

1/8 in. (3.2 mm). The additional vertical measurements were conducted to assess the sensitivity of the 

measured oil temperature to the thermocouple depth in order to properly specify a standard test setup. 

Oil thermocouple locations – Side view 

Oil thermocouple locations – Front view 

Figure 3 – Oil temperature measurement locations for 1⁄4 in. (6.3 mm) oil depths 

The oil thermocouple beads were held in place by clamping the wires between two aluminum bars 

resting on angled feet inside the pan. The two clamping bars were cut to a length 2 in. (5.1 cm) shorter 

than the pan diameter. The feet consisted of two pieces of 1⁄4 in. (6.4 mm) thick aluminum angle cut to 

1⁄4 in. (6.4 mm) widths. The two clamping bars were then screwed to the feet such that the bottom of the 

bars sat 1⁄4 in. in. (6.4 mm) above the base of the feet. This provided a fill line to ensure 1⁄4 in. (6.4 mm) 

of oil had been used in each test and kept the thermal mass of the bars outside of the tested oil. The 

thermocouple wires were run between the two bars and the screws were tightened to keep the beads in 

place. The TC depths were measured prior to each test by sliding a small steel bar with a thickness at 

the desired depth beneath the TC and adjusting until the TC just contacted the bar. Photographs of a 

pan with the aluminum mounting bars and the pan thermocouples, including a close up view of the 

mounting bar are shown in Figure 4 for Phase 1 (24 gauge exposed beads) and Figure 5 (Inconel 

sheathed). 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 6 

Figure 4 – Thermocouple measurements and mounting bar in test pan (Phase 1) 

Figure 5 – Thermocouple measurements and mounting bar in test pan (Phase 2) 

5.1.2.4. Effluent Temperature 

The gas temperature in the hood was measured using 24 gauge fiberglass sheathed type K 

thermocouples with welded beads. Beads were welded at the ends of the wires by a TIGTECH 116SRL 

thermocouple welder with argon purge. 

Thermocouples were uniformly spaced in the collection hood 2 in. (5.1 cm) below the top of the hood. 

The thermocouples were each located in the center of a quadrant of the hood, located 12 in. (30 cm) 

from the walls and 24 in. (61 cm) from the adjacent thermocouples. The effluent thermocouple locations 

are shown with the smoke and gas concentration measurements in the hood diagram in Figure 6. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 7 

5.1.2.5. Smoke Concentration 

Smoke concentrations were measured in the collection hood through laser light extinction 

measurements. Two ThorLabs CPS186, 670 nm, 4.5 mW lasers were mounted to the outside of the 

collection hood pointing down parallel axes 3 in. (7.6 cm) below the top of the hood and 12 in. (30 cm) 

from either side. The laser beam paths and installation locations are shown in Figure 5. The lasers 

were powered by an EPSCO Model D-612T Filtered DC Power Supply at a constant 5 V. The laser 

intensity was measured on the opposite side of the collection hood by PDA36A amplified SI photodiode 

detectors with variable gain and sensitivity to 350-1100 nm light. The smoke concentration over the 4 ft 

(1.2 m) path lengths were recorded as both optical density and obscuration per foot by comparing the 

intensity of laser light on the photodiodes prior to and during fire testing. 

The operation of the laser obscuration meters were verified using ThorLabs NG11 Schott Glass neutral 

density filters. The filters were placed in the beam path and the resulting obscurations and optical 

densities were calculated and confirmed. The lasers were verified using filters with optical densities at 

670 nm of 0.112, 0.298, 0.374, 0.945, 1.838, and 2.732. 

5.1.2.6. Gas Concentrations 

Gas concentrations, including oxygen (O2), carbon dioxide (CO2), and carbon monoxide (CO), were 

measured in the collection hood. Gas samples were drawn and mixed from four locations in the hood, 

at the center of each quadrant and a distance of 1 in. (2.5 cm) below the top of the hood as shown in 

Figure 6. The gas samples were analyzed for concentration by a Horiba VA-3000 paramagnetic oxygen 

analyzer (reporting accuracy of 0.01% O2, repeatability of 0.125% O2), a Horiba VIA-510 infrared 

carbon dioxide analyzer (reporting accuracy of 0.001% CO2, repeatability of 0.025 %CO2), and a 

Rosemount Analytical Model 880A infrared carbon monoxide analyzer (reporting accuracy of 1 ppm 

CO, repeatability of 10 ppm CO). Analyzers were zeroed and spanned to full ranges daily prior to 

testing. Transport time delays were measured until 90% of known concentrations were reported using 

calibration gases introduced at the sampling ports. Transport times (t90) between 45 and 60 seconds 

were measured when the setup was located in the enclosed room (Phase 1) and approximately 30 

seconds when beneath the exhaust hood (Phase 2). These delay times were accounted for in the 

presented test data. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 8 

Top

 Fron

 Righ 

Figure 6 – Temperature, smoke, and gas measurements in the collection hood 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 9 

5.2. Variables Evaluated 

5.2.1. Ranges and Cooktops 

Test fires were initiated using open coil electric and glass ceramic radiant range heating elements. A 

GE JBP23DRWW and a Frigidaire FFEF3011 LW were selected as the open coil electric ranges for 

testing due to differences in heat output and element coil surface area/shape. A GE JBS60DFWW 

glass ceramic range was selected based on input from the steering team and due to the 3000 W power 

boil element. Tests were conducted on the 8 in. (20 cm), 2600 W, 6 turn coil and the 6 in. (15 cm), 1500 

W, 4 turn coil on the GE range. Tests were also conducted on the 8 in. (20 cm), 2100 W, 4 turn coil on 

the Frigidaire range. Tests were conducted with the element power turned on to the highest setting, 

except for several tests conducted on the 8 in. (20 cm) GE coil element where the power was matched 

to the 2100 W of the Frigidaire coil element for direct comparison of the element shape. The ranges 

and elements tested are shown in Figure 7. 

GE JBP23DRWW Range GE 2600 W 8 inch 6 turn co GE 1500 W 6 inch 4 turn coi 

Frigidaire FFEF3011LW Range Frigidaire 2100 W 8 inch 4 turn coil 

GE JBS60DFWW Range GE 3000W power boil element 

Figure 7 – Range tops and elements used during testing 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 10 

All three ranges required 240 VAC power. Power was provided by a Staco 5021CT-2S variable control 

AC transformer with 480 V input set and verified daily to provide 240 V ±1 V to the ranges tested. The 

voltage was measured prior to the start of each test day using a handheld voltmeter. The current drawn 

by the ranges was measured continuously during testing to determine the power output of the 

elements. When the power level on a element was reduced from maximum, the power was observed to 

cycle on and off, and the numeric power setting was related to the duration of on-cycles. The power 

was reduced on the GE coil element range by matching the element on cycling time to the desired 

power ratio, in this case 2100 W/2600 W. Therefore, the element power cycled on 81% of the time 

during the reduced power testing. 

Even at the highest power setting, the glass ceramic range was observed to cycle power after the glass 

temperatures reached elevated levels. This power cycling was measured and recorded, and while 

ignition times were potentially delayed, ignitions were still observed to occur for these cooktops. 

5.2.2. Cooking Utensils 

Cookware used during testing included solid aluminum fry pans of varying thicknesses (5–10 gauge) 

and diameters (7–14 in. (18-36 cm)). According to the Cookware Manufactures Association (CMA), 

aluminum pans represent the majority (approximately 70%) of consumer products, and the selection of 

a single pan material allowed for evaluation of other variables that may impact ignition. For consistency 

and reproducibility, the evaluated pans were solid aluminum only and did not contain any non-stick 

coating and were not anodized. Additional tests were conducted using a Tramontina Everyday 

Stainless Steel sauté pan, an All-Clad 4110 Tri-Ply bonded stainless steel pan, and a Lodge LCS3 cast 

iron Chef’s skillet. Due to the variability and uncertainty of construction of stainless steel pans, the two 

steel pans selected were chosen to represent a range of low-end (Tramontina ~$20) and high-end (AllClad ~$120) pans. A summary of the pans tested is shown in Table 1. No pan gauge thicknesses were 

provided with the stainless steel or cast iron pan, and the reported thicknesses have been measured. 

Exemplar photographs of 8 gauge, 10 in. (25 cm) diameter pan, the two stainless steel pans, and the 

cast iron pan are shown in Figure 8. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 1 – Frying pans tested 

Pan ID Material Manufacturer Brand Model Gauge Thickness 

(in.) 

Diameter 

(in.) (cm) 

AL-BH-8-5 

Aluminum Browne-Halco Thermalloy 

14808 5 0.1819 (4.6 mm) 8 20 

AL-BH-10-5 14810 10 25 

AL-BH-8-8 13808 

8 0.1285 (3.3 mm) 8 20 

AL-BH-10-8 13810 10 25 

AL-BH-14-8 13814 14 36 

AL-V-7-8 

Aluminum Vollrath 

Wear-Ever 67907 

8 0.1285 (3.3 mm) 7 18 

AL-V-10-8 Arkadia 7010 10 25 

AL-V-14-8 7014 14 36 AL-V-8-10 Wear-Ever 4008 10 0.1019 (2.6 mm) 8 20 

AL-V-10-10 4010 10 10 25 

SS-T-10 Stainless 

Steel 

Tramontina Everyday NA NA 0.135 (3.4 mm) 10 25 

SS-AC-10 All-Clad Tri-Ply 4110 NA 0.19 (4.8 mm) 10 25 

CI-L-10 Cast Iron Lodge NA LCS3 NA 0.21 (5.3 mm) 10 25 

NA – Not available from product literature at time of purchase 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 12 

Aluminum pans 

Tramontina Stainless Steel All-Clad Stainless Steel 

Lodge Cast Iron 

Figure 8 – Exemplar frying pans used during testing 

Cookware was only reused after a fire test if all solid material could be removed by cleaning and the 

flatness of the bottom of the pan remained within 0.006 times the pan diameter. This was considered 

the minimum amount of deviation in flatness that may impact test results. This level of flatness was 

selected in accordance with the flatness specifications included in UL 1026 41.2.9.1 [4]. The flatness 

was measured by placing a flat steel bar across the bottom of the pan and measuring the separation 

between the pan bottom and bar in three locations along two orthogonal axes. Measurements were 

made at the center and radial distances of 2 in. (5.1 cm). If the difference between any two of the six 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 13 

measurements exceeded 0.006 times the pan diameter, the pan was considered unacceptable. No pan 

was observed to exceed this allowance after repeated fire testing. 

Additional testing was conducted to evaluate the ability to warp a pan using thermal cycling. A dry 10 

gauge, 8 in. (20 cm) diameter pan was heated (with no contents) on the 8 in. (20 cm) GE electric coil 

element until the pan temperature measured approximately 750°F–840°F (400°C–450°C). All power 

was then cutoff to the element and duration and magnitude of any potential temperature overshoots 

were measured. When the temperature began to decrease it was dunked into a large water tank to 

initiate rapid cooling. This process was repeated through 30 heating and cooling cycles. The use of 

cookware with non-flat bottoms may impact the performance of a fire prevention device intended to 

make a contact temperature measurement with the bottom of the pan. In addition, these tests also 

quantified the degree of temperature overshoots that may occur after turning off the element. 

5.2.3. Cooking Oils 

Tests were conducted using both pure cooking oils without solid food products and oils previously used 

to cook foods. The intent of the overall project was to develop consistent standardized tests, and the 

use of solid food would likely increase the variability and uncertainty in the test results. If, however, the 

use of oil with food was found to increase the challenge for fire prevention, this type of source would 

require inclusion in the test standard. Various formulations of cooking oils were used including both 

plant and animal fats. Commercial brand oils purchased from industrial suppliers were tested and 

compared to consumer brand (off the shelf) oils. Evaluated oils were selected from the most common 

cooking applications and included: 

 Soybean (vegetable) oil 

 Corn oil 

 Canola oil 

 Peanut oil 

 Beef shortening 

 Pork lard 

The beef shortening and pork lard were solid fats at room temperatures. In order to pour the oils to a 

consistent depth for testing, these oils were preheated in a separate pot to a temperature of 35°C 

(95°F) and melted. The liquids were then poured to a test depth of 1⁄4 in. (6.4 mm) and testing 

conducted without allowing the liquid to re-solidify. 

Consumer brand oils tested included Wesson, Crisco, Great Value, and a generic brand soybean 

(vegetable) and canola oils, and Morrell Snow Cap Pork Lard. All oils subjected to fire tests were 

analyzed for the FFA content by an external testing laboratory. This component of cooking oil has been 

reported to be inversely correlated with the auto-ignition temperature and smoke point [3]. It was 

recommended by the American Oil Chemists’ Society (AOCS) to use FFA to characterize the various 

oil types tested. 

In order to evaluate the potential impacts of used oil on ignition parameters, the commercial oils tested 

were artificially “aged” by maintaining a pot of oil at 204°C (400°F ) for a total of 8 continuous hours in 

Phase 1 testing. Fire tests and FFA analyses were conducted on the aged oils to determine the 

potential impacts on ignition conditions. In addition to the artificially aged oils, a sample of used 

soybean (vegetable) oil was obtained from a fast food restaurant. The oil was used throughout 

lunchtime to cook french fries and chicken nuggets and was included to represent a scenario for heavily 

used oils. 

In Phase 2 testing, samples of vegetable oil and pork lard were subjected to repeated cooking cycles to 

simulate home usage. One gallon (3.78 L) of each oil was placed into a large cookpot on a ceramic 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 14 

heating plate. The oil temperatures were raised to 204°C (400°F) and food was added to the pots. The 

food consisted of 3 lb (1.36 kg) of chicken thighs rolled in white flour, eggs, and seasoned bread 

crumbs. The addition of the cool chicken lowered the oil temperature to approximately 165°C (330°F) 

and the chicken was cooked for 20 minutes and removed. After cooking, the oil was allowed to cool 

naturally in the cookpot and then all solid material was removed using a fine kitchen strainer (Mainstays 

American Housewares 8” Food Strainer). After returning to room temperature, the process was 

repeated (typically a day or two later) until the oil was deemed unusable due to odor or color. This was 

found to occur after 10 cooking cycles with the pork lard and 12 cooking cycles with the vegetable oil. 

The color of oils between every two cooking cycles is shown in Figure 9. 

Figure 9 – Appearance of oils used for frying chicken, pork lard (top) and vegetable oil (bottom) 

These tests were included due to concerns that residential cooking performed with used oils may 

present an increased hazard of ignition compared to cooking with fresh oil. This would present an 

additional challenge for a prevention device and was therefore considered for development of a 

standardized test. 

Fire tests were conducted by pouring 1⁄4 in. (6.4 mm) of oil into each pan evaluated. This depth of oil 

was used to minimize test time and was found to produce consistent ignition in all tests while providing 

sufficient depth to allow for insertion of temperature probes into the oil without contacting the surface of 

the pan. Additional tests were conducted during Phase 2 to evaluate the impact of 1⁄2 in (12.7 mm) oil 

depths. 

5.3. Test Summary 

A summary of all tests conducted in both Phase 1 and Phase 2 of the analysis is shown in Table 2. All 

Phase 2 tests were conducted in triplicate, and are organized according to the scenarios tested. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 2 – Summary of tests conducted 

PHASE 1 TESTS 

Test ID Pan ID 

Oil Range 

Type Brand Condition 

Depth 

(in) Type 

P1-1 AL-BH-8-8 Soybean Commercial Fresh 0.25 GE Coil 

P1-2 AL-BH-8-8 Corn Commercial Fresh 0.25 Coil P1-3 AL-BH-8-8 Corn Commercial Fresh 0.25 Coil P1-4 AL-BH-8-8 Corn Commercial Fresh 0.25 Coil P1-5 AL-BH-8-8 Canola Commercial Fresh 0.25 GE Coil 

P1-6 AL-BH-8-8 Canola Commercial Fresh 0.25 GE Coil 

P1-7 AL-BH-8-8 Peanut Commercial Fresh 0.25 GE Coil P1-8 AL-BH-8-8 Beef Shortening Commercial Fresh 0.25 GE Coil 

P1-9 AL-BH-8-8 Pork Lard Commercial Fresh 0.25 GE Coil P1-10 AL-BH-8-8 Soybean Crisco Fresh 0.25 GE Coil 

P1-11 AL-BH-8-8 Canola Crisco Fresh 0.25 GE Coil P1-12 AL-BH-8-8 Soybean Wesson Fresh 0.25 GE Coil 

P1-13 AL-BH-8-8 Canola Wesson Fresh 0.25 GE Coil P1-14 AL-BH-8-8 Soybean Commercial Aged 0.25 GE Coil 

P1-15 AL-BH-8-8 Corn Commercial Aged 0.25 GE Coil 

P1-16 AL-BH-8-8 Canola Commercial Aged 0.25 GE Coil 

P1-17 AL-BH-8-8 Peanut Commercial Aged 0.25 GE Coil 

P1-18 AL-BH-8-8 Lard Commercial Aged 0.25 GE Coil 

P1-19 AL-BH-8-8 Soybean Commercial Useda 0.25 GE Coil 

P1-20 AL-BH-8-8 Soybean Commercial Fresh 0.25 Frigidaire Coil 

P1-21 AL-BH-8-8 Canola Commercial Fresh 0.25 Frigidaire Coil P1-22 AL-BH-8-8 Soybean Commercial Fresh 0.25 GE Coil 

P1-23 AL-BH-8-8 Canola Commercial Fresh 0.25 GE Coil P1-24 AL-BH-8-8 Canola Commercial Fresh 0.25 GE Coil P1-25 AL-V-7-8 Canola Commercial Fresh 0.25 GE Coil 

P1-26 AL-V-7-8 Soybean Commercial Fresh 0.25 GE Coil 

P1-27 AL-V-14-8 Canola Commercial Fresh 0.25 GE Coil 

P1-28 AL-V-14-8 Soybean Commercial Fresh 0.25 GE Coil 

P1-29 AL-BH-8-5 Corn Commercial Fresh 0.25 GE Coil 

P1-30 AL-BH-8-5 Lard Commercial Fresh 0.25 GE Coil 

P1-31 AL-V-8-10 Corn Commercial Fresh 0.25 GE Coil 

P1-32 AL-V-8-10 Lard Commercial Fresh 0.25 GE Coil 
STANDARD COOKING FIRES 1DTG02049.009 

PHASE 2 TESTS 

Scenario Test ID Pan ID (Table 1) Oil Range Type Brand Condition Depth (in) Type 

1 

P2-1 AL-V-10-8 Soybean Great Value Fresh 0.25 GE Coil 

P2-2 AL-V-10-8 Soybean Great Value Fresh 0.25 GE Coil P2-3 AL-V-10-8 Soybean Great Value Fresh 0.25 GE Coil 

2 

P2-4 AL-V-10-8 Canola Great Value Fresh 0.25 GE Coil 

P2-5 AL-V-10-8 Canola Great Value Fresh 0.25 GE Coil P2-6 AL-V-10-8 Canola Great Value Fresh 0.25 GE Coil 

3 

P2-4a AL-BH-10-8 Canola Great Value Fresh 0.25 GE Coil 

P2-5a AL-BH-10-8 Canola Crisco Fresh 0.25 GE Coil 

P2-6a AL-BH-10-8 Canola Generic Fresh 0.25 GE Coil 

4 

P2-7 AL-BH-10-8 Lard Morrell Fresh 0.25 GE Coil 

P2-8 AL-BH-10-8 Lard Morrell Fresh 0.25 GE Coil 

P2-9 AL-BH-10-8 Lard Morrell Fresh 0.25 GE Coil 

5 

P2-10 AL-V-10-8 Soybean Great Value Used 0.25 GE Coil P2-11 AL-V-10-8 Soybean Great Value Used 0.25 GE Coil P2-12 AL-V-10-8 Soybean Great Value Used 0.25 GE Coil 

6 

P2-13 AL-BH-10-8 Lard Morrell Used 0.25 GE Coil 

P2-14 AL-BH-10-8 Lard Morrell Used 0.25 GE Coil 

P2-15 AL-BH-10-8 Lard Morrell Used 0.25 GE Coil 

7 

P2-16 SS-T-10 Canola Great Value Fresh 0.25 GE Coil P2-17 SS-T-10 Canola Wesson Fresh 0.25 GE Coil P2-18 SS-T-10 Canola Crisco Fresh 0.25 GE Coil 

8 

P2-19 SS-AC-10 Canola Great Value Fresh 0.25 GE Coil 

P2-20 SS-AC-10 Canola Wesson Fresh 0.25 GE Coil 

P2-21 SS-AC-10 Canola Crisco Fresh 0.25 GE Coil 

9 

P2-22 CI-L-10 Canola Wesson Fresh 0.25 GE Coil P2-23 CI-L-10 Canola Crisco Fresh 0.25 GE Coil 

P2-24 CI-L-10 Canola Great Value Fresh 0.25 GE Coil 

10P2-25 AL-V-10-8 Canola Great Value Fresh 0.25 Glass Ceramic 
STANDARD COOKING FIRES 1DTG02049.009 

P2-26 AL-V-10-8 Canola Wesson Fresh 0.25 Glass Ceramic 

P2-27 AL-V-10-8 Canola Crisco Fresh 0.25 Glass Ceramic 

P2-25ad AL-V-10-8 Canola Great Value Fresh 0.25 Glass Ceramic 

11 

P2-28 SS-AC-10 Canola Great Value Fresh 0.25 Glass Ceramic 

P2-29 SS-AC-10 Canola Generic Fresh 0.25 Glass Ceramic 

P2-30 SS-AC-10 Canola Crisco Fresh 0.25 Glass Ceramic 

12 

P2-31 CI-L-10 Canola Great Value Fresh 0.25 Glass Ceramic 

P2-32 CI-L-10 Canola Generic Fresh 0.25 Glass Ceramic P2-33 CI-L-10 Canola Crisco Fresh 0.25 Glass Ceramic 

13 

P2-37 AL-V-10-8 Canola Crisco Fresh 0.50 GE Coil P2-38 AL-V-10-8 Canola Great Value Fresh 0.50 GE Coil 

P2-39 AL-V-10-8 Canola Wesson Fresh 0.50 GE Coil 

14 

P2-40 SS-T-10 Canola Great Value Fresh 0.50 GE Coil 

P2-41 SS-T-10 Canola Wesson Fresh 0.50 GE Coil 

P2-42 SS-T-10 Canola Wesson Fresh 0.50 GE Coil 

15 

P2-34 AL-BH-10-5 Canola Great Value Fresh 0.25 GE Coil P2-35 AL-BH-10-5 Canola Wesson Fresh 0.25 GE Coil P2-36 AL-BH-10-5 Canola Generic Fresh 0.25 GE Coil 

16 

P2-43 AL-BH-14-8 Canola Great Value Fresh 0.25 GE Coil 

P2-44 AL-BH-14-8 Canola Wesson Fresh 0.25 GE Coil 

P2-45e AL-BH-14-8 Canola Wesson Fresh 0.25 GE Coil 

a – Used oil obtained from fast food restaurant deep fryer b – 2100 W obtained by lowering level to 8.75 power setting on 2600 W range c – 1500 W obtained from small element on GE coil range d – Repeat test conducted with brand new pan to verify results of test P2-25 e – Ignition did not occur after 1 hour of heating, stopped test 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 18 

5.4. Measures of Performance 

Data taken during testing provided transient growth profiles for temperature, smoke, and gas 

concentrations during heating and up to the point of flaming ignition. In addition to the temporal 

variations, spatial variations in temperature were measured on the pan surface, in the cooking oil, and 

in the effluent. Smoke concentrations were measured at two symmetric locations within the collection 

hood. This data has been processed and condensed to provide several measures of performance for 

each test conducted. These measures are intended to provide representative values for comparison of 

various test scenarios and to identify variability among repeat test scenarios. 

5.4.1. Free Fatty Acid (FFA) Content 

For each test conducted, the oil used was subjected to a FFA evaluation. The FFA has been reported 

to correlate to the auto-ignition temperature and smoke point. In addition to the presentation of the fire 

test data, the measured FFA content of the tested oils are reported. 

5.4.2. Total Heating Time to Ignition 

The time to ignition is the total amount of time from powering the element until flaming ignition occurred. 

Flaming ignition times were recorded through visual observation. This measure of performance 

provides an indication of how much thermal energy was required to initiate a flaming fire for the 

pan/element/oil tested. 

5.4.3. Pan Temperature Thresholds 

In order to assess the potential challenge an ignition test poses to a pan temperature measuring 

device, the time windows between fixed pan temperature thresholds and ignition have been compared. 

For a sensor designed to activate at a fixed temperature threshold, the amount of time available to 

respond prior to ignition is of key significance. When the average pan temperature reached 300°C 

(572°F), the remaining time to ignition and the average oil temperature has been determined and 

reported for each test scenario. In addition, the average pan and oil temperatures have been calculated 

at ignition for all spatial locations and ±3 seconds before and after ignition was observed. 

For each test, several other metrics have been calculated at the time the center pan temperatures 

reached pan temperatures of 250, 300, 350, and 375°C (482, 572, 662, 707°F). Depending on the 

operation of a prevention device, these metrics may indicate the potential for challenges to detection. In 

addition, they provide distinct measures for comparison of variable test scenarios. Other metrics 

calculated at the fixed pan temperature thresholds include: 

1. The slope of the line between the pan temperature threshold and the pan temperature at ignition 

(°C/min), 

2. The slope of the line between the oil temperature at the time the pan threshold was reached and 

the oil temperature at ignition (°C/min), 

3. The difference between the oil temperature and the fixed pan temperature at the time the 

threshold is reached (°C), 

4. The integrated area beneath the smoke obscuration curve up to the time the pan reaches the 

pan temperature thresholds (%/m - min). 

The pan temperature metrics calculated are explained graphically in Figure 10 for a pan threshold of 

375°C (707°F). Comparable values have been calculated for the other pan temperature thresholds. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 19 

Figure 10 – Graphical representation of metrics calculated at pan temperature thresholds 

5.4.4. Smoke Measurement 

This measure of performance indicates the additional heating time between a low level smoke 

measurement in the hood and ignition. Visual observations of smoke production were found to be 

extremely variable, and it was determined through observation of data that smoke measurements 

exceeded the noise and continued to rise until ignition when an average obscuration of 1.6 %/ft (5 %/m) 

was measured between both lasers. When this condition had been met, the total remaining time until 

ignition has been reported. 

This time represents a quantitative evaluation of the time window until ignition after a relatively low level 

of smoke is produced. The metric removes the subjectivity and uncertainty that occurs from evaluating 

first smoke (i.e., related to smoke point) based on a visual assessment of smoke noticeable to an 

observer. In addition to the remaining time, the average pan and oil temperatures at the time of this 

smoke measurement are reported. The averaged values reported include all spatial locations as well as 

data 3 seconds prior to and 3 seconds after each noted time. 

During nearly all tests conducted, the measured smoke obscuration in the collection hood saturated the 

capabilities of the laser measurement system. For this reason, the integral of the smoke obscuration 

curve when fixed pan temperature thresholds have been reached have been calculated. 

HUGHES ASSOCIATES 
     

   

   

   

   

   

   

   

STANDARD COOKING FIRES 1DTG02049.009 PAGE 20 

5.4.5. Gas Measurements 

Gas measurements in the collection hood, including the O2, CO, and CO2, produced little to no 

responses prior to ignition for the tests conducted. Detection devices utilizing these parameters would 

likely provide no response prior to ignition. No additional gas concentration metrics have been 

considered for this analysis. 

5.4.6. Correlation 

The measure of correlation between the tested variables and the performance metrics have been 

calculated using the Pearson’s correlation coefficient, rxy. The correlation coefficient is calculated 

between two data sets by taking the means of the variable and data, and summing products of the 

differences between the data and the mean. This calculation is shown in Equation 1. 

∑೙

೔సభሺ௫೔ି௫̅ሻሺ௬೔ି௬തሻ ݎ௫௬ ൌ Eq. (1) ට∑೙

೔సభሺ௫೔ି௫̅ሻమ ∑೙೔సభሺ௬೔ି௬തሻమ

The Pearson’s correlation provides an estimate of the relationship between the tested variable, xi, and 

the resulting measurement, yi. The value of rxy can range from -1 to 1, with values indicative of the 

relationships shown in Figure 11. These ranges are only relative and interpretative, and do not reflect 

defined rules for the Pearson’s correlation. 

Interpretation of Pearson's Correlation

rxy

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0
 

‐0.1
 

‐0.2
 

‐0.3
 

‐0.4
 

‐0.5
 

‐0.6
 

‐0.7
 

‐0.8
 

‐0.9
 

‐1

Very Strong Positive Relationship

Strong Positive Relationship

Moderate Positive Relationship

Weak Positive Relationship

No or Negligible Relationship

Weak Negative Relationship

Moderate Negative Relationship

Strong Negative Relationship

Very Strong Negative Relationship

Figure 11 – Interpretation of Pearson’s Correlation calculated for test data and variables 

HUGHES ASSOCIATES 
 

 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 21 

In addition to the correlation coefficient, the slope of the response curve is also calculated to provide an 

estimate of the magnitude of the influence of the variable. A correlation of 1.00 is less meaningful when 

the temperature change is only 1 degree in magnitude. 

The correlation between test variables and test measurements has been calculated to identify potential 

relationships. Evaluated variables include: 

 The FFA of the tested oil (%); 

 The power input of the element to the pan (W); 

 The total mass of the test pan (g); 

 The estimated specific heat capacity of the pan; 

o Aluminum = 0.91 J/g-°C 

o Stainless Steel = 0.51 J/g-°C 

o Cast Iron = 0.46 J/g-°C 

 The estimated thermal conductivity of the pan (W/m - °C); 

o Aluminum = 215 W/m - °C 

o Stainless Steel = 54 W/m - °C 

o Cast Iron = 80 W/m - °C 

 The minimum possible heating time to ignition (sec); 

o Calculated as a combination of pan, oil and element variables as shown in Eq. (2) 

ݐ ௡௜௠ൌ ெ೛ೌ೙௖೛ೌ೙்೛ೌ೙,೔೒೙ାఘ೚೔೗௏೚೔೗௖೚೔೗்೚೔೗,೔೒೙ Eq. (2) ொሶ

೐೗೐೘೐೙೟

o Where: 

 Mpan = Pan mass 

 cpan = specific heat capacity of the pan 

 Tpan,ign = the pan temperature at ignition 

 poil = density of the oil (~0.85 g/cm3) 

 Voil = volume of oil, coil = specific heat capacity of oil (1.91 J/g-K) 

 Toil,ign, = the temperature of the oil at ignition 

 Qelement = the thermal output of the element 

 The radius of curvature of the pan base; 

 The angle of tilt of the pan settled on the element surface; and, 

 The diameter of the pan base on the element (cm). 

The relationship between these variables and test measurements have been calculated. The test 

measurements evaluated for correlation include the performance metrics discussed in the preceding 

sections. 

5.4.7. Instrumentation Comparison 

The instrumentation used was also compared to determine the best potential configuration for use in 

standardized testing. For each test, the average pan temperatures were calculated from the 3 spatial 

locations. The difference between each location and the average pan temperature was then calculated 

and averaged across the duration of the test. 

The average oil temperatures were calculated from the 9 spatial locations. The oil temperatures were 

measured in three spatial locations, each at three depths. The difference between the three 

temperatures measured at the half-depth of the oil and the average were calculated and averaged 

across the duration of the test. The difference between the three temperatures taken slightly above the 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009	 PAGE 22 

half-depth and the average oil temperature was also calculated and averaged. This was also repeated 

for the three temperatures taken slightly below the half oil depth. 

Differences between the average result and the two smoke lasers and the four effluent temperature 

measurements were also compared for each test conducted. This data provided a measure of 

uniformity of smoke and heat in the collection hood. The full set of instrumentation comparisons 

calculated for each test includes: 

	 The average difference between the pan temperatures by location (°C) 

	 The average difference between the oil temperatures by location (°C) 

	 The average difference between the oil temperatures by depth (°C) 

	 The average difference between the effluent temperatures by location (°C) 

	 The average difference between the smoke obscuration by location (%/m) 

The comparisons of instrumentation were used for identification of the locations providing 

measurements closest to the average values. This will allow for inclusion of the minimum amount of 

total instrumentation in a test standard while still providing sufficient data for evaluation. 

6. TEST DATA 

6.1. Phase 1 and Phase 2 Test Conditions 

There are three key differences between the Phase 1 and the Phase 2 test series. First, the large, 

exposed bead thermocouples used in the Phase 1 testing were replaced with smaller, Inconel sheathed 

thermocouples in Phase 2. These thermocouples had a faster response time, were easier to place at 

accurate depths, and were easier to clean between tests. Second, at the advice of the range industry, 

the base pan size was increased from 8 in. (20 cm) to 10 in (25 cm). This change increased the amount 

of oil needed to achieve a 1⁄4 in. (6.4 mm) oil depth from 13.4 in.3 (220 mL) to 18.3 in.3 (300 mL). The 10 in. 

(25 cm) size pan was considered more appropriate for use on the large cooktop element. Third, the test 

apparatus was moved from an enclosed room to an operating exhaust hood. The test data have been 

compared to determine the impacts from these changes to the test conditions. Detailed analysis of 

these observations are provided in the following sections. 

The primary observations include: 

1. Oil temperatures measured from the start to ignition in Phase 1 were lower than those 

measured in Phase 2 by 18°C (32°F) on average. This effect is likely due to the greater thermal 

lag of the Phase 1 thermocouples. The difference between the oil temperatures measured in 

Phase 1 and Phase 2 tests was greatest when the oil temperatures were changing most rapidly 

and less difference was observed for slower heating rates. 

2. Larger pans and greater oil volumes used for baseline testing in Phase 2 generally resulted in 

longer total heating times to reach ignition when all other variables remained the same 

(aluminum pans, 2600 W element). 

3. Local airflow conditions does not appear to have affected the test measurements in any 

significant way. The ventilation hood removed the spillover but did not prevent effluent from 

rising naturally and collecting into the measurement hood. 

The differences in measured oil temperatures (Phase 1 v. Phase 2) affected the usage of the data in 

the analysis. The difference in measured temperatures is considered systematic, and the Phase 1 data 

was still applicable to identify how a change in pan size or oil type affected the measurements. Data 

from both Phase 1 and Phase 2 oil TCs were used to establish the effect of variables and identify 

trends. Because the magnitude of the measured temperatures was different, however, the Phase 1 oil 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 23 

temperature data was excluded from any analysis conducted to establish the maximum allowable oil 

temperatures for a potential standard test. 

6.1.1. Oil Temperature Measurement 

The oil temperatures measured during the Phase 1 tests were \an average of 54°C (97°F) lower than 

the pan temperatures when measured from the start of heating until ignition occurred. The oil 

temperatures measured during the Phase 2 tests were an average of 36°C (65°F) lower than the pan 

temperatures. In general, the pan temperatures measured during both Phases were comparable, and 

so the Phase 1 tests measured an average oil temperature approximately 18°C (32°F) lower than in 

Phase 2 tests from the start of heating until ignition. For the same measured pan temperature, the 

measured oil temperature was lower in Phase 1 than Phase 2. 

The difference between the oil temperatures measured in the Phase 1 and Phase 2 tests was the 

greatest when the temperatures were increasing most rapidly. The difference can therefore be 

attributed to the increased thermal inertia of the Phase 1 thermocouples. When considering only the 

last 60 seconds of each test, when the temperatures were observed to change less rapidly, the Phase 1 

tests report an average pan/oil temperature difference of 35°C (63°F) and 20°C (36°F) for the Phase 2 

tests. 

A number of test variables were changed across the scope of the Phase 1 and Phase 2 tests including 

pan sizes, range types and power, pan materials, and oil types. These variables may also impact the 

measured pan and oil temperatures. When comparing only the most similar test conditions between the 

phases, the difference in measured oil temperatures remained consistent with the overall average 

values reported above. Figure 12 shows a comparison of Phase 1 and Phase 2 tests conducted with 

Crisco brand canola oil on the 2600 W electric coil element with 8 gauge aluminum pans (Tests P1-11 

and P2-5a). 

Figure 12 – Comparison of pan and oil temperature measurements in Phase 1 and Phase 2 tests 

The only differences between the tests were the size of the pan (8 in. (20 cm) for Phase 1, 10 in. (25 cm) for 

Phase 2) and the volume of oil heated (same depth). It can be seen that the pan temperatures 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 24 

measured in the two tests are much closer than the oil temperatures. The difference between the pan 

and oil temperatures measured in test P1-11 were found to be 47°C (85°F) averaged over the entire 

test and 25°C (45°F) during the final 60 seconds before ignition. The average difference between the 

pan and oil temperatures measured in test P2-5a was 33°C (59°F) during the entire test and 20°C (36°F) 

during the final 60 seconds before ignition. These values are in line with the average across all tests in 

Phase 1 and Phase 2 discussed above. 

The temperatures of the oil measured at the time of ignition between Phase 1 and Phase 2 tests are 

closer than the test average, differing by an average of 15°C (27°F). The slope of the temperature 

change was generally lowest at the point of ignition, and the slope was inversely proportional to the 

total heating time. Therefore, for tests reaching the ignition point rapidly, the oil temperatures measured 

during Phase 1 tests will be lower than for Phase 2 testing. The differences between the Phase 1 and 

Phase 2 oil temperatures at ignition were reduced for tests requiring longer heating times to reach 

ignition. The oil temperature measurements obtained during Phase 2 are considered more accurate. 

Where data is used for comparison of test scenarios and selection of potential tests, the Phase 2 oil 

data has been given precedence. 

The data analysis was conducted in several discrete portions. When considering the impact of 

variables on the ignition times, temperatures, or smoke production, both the Phase 1 and Phase 2 data 

were included in the analysis. Although the oil temperatures measured in each Phase differ, the 

general trends resulting from changing test variables remain valid. The Phase 1 and Phase 2 data 

have been presented and considered for each variable discussed in this report. In Sections 7, 8, and 9, 

however, the magnitude of the oil temperatures is of key significance for determining the global trends, 

comparing the instrument locations, and recommending thresholds for a standardized test. Only the 

Phase 2 data was considered for these analyses. 

6.1.2. Pan Size 

At the recommendation of appliance industry representatives on the project technical panel, the 

baseline pan size was increased from 8 in. (20 cm) in Phase 1 to 10 in. (25 cm) in Phase 2. It was 

suggested that this was a more realistic application for the large range element. Increasing the pan size 

required an increase in the oil volume required to maintain a 1⁄4 in. (6.4 mm) initial oil depth. In general, 

increasing the pan size and oil volume resulted in longer total heating times to reach ignition. 

Direct comparisons were made between tests conducted in Phase 1 with fresh oils in 8 in. (20 cm), 8 gauge 

aluminum pans on the 2600 W electric coil (Tests P1-1 through P1-13) and the tests conducted in 

Phase 2 with fresh oils in 10 in. (25 cm), 8 gauge aluminum pans on the 2600 W electric coil (Tests P2-1 

through P2-9). The average total heating time to reach ignition increased from 526 seconds in Phase 1 to 

651 seconds in Phase 2. An increase in oil volume of 36% (220 mL to 300 mL) and an increase in pan 

diameter of 25% resulted in an average increase in ignition time of 23%. 

6.1.3. Local Airflow Conditions 

Phase 1 tests were conducted with the apparatus in an enclosed room with no airflow. The effluent 

from the pan rose naturally from buoyancy into the collection hood. The spillover was allowed to collect 

in a large room with a small operating exhaust duct in one corner of the ceiling. Phase 2 tests were 

conducted with the apparatus placed beneath an operating exhaust hood. When effluent spilled from 

the collection hood, it was immediately removed by the larger hood exhaust. This reduced the total 

turnaround time between tests conducted. 

No horizontal air flows were observed across the range top, and the effluent rose vertically from 

buoyancy and collected in the hood. The operating exhaust hood was not found to visually impact the 

rising effluent. Measurements of the smoke obscuration in the hood confirm that comparable amounts 

of smoke were collected between similar test conditions. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 25 

6.2. Free Fatty Acid Content 

All evaluated oils were tested for the FFA content. Details of the oils are discussed in Section 5.2.3. 

Several of the oil samples from Phase 1 tests were subjected to sustained heating in an attempt to 

simulate use and artificially increase the FFA through “aging.” One other sample of oil was obtained 

after lunch time from the deep fryer of a fast food restaurant. The vegetable oil and pork lard used in 

Phase 2 were subjected to repeated chicken frying to produce “used” oil. The various oils subjected to 

fire testing and the measured FFA of each are shown in Table 3. 

Table 3 – Free fatty acid content of tested oils 

PHASE 1 TESTING 

Oil Type New Oil FFA (%) Artificially Aged 8 hour FFA (%) 

Soybean Oil (Commercial) 0.044 0.14 

Wesson Vegetable Oil (Soybean) 0.024 

Crisco Vegetable Oil 0.023 

Used Fast Food Vegetable Oil 

(Soybean) 4.4a 

Canola Oil (Commercial) 0.021 0.12 

Wesson Canola Oil 0.023 

Crisco Canola Oil 0.020 

Corn Oil (Commercial) 0.064 0.16 

Peanut Oil (Commercial) 0.021 0.035 

Beef Shortening (Commercial) 0.023 0.07 

Pork Lard (Commercial) 0.21 0.26 

PHASE 2 TESTING 

Oil Type New Oil FFA (%) 

Used Oil (fry chicken) FFA 

(%) 

Great Value Vegetable Oil 0.035 0.56 

Morrell Pork Lard 0.23 0.56 

Great Value Canola Oil 0.02 

Crisco Canola Oil 0.02 

Wesson Canola Oil 0.023 

Generic Brand Canola Oil 0.035 

a – Oil used in deep fryer not artificially aged 8 hours 

The simulated aging process of Phase 1 was observed to increase the FFA of the oils for all tested 

cases. The minimum resulting increase was observed for peanut oil, with an increase of 0.014% FFA, 

and the maximum increase in FFA was observed for both the soybean and corn oils, increasing by 

0.096% FFA. However, the increase in the FFA due to sustained heating was less than observed for 

the oil used in a fast-food restaurant deep fryer for cooking, which reported 4.4% FFA, an increase over 

the commercial soybean oil of two orders of magnitude. Although no sample of the fresh fast food oil 

was obtained or tested, it was known that the oil was soybean oil. Based on other experiments 

comparing brands, it is expected to be comparable to both the commercial and consumer soybean oils 

tested, which did not show much difference based on source as discussed in section 6.5. 

Oil usage through chicken frying conducted in Phase 2 increased the oil % FFA from 0.035 for the 

vegetable oil to 0.56% FFA and from 0.23 to 0.56% FFA for the pork lard. These values are significantly 

lower than the 4.4% FFA measured for the fast food oil obtained in Phase 1, possibly because of the 

straining of solid particulate or the consistent recipe and procedures used. These oils were used for real 

cooking of fatty meats with breading and were used to the point most people would likely dispose of 

them. They are representative of re-used oils in real kitchens. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 26 

Each of the oils were subjected to a baseline test, which included the use of an 8 gauge aluminum pan 

placed on the 2600 W, 8 in. (20 cm) element of the GE range on its highest setting. All tests used 1⁄4 in. 

(6.4 mm) oil depth. Phase 1 tests used an 8 in. (20 cm) pan and Phase 2 tests used a 10 in. (25 cm) 

pan. The pan and oil temperatures when measureable smoke was observed and at ignition for these 

tests are shown in Figure 9 as a function of the FFA. The previously reported impact of FFA on heated 

oil smoke production and ignition are also shown in Figure 13 [3]. The reported data was obtained for 

observations of smoke and ignition of a droplet of oil placed onto a fixed temperature hotplate. The 

temperatures obtained for new test data are for the bulk oil temperatures when the smoke meters 

measured 1.6%/ft (5%/m) smoke obscuration or when the oil ignited, and are greater than the 

measured droplet temperatures from the previous data. 

Figure 13 – Average oil temperatures at smoke measurement and ignition as a function of the 

% FFA content of the tested oil (lines are from Ref 3) 

Although there is a significant amount of variability in the data, two distinct trends can be observed. The 

temperature of the oil when smoke is measured in the collection hood decreases with increasing 

% FFA. Although the magnitude of the temperatures are higher, the general trend of the smoke 

temperatures follows the trend of the reference data for smoke point. 

The second trend is the temperature of the oil at ignition is relatively unaffected by the % FFA for the 

oils evaluated. The solid red point well above the rest of the data was obtained from the deep fryer oil 

test, with a % FFA of 4.4. The ignition temperature remained within the bounds of the fresh and aged oil 

tests conducted. In phase 2 testing, the % FFA increased as oil was used, and the average ignition 

temperatures increased as well, rather than decrease as predicted by the reference data. While the 

ignition temperatures may drop off drastically at much higher % FFA, it appears that for used cooking 

oils, even those used repeatedly, the % FFA does not increase enough to significantly impact the 

ignition temperatures. 

6.3. Oil Type 

Fire tests were conducted on numerous types of oils. Phase 1 tests were conducted using commercial 

grade oils, including soybean (vegetable), corn, canola, peanut, beef shortening, and pork lard. These 

commercial grade oils were obtained from an industrial supplier. In addition, Wesson and Crisco 

consumer brand soybean (vegetable) and canola oils were tested. Phase 2 tests were conducted using 

consumer brand soybean (vegetable) and canola oils, and pork lard. Detailed analysis comparing oil 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 27 

types is provided in the following section. The primary observations from comparisons of the oil data 

include: 

 Oils with higher % FFA generally had 

o Longer heating times to reach ignition 

o Longer time windows between a fixed pan temperature measurement and ignition 

o Longer time windows between smoke production and ignition 

o Lower temperatures at the production of smoke 

o Unaffected temperatures at ignition 

 Based on these results, canola oil was selected for continued testing due to: 

o Fastest heating to ignition 

o Shortest time window for both pan temperature and smoke activation devices 

All Phase 1 oil evaluation tests were conducted on the 8 in. (20 cm) element of the 2600 W GE range, 

in an 8 in. (20 cm) diameter, 8 gauge aluminum frying pan. A total of 13.4 in.3 (220 mL) of oil was used 

for each test, resulting in an initial oil depth of 1⁄4 in. (6.4 mm). All Phase 2 oil evaluation tests were 

conducted on the 8 in. (20 cm) element of the 2600 W GE range, in a 10 in. (25 cm) diameter, 8 gauge 

aluminum frying pan. A total of 18.3 in.3 (300 mL) of oil was used for each test, resulting in an initial oil 

depth of 1⁄4 in. (6.4 mm). The tests included in the oil type analysis are listed in Table 4. 

Table 4 – Tests included in oil type analysis 

Identifier Oil Type Test ID 

Phase 1 

Canola 

Crisco Canola P1-11 

Wesson Canola P1-13 

Commercial Canola P1-5 

Commercial Canola P1-6 

Peanut Commercial Peanut Oil P1-7 

Shortening Commercial Beef Shortening P1-8 

Soybean (Vegetable) 

Crisco Vegetable Oil P1-10 

Wesson Vegetable Oil P1-12 

Commercial Soybean oil P1-1 

Corn 

Commercial Corn Oil P1-2 

Commercial Corn Oil P1-3 

Commercial Corn Oil P1-4 

Pork Lard Commercial Pork Lard P1-9 

Phase 2 

Canola 

Great Value Canola Oil P2-4 

Great Value Canola Oil P2-5 

Great Value Canola Oil P2-6 

Great Value Canola Oil P2-4a 

Crisco Canola Oil P2-5a 

Generic Brand Canola Oil P2-6a 

Soybean (Vegetable) 

Great Value Vegetable Oil P2-1 

Great Value Vegetable Oil P2-2 

Great Value Vegetable Oil P2-3 

Pork Lard 

Morrell Pork Lard P2-7 

Morrell Pork Lard P2-8 

Morrell Pork Lard P2-9 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 28 

6.3.1. Available Response Times 

A key metric for comparison of the tests is the total amount of time required to reach ignition. The total 

heating times required to reach ignition are shown in Figure 14, with the oils approximately ordered 

from lowest to highest percent FFA. The blue bars show the full range of heating times from all included 

tests. The red line reports the mean time among each test type, with the dashed red lines showing ±1 

standard deviation from this mean. The green line and shaded region and orange line and shaded 

region show the mean ±1 standard deviation for the Phase 1 and Phase 2 tests, respectively. 

Figure 14 – Heating times until ignition for various oil types (Phase 2 times for larger pan with 

more oil volume than Phase 1) 

The average heating time to ignition was increased from 526 seconds for the 8 in (20 cm) pans used in 

Phase 1 to 651 seconds for the 10 in (25 cm) pans with 300 mL of oil used in Phase 2. Heating times 

falling outside of a standard deviation from the averages of all tests in a test phase include one fast 

canola oil and a peanut oil test in Phase 1, one fast canola oil test in Phase 2, one slow corn and 

soybean oil test in Phase 1, and two slow pork lard tests in Phase 2. 

The oil % FFA were correlated to the average total heating times for each of the test scenarios shown 

in Table 4. For test scenarios using several brands of oils with different % FFA (i.e., canola oils in 

Phase 2), an average % FFA was used for calculation. The calculation of these metrics is shown in 

Figure 15. However, a strong positive correlation was not measured for the Phase 1 tests. Rather, a 

weak negative correlation of -0.20 was calculated. This value was mostly caused by the high FFA of the 

pork and the fast heating time to ignition observed for the single test conducted. When the pork lard is 

removed from consideration, a correlation between FFA and total heating time to ignition of 0.67 is 

calculated for the Phase 1 data with a slope of 1307 sec per % FFA. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 29 

Figure 15 – Calculated correlations and slopes for heating time to ignition and % FFA 

The potential challenge for a detection device measuring pan temperatures is related to the amount of 

time available between a specific pan temperature and ignition. For this analysis, an arbitrary fixed pan 

temperature of 300°C (572°F) has been chosen for evaluation. Other values in the range of 250–375°C 

(482–707°F) could also have been chosen, and the respective time windows would vary accordingly. 

The time windows between an average pan temperature of 300°C (572°F) and ignition for the Phase 1 

and Phase 2 oil type tests are shown in Figure 16. 

Figure 16 – Time window between pan temperature = 300°C (572°F) and ignition for various oil 

types 

The potential time window for pan temperature activation devices scales nearly proportionally to the 

total heating times. Average time windows for 300°C (572°C) pan activation of 227 seconds and 311 

seconds were measured for Phase 1 and Phase 2 tests, respectively. The correlations between the pan 

temperature windows and ignition times were 0.88 (0.50 sec window per sec heating time) and 0.99 

(0.68 sec window per sec heating time) for the Phase 1 and Phase 2 tests, respectively. The tests with 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 30 

the shortest time windows for both tests series included the use of canola oil, which also had the lowest 

measured % FFA. 

The potential challenge for a detection device measuring smoke is directly related to the amount of time 

between the initial production of smoke and ignition. For this analysis, the time of smoke production 

was defined as the time an average smoke obscuration of 1.6%/ft (5%/m) was measured by the lasers. 

The time window between this smoke measurement and ignition are shown for the various oil types in 

Figure 17. 

Figure 17 – Time window between smoke obscuration = 1.6%/ft (5%/m) and ignition for various 

oil types 

The potential time window for smoke activation devices scales nearly proportionally to the total heating 

times and pan temperature windows. Average time windows for low smoke measurement of 162 

seconds and 240 seconds were measured for Phase 1 and Phase 2 tests, respectively. This is 

approximately 1 minute shorter than the available time window for 300°C (572°F) pan temperature 

activation. It should also be considered that the smoke concentrations measured for this test apparatus 

are higher than those expected in larger kitchens, especially those with operating exhaust hoods. The 

available time window was observed to increase with increasing % FFA, with correlation factors of 0.63 

(slope = 205 sec per % FFA) and 0.93 (slope = 322 sec per % FFA) for Phase 1 and Phase 2, 

respectively. These calculations are shown in Figure 18. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 31 

Figure 18 – Calculated correlations and slopes for time window between smoke and ignition and 

% FFA 

6.3.2. Temporal Heating Curves 

Temporal plots of the average pan and oil temperatures, and average smoke obscuration for all oils 

tested (Table 3) are shown in Figure 19. The tests have all been aligned by the time of ignition (T = 0). 

The solid lines show the average among the Phase 1 and Phase 2 tests included in the analysis, and 

the dashed lines show the maximum and minimum values measured at the given time before ignition 

occurred. 

The total heating time and available activation windows are clearly shorter for the Phase 1 Tests using 

an 8 in. (20 cm) pan compared to the Phase 2 tests using a 10 in. (25 cm) pan. The smoke obscuration 

begins increasing rapidly after the pan and oils reach approximate temperatures of 340°C (644°F) and 

280°C (536°F), respectively. Although the Phase 2 tests take longer to reach ignition, the pan and 

smoke temperatures generally converge at the ignition time with the faster Phase 1 tests. The oil 

temperature measurements, however, remain higher as a result of the more responsive thermocouples. 

A number of metrics have been calculated to compare the temporal response curves of the various oil 

types. These metrics include the slopes of the temperature and obscuration curves to ignition at various 

fixed points, the difference between the pan and oil temperatures at the time of ignition, and the total 

integrated area under the smoke obscuration curve at ignition. These values are shown in Table 5. 

In general, the greater the slope, the greater the challenge the fire source presents to a mitigation 

device since a greater slope indicates a more rapid change from normal to hazardous conditions. For 

the difference between pan and oil temperatures, the smaller the difference, the greater the challenge 

to a fire prevention device that is monitoring pan temperature. A smaller difference would result in 

higher oil temperatures for the same pan temperature measurement, therefore increasing the likelihood 

of ignition. For smoke detection devices, the lower the integrated value, the greater the challenge the 

fire source presents to a system that is monitoring smoke as a criteria for control. The cases presenting 

the greatest challenges to prevention devices are highlighted for each criteria and test phase. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 32 

Figure 19 – Pan and oil temperatures and smoke obscuration curves for oil types tests (Table 3) 

aligned by ignition time 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 5 – Calculated pan and oil temperature slopes and obscuration slope and integrated areas 

Oil 

Average pan temp slope 

between fixed pan 

temperatures and ignition 

(°C/min) 

Average oil temp slope 

between fixed pan 

temperatures and ignition 

(°C/min) 

Difference between pan and oil 

temperature at fixed pan temps 

(°C) 

Inte

250 °C

(482 °F)

300 °C

(572 °F)

350 °C

(662 °F)

375 °C

(707 °F)

250 °C

(482 °F)

300 °C

(572 °F)

350 °C

(662 °F)

375 °C

(707 °F)

250 °C

(482 °F)

300 °C

(572 °F)

350 °C

(662 °F)

375 °C

(707 °F)

IGN

250 °C

(482 °F)

P1 

Canola 35 31 25 20 42 38 33 31 63 58 51 50 32 0 

Peanut 40 35 29 24 51 47 45 42 132 125 120 113 87 ‐8 

Shortening 33 29 24 21 41 36 30 29 80 72 60 60 38 1 

Soybean 33 29 24 20 37 34 32 29 65 65 63 60 41 0 

Corn 33 30 24 21 39 36 34 31 65 66 63 57 40 ‐2 

Pork Lard 38 34 28 23 44 40 40 40 51 45 50 50 25 0 

P2 

Canola 26 22 17 14 29 26 24 24 33 31 35 35 14 0 

Soybean 23 20 15 12 26 24 20 19 43 45 41 41 21 0 

Pork Lard 21 18 14 12 25 23 22 21 40 42 41 38 12 0 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 34 

6.3.3. Smoke Production and Ignition Temperatures 

In addition to the total heating times and potential activation windows, the pan and oil temperatures 

measured at the time smoke is produced and at ignition provide a more direct comparison of the 

properties of the oil types. These metrics are not as affected by test variables such as the total oil 

volume or pan size. The average pan temperatures at the time of low smoke measurements are shown 

in Figure 20. The blue bars show the full range of all pan temperatures measured from each of three 

locations ±3 seconds from the measurement of 1.6%/ft (5%/m) smoke. The red line reports the mean 

time among each test type, with the dashed red lines showing ±1 standard deviation from this mean. 

The green line and shaded region and orange line and shaded region show the mean ±1 standard 

deviation for all the Phase 1 and Phase 2 tests, respectively. 

Figure 20 – Average pan temperature at 1.6%/ft (5%/m) smoke measurement for various oils 

Average pan temperatures at average smoke obscuration of 1.6%/ft (5%/m) ranged from 312°C 

(594°F) for the Phase 1 pork lard to 359°C (678°F) for the Phase 1 peanut oil. The average pan 

temperatures measured when moderate smoke production begins decreased with an increase in 

% FFA. Correlation coefficients between pan temperatures at smoke and % FFA of -0.97 and -0.99 

were calculated for the Phase 1 and Phase 2 tests, respectively. Although distributed evenly in the 

Figure, the pork lard has a % FFA an order of magnitude higher than the other oils, and the reduction in 

pan temperature at smoke production is apparent. Oils with low % FFA, such as canola oil, produce 

smoke at higher temperatures, and therefore likely present a greater challenge for ignition prevention 

devices measuring smoke. If potential nuisance alarms are a consideration, however, oils with higher % 

FFA, such as pork lard provide the greatest potential challenge. The correlations and slopes of the pan 

temperatures at smoke and % FFA for Phase 1 and Phase 2 tests are shown in Figure 21. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 35 

Figure 21 – Calculated correlations and slopes for pan temperatures at 1.6%/ft (5 %/m) smoke 

measurement and % FFA 

The oil temperatures measured at the time of 1.6%/ft (5 %/m) smoke measurement are shown in Figure 22. 

The blue bars show the full range of all oil temperatures measured from each of nine locations ±3 

seconds from the measurement of smoke. The red line reports the mean time among each test type, 

with the dashed red lines showing ±1 standard deviation from this mean. The green line and shaded 

region and orange line and shaded region show the mean ±1 standard deviation for the Phase 1 and 

Phase 2 tests, respectively. 

Figure 22 – Average oil temperature at 1.6%/ft (5%/m) smoke measurement for various oils 

Average oil temperatures at smoke production ranged from 222°C (432°F) for the Phase 1 pork lard to 

294°C (561°F) for the Phase 2 canola oils. It should be noted that the oil temperature measurements 

made in Phase 1 were less responsive and generally lower than those made for Phase 2 (see 

Section 6.1.1), and this can be seen in the data above. The oil temperatures when moderate smoke 

production begins show an extremely strong negative correlation to the % FFA of the oil. Correlation 

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coefficients of -0.99 and -0.99 were calculated for the Phase 1 and Phase 2 tests, respectively. The 

calculation of the correlation coefficients are shown in Figure 23. 

Figure 23 – Calculated correlations and slopes for oil temperatures at smoke measurement and 

% FFA 

Scenarios with the lowest pan and oil temperatures at ignition present the greatest challenge for fire 

prevention systems. The pan and oil temperatures measured at ignition are shown in Figures 24 and 25, 

respectively. 

Figure 24 – Average pan temperatures at ignition for various oils 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 37 

Figure 25 – Average oil temperatures at ignition for various oils 

Average pan temperatures measured at ignition were 414°C (777°F) and 407°C (765°F) for Phase 1 

and Phase 2, respectively. There were a few low temperature outliers in the Phase 1 data as shown by 

the blue bar, representing all measured values. Comparing the average and standard deviations 

shown by the red bars the two Phases are much closer in total variability. The reduced average pan 

temperature at ignition was often observed for tests with longer total heating times, as for the Phase 2 

tests compared to Phase 1. This observation is discussed in greater detail in sections 6.6, 6.7, and 7.0. 

Average oil temperatures at ignition of 373°C (703°F) and 388°C (730°F) were measured for the Phase 

1 and Phase 2 tests, respectively. It should be noted, however, that the thermocouples used in Phase 1 

were less responsive (see discussion in Section 6.1.1) and found to measure lower temperatures in 

general than the Phase 2 test instruments. 

The impact of the oil type (and % FFA) is much less pronounced for the pan and oil temperatures at 

ignition compared to the other evaluated test metrics. The pan and oil temperature correlations and 

calculated slopes as a function of % FFA are shown in Figure 26. The correlations between the pan 

and oil temperatures at ignition and % FFA for the Phase 1 tests were found to be 0.14 and 0.23, 

respectively. The correlations between the pan and oil temperatures and % FFA for the Phase 2 tests 

were much stronger, with values of 0.97 and 0.93, respectively. Although these show an extremely 

strong correlation, when put in context with the magnitude of temperature change, the effects are much 

less notable. The total change in average pan temperature from the canola to the pork lard was 2°C 

(4°F). The total change in average oil temperature from the soybean oil to the pork lard was 11°C 

(20°F). Regardless of the importance of the magnitude, a negative correlation between temperature at 

ignition and % FFA for fresh oils was not observed for these tests, as was predicted by previous oil test 

data [3]. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 38 

Figure 26 – Calculated correlations and slopes for pan and oil temperatures at ignition and 

% FFA 

6.4. Aged/Used Oil 

Commercial oil samples used in Phase 1 testing were artificially “aged” by continuous heating at 204°C 

(400°F) for 8 hours. In addition, a sample of used soybean (vegetable) oil was obtained from a fast food 

restaurant deep fryer in order to evaluate a used oil. Consumer oil samples used in Phase 2 testing 

were “used” by repeatedly cooking breaded chicken thighs until the oil was deemed unusable. The 

primary observations from these tests include: 

	 Aged oils had: 

o	 Higher % FFA 

o	 Little change in total heating time to ignition or the available time between pan 

temperature or smoke production thresholds, with slight reductions from fresh to aged oil 

within the fresh oil test standard deviation 

o	 Little to no change in the pan and oil temperatures at the production of smoke or at 

ignition, with variations within test standard deviations 

	 Used oils had: 

o	 Higher % FFA 

o	 Increased total heating time to ignition and available time between pan temperature and 

smoke production thresholds 

o	 Little to no change in the pan and oil temperatures measured at ignition 

o	 Reduced pan and oil temperatures at the time smoke production began 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 39 

	 Based on the results of these tests, the use of fresh canola oil is recommended to provide the 

greatest overall challenge for fire prevention systems based on pan temperature or smoke 

detection devices. Fresh canola oil had the: 

o	 Shortest heating time to ignition, and shortest time window for pan/smoke activation 

o	 Highest temperatures at smoke production 

o	 Same approximate ignition temperatures as other oils tested 

All aged/used oil evaluation tests were conducted on the 8 in. (20 cm) coil element of the 2600 W GE 

range, in an 8 gauge aluminum frying pan. A total of 13.4 in.3 (220 mL) of oil was used in 8 in. (20 cm) 

pans for the Phase 1 tests, and 18.3 in.3 (300 mL) in 10 in (25 cm) pans for each Phase 2 test. Both 

phases evaluated an initial oil depth of 1⁄4 in. (6.4 mm). The tests included in the aged/used oil analysis 

are listed in Table 6. 

Table 6 – Tests included in aged/used oil analysis 

Identifier Oil Type Test ID 

Phase 1 

Canola 

Crisco Canola Oil P1-11 

Wesson Canola Oil P1-13 

Commercial Canola Oil P1-5 

Commercial Canola Oil P1-6 

Aged Canola “Aged” Commercial Canola Oil P1-16 

Peanut Commercial Peanut Oil P1-7 

Aged Peanut “Aged” Commercial Peanut Oil P1-17 

Soybean (Vegetable) 

Crisco Vegetable Oil P1-10 

Wesson Vegetable Oil P1-12 

Commercial Soybean oil P1-1 

Aged Soybean “Aged” Commercial Soybean Oil P1-14 

Used Soybean Vegetable oil removed from fast food deep fryer P1-19 

Corn 

Commercial Corn Oil P1-2 

Commercial Corn Oil P1-3 

Commercial Corn Oil P1-4 

Aged Corn “Aged” Commercial Corn Oil P1-15 

Pork Lard Commercial Pork Lard P1-9 

Aged Lard “Aged” Commercial Pork Lard P1-18 

Phase 2 

Soybean (Vegetable) 

Great Value Vegetable Oil P2-1 

Great Value Vegetable Oil P2-2 

Great Value Vegetable Oil P2-3 

Used Soybean 

“Used” Great Value Vegetable Oil P2-10 

“Used” Great Value Vegetable Oil P2-11 

“Used” Great Value Vegetable Oil P2-12 

Pork Lard 

Morrell Pork Lard P2-7 

Morrell Pork Lard P2-8 

Morrell Pork Lard P2-9 

Used Lard 

“Used” Morrell Pork Lard P2-13 

“Used” Morrell Pork Lard P2-14 

“Used” Morrell Pork Lard P2-15 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 40 

6.4.1. Available Response Times 

The total heating times required to reach ignition are shown in Figure 27, with the oils approximately 

ordered from lowest to highest percent FFA for the fresh oils. The blue bars show the full range of 

heating times from all included tests. The red line reports the mean time among each test type, with the 

dashed red lines showing ±1 standard deviation from this mean. The green line and shaded region and 

orange line and shaded region show the mean ±1 standard deviation for the fresh oil and the 

aged/used oil tests, respectively. 

Figure 27 – Heating times until ignition for aged/used oils 

The total heating time to ignition remained relatively unchanged for the aged oils tested in Phase 1, with 

the average time reduced from 526 to 498 seconds. The total heating time was increased for the used 

oils tested in Phase 2 from 688 to 736 seconds, an increase of approximately one standard deviation 

compared to the fresh oils. The correlation and slope of the heating time to ignition and % FFA are 

shown in Figure 28. The longer heating times required for Phase 2 are a result of the larger pans and 

oil volumes compared to Phase 1, and not due to the conditioning of the oils. 

The potential time windows for activation of pan temperature and smoke detection devices have also 

been considered. The average, standard deviation, and full range of time for pan and smoke activation 

are shown in Figures 29 and 30, respectively. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 41 

Figure 28 – Calculated correlations and slopes for total heating times to ignition and % FFA for 

used/aged oils 

Figure 29 – Time window between pan temperature = 300°C (572°F) and ignition for aged/used 

oils 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 42 

Figure 30 – Time window between smoke obscuration = 1.6%/ft (5%/m) and ignition for various 

oil types 

The available time windows for pan temperature activation were relatively unaffected by the aging 

process used in Phase 1 testing. The average time window for pan temperature activation was reduced 

from 227 to 205 seconds for fresh and used oils, respectively, as shown by the brown and green lines 

in Figure 29. No clear trend in time reduction was observed when comparing each fresh oil to its aged 

counterpart for the Phase 1 tests. Both pan and smoke time windows were increased for the used oils 

tested in Phase 2, however. 

The available time windows for smoke were increased more than the windows for pan temperature 

activation. This would result in less challenging detection/prevention scenarios for aged/used oils. The 

correlations and slopes for the smoke time and % FFA are shown in Figure 31. Correlation coefficients 

between the smoke windows and the % FFA were 0.81 and 0.89 for the Phase 1 and Phase 2 test, 

respectively. The increase in the duration of the smoke window was much greater for the Phase 2 tests, 

with an average increase in available time of 216 seconds per % FFA compared to 23 for Phase 1. 

Figure 31 – Calculated correlations and slopes for smoke activation window and % FFA for 

used/aged oils 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 43 

6.4.2. Temporal Heating Curves 

Temporal plots of the average pan and oil temperatures, and average smoke obscuration for the 

aged/used oil tests are shown in Figure 32. The tests have all been aligned at the time of ignition 

(T = 0). The solid lines show the average among the Phase 1 and Phase 2 tests, and the dashed lines 

show the maximum and minimum values measured at the given time before ignition occurred. 

Figure 32– Pan and oil temperatures and smoke obscuration curves for aged/used oil tests 

aligned by ignition time 

The average pan and oil temperature curves for the Phase 1 fresh and aged/used oils track nearly 

identically. There was greater variability in the Phase 1 fresh oil tests, and the aged/used oil pan and oil 

temperature bounds fit entirely within the range of fresh oil tests. A slightly greater amount of smoke 

was produced earlier in the aged/used oil tests of Phase 1, with greater variability than the fresh oils. 

With regard to temperature measurement, little to no difference would be seen between the fresh and 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 44 

aged/used oils tested. With regard to smoke measurement, the aged/used oils would be slightly easier 

to detect prior to ignition. 

The used oils tested in Phase 2 heated more slowly than the fresh oils, with higher temperatures 

measured longer before ignition. In addition, more smoke was produced longer before ignition for the 

used oils. Using either pan or smoke detection devices, ignition prevention would likely be easier for the 

used oils tested. 

A number of metrics have been calculated to compare the temporal response curves of the fresh and 

aged/used oils. These metrics include the slopes of the temperature and obscuration curves to ignition 

at various fixed points, the difference between the pan and oil temperatures at the time of ignition, and 

the total integrated area under the smoke obscuration curve at ignition. These values are shown in 

Table 7. The most challenging test conditions for each metric have been highlighted for each test 

phase. 

6.4.3. Smoke Production and Ignition Temperatures 

The pan and oil temperatures measured at the time smoke was produced and at ignition provide a 

direct comparison of the fresh and aged/used oils. These metrics reduce the importance of variables 

such as the total oil volume or pan size. The average pan temperatures at the time of low smoke 

measurements are shown in Figure 33. The blue bars show the full range of all pan temperatures 

measured from each of three locations ±3 seconds from the measurement of smoke. The red line 

reports the mean time among each test type, with the dashed red lines showing ±1 standard deviation 

from this mean. The green line and shaded region show the mean ±1 standard deviation for the fresh 

oil tests conducted in each Phase. The orange lines show the mean ±1 standard deviation for the 

aged/used oil tests conducted in each test phase. 

The pan temperatures at smoke production were generally unaffected by the artificial aging process 

used for Phase 1 testing. The pan temperature at smoke production for the used oil removed from the 

fast food fryer was significantly reduced from the fresh oil average of 345°C (653°F) to 254°C (489°F). 

This indicates that the artificial aging process may not accurately replicate oil usage. However, the 

large difference may also be associated with commercial cooking use compared to home cooking use 

as seen with the Phase 2 used oils. 

The pan temperatures at smoke production for the Phase 2 testing were noticeably reduced by the oil 

usage. The oils tested in this Phase were used to deep fry chicken, and the average pan temperature 

at smoke production was reduced by 30°C (54°F) for the soybean and pork lards tested. The effect was 

not as drastic as observed for the deep fryer oil tested in Phase 1, and this could be due to the fine 

mesh filter used to remove particulate for the Phase 2 oils. The % FFA for the used oils was increased 

to 0.56, and this was also an order of magnitude below the % FFA of 4.4 measured for the deep fryer 

oil in Phase 1. No filtration was used for the Phase 1 used oil test. A reduced pan temperature at the 

point of smoke production results in more measureable smoke longer before ignition, reducing the 

challenges to prevention devices. The use of fresh oil would be more challenging for smoke detection 

devices. Similar results were observed for the oil temperatures at the time of smoke production, as 

shown in Figure 34. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 7 – Calculated pan and oil temperature slopes and obscuration slope and integrated areas for aged

Oil 

Average pan temp slope 

between fixed pan 

temperatures and ignition 

(°C/min) 

Average oil temp slope 

between fixed pan 

temperatures and ignition 

(°C/min) 

Difference between pan and oil 

temperature at fixed pan temps 

(°C) 

Int

250 °C

(482 °F)

300 °C

(572 °F)

350 °C

(662 °F)

375 °C

(707 °F)

250 °C

(482 °F)

300 °C

(572 °F)

350 °C

(662 °F)

375 °C

(707 °F)

250 °C

(482 °F)

300 °C

(572 °F)

350 °C

(662 °F)

375 °C

(707 °F)

IGN

250 °C

(482 °F)

P1 

Canola 35 31 25 20 42 38 33 31 63 58 51 50 32 0 

Aged Canola 36 31 25 26 44 40 39 37 62 57 58 40 24 1 

Peanut 40 35 29 24 51 47 45 42 132 125 120 113 87 0 

Aged Peanut 34 30 24 19 40 38 35 36 51 50 46 48 23 0 

Soybean 33 29 24 20 37 34 32 29 65 65 63 60 41 0 

Aged Soybean 35 31 26 25 43 39 36 28 62 54 43 28 26 1 

Used Soybean 36 33 29 26 38 36 32 16 34 36 30 19 26 9 

Corn 33 30 24 21 39 36 34 31 65 66 63 57 40 0 

Aged Corn 36 31 25 19 44 40 33 33 61 56 44 45 29 0 

Pork Lard 38 34 28 23 44 40 40 40 51 45 50 50 25 0 

Aged Lard 37 33 27 22 43 40 39 38 47 44 48 45 22 2 

P2 

Soybean 23 20 15 12 26 24 20 19 43 45 41 41 21 0 

Used Soybean 22 19 14 11 25 22 19 20 42 33 36 40 17 0 

Pork Lard 21 18 14 12 25 23 22 21 40 42 41 38 12 0 

Used Lard 20 17 14 12 24 22 19 19 39 42 38 35 12 0 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 46 

Figure 33 – Average pan temperature at 1.6 %/ft (5%/m) smoke measurement for aged/used oils 

Figure 34 – Average oil temperature at 1.6 %/ft (5 %/m) smoke measurement for aged/used oils 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 47 

The average oil temperature at smoke production was reduced from 274°C (525°F) for fresh oils to 

185°C (365°F) for the used deep fryer oil in Phase 1. The average oil temperature was reduced from 

289°C (552°F) for fresh oils to 261°C (502°F) for used oils in Phase 2. No such trend is observed for 

the artificially aged oils tested in Phase 1. The correlations and slopes of the pan and oil temperatures 

measured at smoke are shown in Figure 35. 

Figure 35 – Calculated correlations and slopes of pan and oil temperatures at smoke 

measurement and % FFA for used/aged oils 

While the pan and oil temperatures at smoke production were reduced with increasing % FFA for the 

used oils tested, little to no effect was observed for the temperatures at ignition. No distinguishable 

trend was observed for % FFA and ignition temperature over the range of tests conducted. The pan 

and oil temperature ranges measured at ignition are shown in Figures 36 and 37, respectively. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 48 

Figure 36 – Average pan temperatures at ignition for aged/used oils 

Figure 37 – Average oil temperatures at ignition for aged/used oils 

No consistent reduction in the pan or oil temperatures measured at ignition was observed for the aged 

or used oils tested in either phase. There is some variation observed in the pan temperatures, but the 

variations were within statistical variability. The oil temperatures measured at ignition were higher for 

the tests conducted in Phase 2, but this is believed to be due to more responsive thermocouples rather 

than the properties of the oils. There was almost no difference observed in the oil ignition temperatures 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 49 

for fresh, aged, or used oil in either test phase. This is also evidenced by the weaker correlations and 

lower slopes calculated for the pan and oil temperatures at ignition and % FFA shown in Figure 38. 

Figure 38 – Calculated correlations and slopes of pan and oil temperatures at ignition and

% FFA for used/aged oils 

6.5. Oil Brands 

Several tests were conducted to evaluate the impacts of the oil brand on the smoke and ignition 

properties. For implementation of a standard test, it is important to know whether the brand can impact 

the test results. The primary metrics of concern for comparison of the oil brands are the measured oil 

temperatures at the time of smoke production and at ignition. Tests were conducted in Phase 2 using 

four different brands of canola oils, including Great Value, Crisco, Wesson, and a generic brand. They 

were tested in a wide array of scenarios, including various pan types, ranges, and oil depths. When 

comparing oils throughout these scenarios, it was determined that there was no discernible difference 

in the smoke and ignition properties of oil by brand. 

The average oil temperatures measured when smoke levels of 1.6%/ft (5%/m) were measured in the 

hood are shown in Figure 39. The descriptions of each Scenario can be found in Table 2 in Section 5.3. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 50 

Figure 39 – Average oil temperature at 1.6%/ft (5%/m) smoke measurement for various brands of 

canola oils tested in Phase 2 for a range of cooking scenarios arranged by oil type (top) and test 

scenario (bottom) 

Although there is some variation between test scenarios, the average temperature for each oil brand is 

nearly identical. The average oil temperature at smoke production varies from 285°C (545°F) for Crisco 

to 289°C (552°F) for Great Value. Some tests measured oil temperatures at smoke production higher 

or lower than the other oils tested for the same scenarios, (e.g., Wesson in Scenario 10 or 13), but the 

variation is not consistent for the oil brand. The Wesson canola oil measured both higher and lower 

temperatures than the other oils, depending on the scenario. This would indicate the differences are 

more the result of test variability, than an inherent property of the oil brand. The primary differences 

between the test scenarios were identified for tests with a very long total heating time to ignition. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 51 

Scenario 10 (aluminum pan on glass ceramic range) and Scenario 13 (1/2 in. (12.7 mm) depth oil) were 

among the longest tests conducted, and resulted in the low smoke temperatures shown above. 

The average oil temperatures measured at ignition for the various canola oil brands are shown in 

Figure 40. The outliers observed for the smoke temperatures were not observed, and the average 

ignition temperatures range from 385°C (725°F) for Great Value and Crisco to 392°C (738°F) for the 

Generic brand. The increase in temperature in the generic oil is believed to result from a more limited 

test sample size, rather than any difference in the oil. Although some test to test variability was 

observed, no systematic differences were observed between the canola oil brands in smoke or ignition 

temperatures. 

Figure 40 – Average oil temperatures at ignition for various canola oil brands for a range of 

cooking scenarios arranged by oil type (top) and test scenario (bottom) 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 52 

Comparable results were observed for the Phase 1 tests conducted with commercial and consumer 

brand soybean and canola oils. The oil temperatures at smoke and ignition for Phase 1 tests are shown 

in Figures 41 and 42, respectively. The data shown represents only direct comparisons between oil 

types, with no other variables altered. Although the data samples were far more limited, the average 

pan and oil temperatures at smoke an ignition do not vary by more than a standard deviation for either 

oil type. 

Figure 41 – Average oil temperature at 1.6%/ft (5%/m) smoke measurement for various brands of 

soybean and canola oils tested in Phase 1 

Figure 42 – Average oil temperature at ignition for various brands of soybean and canola oils 

tested in Phase 1 

6.6. Pan Material 

A series of tests were conducted in Phase 2 to evaluate the differences between aluminum, stainless 

steel, and cast iron pans. Five 10 in. (25 cm) pan types were tested with canola oil on the 2600 W 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 53 

electric coil element, including two brands of 8 gauge aluminum pans, two brands of stainless steel 

pans, and a cast iron pan. The primary observations from testing multiple pan materials include: 

	 The low end brand of stainless steel pan heated and reached ignition much faster than the other 

pans tested, likely due to: 

o	 Very thin metal, light weight pan 

o	 Wider pan base than other 10 in. (25 cm) pans (8.5 in. (22 cm) v. 7.5 in. (19 cm)) 

o	 The time windows for operation of smoke or pan detection were proportional to the total 

heating time. The time windows could be reduced by reducing total heating time with: 

 Flatter pans 

 Wider pan base on element surface 

 More conductive pan metal 

 Lower specific heat capacity of pan 

 Less pan mass 

 The differences between the average pan and oil temperatures were consistent for all pans 

 The pan and oil temperatures at ignition were higher for tests reaching ignition faster 

o	 Highest for the low end stainless steel 

o	 Lowest for the aluminum pan 

All pan material evaluation tests were conducted on the 8 in. (20 cm) element of the 2600 W GE range, 

with a 10 in. (25 cm) pan and canola oil at a depth of 1⁄4 in. (6.4 mm). The tests included in the pan 

material analysis are listed in Table 8. Additional pan details are provided in Table 1 in Section 5.2.2. 

Table 8 – Tests included in pan material analysis 

Identifier Pan Used Test ID 

Aluminum 1 Vollrath 8 gauge aluminum pan 

P2-4 

P2-5 

P2-6 

Aluminum 2 Browne-Halco 8 gauge 

aluminum pan 

P2-4a 

P2-5a 

P2-6a 

Low End SS Tramontina stainless steel pan 

P2-16 

P2-17 

P2-18 

High End SS All-Clad stainless steel pan 

P2-19 

P2-20 

P2-21 

Cast Iron Lodge Cast Iron Pan 

P2-22 

P2-23 

P2-24 

6.6.1. Available Response Times 

Changes to the pan materials or manufactures were found to have a greater effect on the heating time 

to ignition than the oil types/brands/ages previously tested. The total heating time to ignition for the five 

pan material/brand tests are shown in Figure 43. The blue bars show the full range of heating times for 

each pan tested, while the red lines shows the mean time ±1 standard deviation for each pan. The 

green line and shaded region represent the mean time for all pans ±1 standard deviation. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 54 

Figure 43 – Heating times until ignition for pan materials/brands 

The low end stainless steel pan provided the fastest heating and ignition, igniting in an average of 388 

seconds. This pan had the lowest mass of all the pans and an 8.5 in. (21.6 cm) flat base diameter. All 

other 10 in. (25 cm) pans tested had a 7.5 in. (19.0 cm) flat base diameter. This extra surface area 

contacting the element may have caused the increase in heating rate. 

The two aluminum pans had the longest heating times to ignition, taking an average of 657 and 571 

seconds, respectively. Despite the extra mass of the cast iron pan, more than double the aluminum or 

high end stainless, the cast iron pan heated comparably but slightly faster than the high end stainless 

steel pan and the aluminum 2 (Browne-Halco) pans. The estimated specific heat of the cast iron (0.46 

J/g-K) was about half the aluminum (0.91 J/g-K) and slightly less than the stainless steel (0.51 J/g-K). 

This would imply that less energy is required on a mass basis to heat the pan, resulting in the reduced 

heating time for the cast iron pan. 

Faster or slower heating times to ignition can be attributed to a few independent test variables. The 

pans can be described by the flat diameter of the base, the pan mass, the specific heat capacity and 

conductivity, and the overall flatness of the pan. Each of these variables can impact the heat transfer 

rate to the pan and to the oil in the pan, affecting the heating time to ignition. 

The flatness of the pans have been measured using a flat bar and calipers along axes parallel and 

perpendicular to the handles. The deviation of the pan to the flat bar was measured along these axis at 

1 in. (2.5 cm) increments. The flatness was then characterized using two metrics. First, the radius of 

curvature of the pan base was calculated between the center of the pan and the outside of element. A 

smaller number indicates a more curved pan base over the element. The second metric calculated is 

the angle of tilt toward the pan handle relative to the pan resting flat on the element surface. These 

metrics are shown in the flatness curves for aluminum pan 1 (shown in Figure 44). 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 55 

Figure 44 – Measured flatness of aluminum pan 1 (Vollrath Arkadia) measured parallel to the 

handle 

This pan (Vorath Arkadia) was measured to have the smallest radius of curvature (46.4 in. (118 cm) 

and the largest angle of tilt (0.91°). It also produced the longest total heating times to ignition. The 

Browne-Halco Thermalloy aluminum pan was similar in shape but with a flattened curvature (187 in. 

(475 cm)) and reduced tilt angle (0.10°). The increased flatness and reduced tilt angle resulted in better 

contact with the element and a decrease of heating time to ignition. The base of this pan parallel to the 

handle is shown in Figure 45. 

Figure 45 – Measured flatness of aluminum pan 2 (Browne-Halco Thermalloy) measured parallel 

to the handle 

The low end stainless steel pan (Tramontina Everyday) with the shortest heating time to ignition had 

the largest flat base over the element, the greatest flatness over the element diameter (highest radius 

of curvature), and nearly no pan tilting to stabilize on the element (0.02°). The low end stainless pan 

base parallel to the handle is shown in Figure 46. 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 56 

Figure 46 – Measured flatness of the low end stainless steel pan (Tramontina Everyday) 

measured parallel to the handle 

The high end stainless steel pan (All-Clad Tri-Ply) had a slightly convex pan surface, making contact 

around the outer diameter and protruding slightly upward in the center. This stable outer ring resulted in 

a pan tilt angle of 0°. The base of the high end stainless steel pan is shown in Figure 47. 

Figure 47 – Measured flatness of the high end stainless steel pan (All-Clad Tri-Ply) measured 

parallel to the handle 

The cast iron pan (Lodge) also showed a slightly convex base, but with the protrusion pushing up 

between the center of the pan and the outer ring. This resulted in a small protruding torus ring around 

the pan. The flat outer ring preventing any tilting, and no angle was needed to stabilize the pan. The 

flatness of the cast iron pan is shown in Figure 48. 

Figure 48 – Measured flatness of the cast iron pan (Lodge) measured parallel to the handle 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 57 

The pan variables and a calculated correlation with the total heating time to ignition are shown in Table 9. 

The minimum possible heating time is calculated by combining the specific heat and mass of the pan, 

the specific heat, density, and volume of oil, and the output of the element as shown in Eq. (2) in 

Section 5.4.6. Scatter plots of the average heating time to ignition and several pan variables are shown 

in Figure 49. 

Table 9 – Variable associated with pan materials and correlation to heating time to ignition 

Pan 

Pan Base 

Diameter 

(in (cm)) 

Pan 

Mass 

(g (lb)) 

Specific 

Heat 

Capacity 

(J/g-K) 

Minimum 

Possible 

Heating 

Time 

(sec) 

Conductivity 

(W/m-K) 

Average 

Curvature 

(in (cm)) 

Pan 

Tilt 

(deg) 

Alum 1 7.5 (19.0) 817 (1.8) 0.91 188 215 51 (129) 0.91 

Alum 2 7.5 (19.0) 936 (2.1) 0.91 207 215 193 (489) 0.10 

Low end 

SS 7.5 (19.0) 694 (1.5) 0.51 131 54 1286 

(3266) 0.02 

High end 

SS 7.5 (19.0) 977 (2.2) 0.51 152 54 -69 (-175) 0.00 

Cast Iron 7.5 (19.0) 1970 

(4.3) 0.46 215 80 -12 (-31) 0.00 

Correlation 

to average 

heating 

time to 

ignition 

-0.91 0.15 0.59 0.62 0.65 -0.89 0.64 

Slope of 

average 

heating 

time to 

ignition 

-199 

(sec/in) 

0.03 

(sec/g) 

253 

(sec/(J/gK)) 

1.69 

(sec/sec) 

0.76 

(sec/(W/mK)) 

-0.15 

(sec/in) 

158 

sec/deg 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 58 

Figure 49 – Calculated correlations and slopes for heating time to ignition and pan variables 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 59 

The total heating time can be reduced by increasing the heat transfer rate between the pan and the 

element. This can be accomplished by using flatter pans with a wider base on the element, and using 

more conductive pans with lower specific heat capacity and mass. Most other measured test 

parameters are proportional to the total heating time to ignition. The time windows between reaching an 

average pan temperature of 300°C (572°F) during the heating process and ignition and a smoke 

obscuration of 1.6%/ft (5%/m) and ignition are shown in Figures 50 and 51, respectively. 

Figure 50 – Time window between pan temperature = 300°C (572°F) and ignition for various pan 

materials 

Figure 51 – Time window between smoke obscuration = 1.6%/ft (5%/m) and ignition for various 

pan materials 

Both the pan temperature and smoke windows were nearly proportional to the total heating time to 

ignition (see Figure 52). The pan temperature window correlated to within 1.00, and the smoke window 

to 0.98. There was more time available for activation by pan temperature = 300°C (572°F) than for 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 60 

smoke = 1.6%/ft (5%/m), as the time window for pan activation was 0.62 times the total heating time 

and the smoke window was 0.44 times the total heating time. 

Figure 52 – Correlations and slopes between smoke and pan temperature activation windows 

6.6.2. Temporal Heating Curves 

Temporal plots of the average pan and oil temperatures, and average smoke obscuration for the fastest 

(Low end SS) and slowest (Alum 1) pan materials are shown in Figure 53 aligned at the time of ignition 

(T = 0). The solid lines show the average for each material, and the dashed lines show the maximum 

and minimum values measured at the given time before ignition occurred. 

The measured pan and oil temperatures and smoke obscuration were higher longer before ignition for 

the slower aluminum pan test, increasing the available time windows for activation. It can be seen from 

the curves, however, that the pan and oil temperatures at the time of ignition were lower for the longer 

aluminum pan test than for the fast stainless steel tests. This is discussed in greater detail in 

Section 6.6.3. 

The calculated slopes in the pan and oil temperature curves, differences between the pan (center of 

pan) and oil (center of oil) temperatures at ignition, and the integrated smoke obscuration at fixed pan 

temperatures are shown in Table 10. The most challenging scenarios for each metric are highlighted. 

Several interesting effects can be seen from comparing the results of the data. The slope of the pan 

and oil temperature curves is much greater for the fast stainless steel test compared to the slow 

aluminum test. A difference of 30–40°C (54–72°F) per min was observed between the fastest and 

slowest tests. 

The difference between the pan and oil temperatures is much lower for the high end stainless steel and 

cast iron pans compared to the aluminum and low end stainless steel. This is due to the curvature of 

the pans. The center pan thermocouples were used for this analysis only, and the high end stainless 

steel and cast iron pans were found to have convex surfaces, with the center protruding away from the 

element. In these tests, the center thermocouples measured the lowest of the three pan thermocouples, 

resulting in much closer measurements to the oil temperatures. The pan temperatures in the high end 

stainless steel pan and in the cast iron pan at ignition are shown in Figure 54. 

The integral of the smoke obscuration is also nearly proportional to the total heating time to ignition. All 

pans were tested using fresh canola oil, and the smoke production rate was a function of the total test 

duration. The correlation and slope between the smoke integral and the total heating times are shown 

in Figure 55. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 61 

Figure 53 – Pan and oil temperatures and smoke obscuration curves for fastest (low end 

stainless steel – Tramontina Everyday) and slowest (Aluminum 1 – Vollrath Arkadia) pan 

materials aligned by ignition time 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 10 – Calculated pan and oil temperature slopes and obscuration slope and integrated areas for various 

Oil 

Average pan temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Average oil temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Difference between pan and oil 

temperature at fixed pan temps 

(°C) 

Integr

up to 

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

IGN

250°C

(482°F)

Aluminum 1 23 19 15 11 26 23 21 21 33 32 34 36 13 0 

Aluminum 2 29 25 20 16 33 29 28 27 33 31 35 34 15 0 

Low End SS 55 52 46 41 55 52 49 38 25 24 28 22 23 0 

High End SS 31 28 24 23 31 28 25 23 12 16 17 15 15 2 

Cast Iron 31 27 23 21 33 29 28 26 9 9 12 7 2 1 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 63 

TC1 located closest to handle, TC 2 in center of pan, and TC3 away from handle (see Figure 2) 

Figure 54 – Pan temperatures at ignition by location for the high end stainless steel and cast 

iron pans 

Figure 55 – Correlation and slope between the integrated smoke obscuration and total heating 

time to ignition 

6.6.3. Smoke Production and Ignition Temperatures 

The pan and oil temperatures measured at the time smoke was produced and at ignition provide a 

direct comparison of the impacts of the pans on the heating of oils. The average pan and oil 

temperatures at the time of low smoke measurements are shown in Figures 56 and 57, respectively. 

The pan and oil temperatures measured when low levels of smoke was measured were not strongly 

affected by the type of pan used or the resulting heating rate. The measured pan and oil temperatures 

were very consistent, varying by as much as 21°C (38°F) and 17°C (31°F) for the pan and oil, 

respectively. The strongest correlation for the pan and oil temperatures at smoke was observed for the 

conductivity of the pan. The pan temperature correlated to 0.71 with a slope of 0.07°C (0.13°F) per 

W/m-K, and the oil temperature correlated to 0.47 with a slope of 0.04°C (0.07°F) per W/m-K. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 64 

Figure 56 – Average pan temperature at 1.6%/ft (5%/m) smoke measurement for various pan 

materials 

Figure 57 – Average oil temperature at 1.6%/ft (5%/m) smoke measurement for various pan 

materials 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 65 

The average temperatures of the oil at the time the average pan temperature measured 300°C (572°F) 

are shown in Figure 58. Unlike the differences calculated and shown in Table 10, these values 

represent the bulk average oil temperature and the average of 3 pan temperature locations. 

Figure 58 – Average oil temperatures when pan temperature = 300°C (572°F) for various pan 

materials 

The average temperature of the oil measured when the pan reached a threshold of 300°C (572°F) was 

consistent for all pan materials, with all pans measuring an averaging temperature of 258°C (496°F) ± 

6°C (11°F). There was a wide range of variability in the low end stainless steel pan (237–291°C (459–556°F)), 

but the average fell in line with the other pan materials. This indicates that the pan temperature can 

provide a good estimate of the oil temperature regardless of the properties of the pan being used for 

testing. As discussed in Section 6.6.2, the location of the pan temperature measurement can impact the 

difference between the pan and oil temperatures. If a measurement is made where the pan does not 

make good contact with the element, the pan temperature may be lower and could underestimate the 

temperature of the oil. 

The average temperatures of the pan and oil at ignition do vary with the pan material. The impact 

appears to be linked to the total heating time to reach ignition. The pan and oil temperatures at ignition 

are shown in Figures 59 and 60, respectively. The blue bars represent every thermocouple in the pan 

plus minus 3 seconds from ignition in every test. There were spatial variations in the measured 

temperatures causing a wide range of values among all measurements. The center measurements 

were closest to the average measurements, but lower or higher temperatures were measured to the left 

or right of center as discussed in Section 8. The way the average temperature is affected by variables 

provides the best indication of the effect of the variable. The red bar shows the average, and the 

dashed red bars show the standard deviation from the average, a different interpretation with narrower 

bounds than the absolute maximum and minimum temperatures measured. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 66 

Figure 59 – Average pan temperatures at ignition for various pan materials 

Figure 60 – Average oil temperatures at ignition for various pan materials 

The pan and oil temperatures measured at ignition did vary for different pan materials, with the highest 

temperatures measured for the fastest tests (low end stainless steel) and the lowest temperatures 

measured for the slowest tests (aluminum 1). The pan and oil temperatures at ignition both correlated 

well with the total heating time to ignition, with correlation coefficients of -0.87 and -0.96 for the pan and 

oil temperatures, respectively. Although the changes were not drastic, -0.05°C per second for the pan 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 67 

temperatures and -0.03°C per second for the oil temperatures, the correlation was noticeable over the 

long differences in ignition times. These calculations are shown in Figure 61. 

Figure 61 – Correlation and slope between pan and oil temperatures at ignition 

and total heating time 

6.7. Ranges 

Testing was conducted to quantify the impacts of the element power input (Phase 1) and the element 

type (Phase 2). The intent of these tests were to determine how much the element or power setting 

would impact the heating times and ignition temperatures. The primary observations include: 

	 Lower element power output increases total heating times and windows for activation 

o	 Heating times could not be replicated by reducing the power on an element to “match” 

the power of a lesser element 

o	 When element power cycles, the total heating time to ignition is greatly increased 

 Observed both for turning the power level down and for automatic glass break 

sensor control 

 The pan dictates the impact of the glass ceramic radiant element vs. electric coil element 

o	 Aluminum pan much slower to ignition 

o	 Cast iron and stainless steel pans faster to ignition 

o	 May be due to flatness, radiative absorption, or other factors 

	 Test with slower heating rates have lower pan and oil temperatures at ignition 

The tests included in the range analysis are summarized in Table 11. The Phase 1 tests included the 

use of two brands of electric coil range with different power outputs, one scenario with the high power 

range turned down to “match” the lower power range, and one test with a small element. The Phase 2 

tests included aluminum, stainless steel, and cast iron pans on an electric coil range and on a higher 

power glass ceramic range element. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 68 

Table 11 – Tests included in range analysis 

Identifier Oil Type Description Test ID 

Phase 1 

2600 W 

Commercial Soybean Oil 

Browne-Halco 8 in. aluminum pan 

on GE 2600 W electric coil element 

on highest setting 

P1-1 

Commercial Canola Oil P1-5 

Commercial Canola Oil P1-6 

Crisco Vegetable Oil P1-10 

Crisco Canola Oil P1-11 

Wesson Vegetable Oil P1-12 

Wesson Canola Oil P1-13 

2100 W 

Commercial Soybean Oil Browne-Halco 8 in. aluminum pan 

on Frigidaire 2100 W coil element on 

highest setting 

P1-20 

Commercial Canola Oil P1-21 

2600 W set 

to 8.75 

Commercial Soybean Oil Browne-Halco 8 in. aluminum pan 

on GE 2600 W coil element with 

power lowered to 8.75 of 10, power 

cycle on/off with average power of 

2100 W 

P1-22 

Commercial Canola Oil P1-23 

1500 W Commercial Canola Oil 

Browne-Halco 8 in. aluminum pan 

on GE 1500 W coil element on 

highest setting 

P1-24 

Phase 2 

Alum - Coil 

Great Value Canola Oil Vollrath 10 in. aluminum pan on 

2600 W electric coil element 

P2-4 

Great Value Canola Oil P2-5 

Great Value Canola Oil P2-6 

Alum -

Smooth 

Great Value Canola Oil Vollrath 10 in. aluminum pan on 

3000 W glass ceramic element 

P2-25 

Wesson Canola Oil P2-26 

Crisco Canola Oil P2-27 

Great Value Canola Oil 

Brand new Vollrath 10 in. aluminum 

pan on 3000 W glass ceramic 

element 

P2-25a 

SS - Coil 

Great Value Canola Oil Tramontina 10 in. stainless steel pan 

on 2600 W electric coil element 

P2-16 

Wesson Canola Oil P2-17 

Crisco Canola Oil P2-18 

SS - Smooth 

Great Value Canola Oil Tramontina 10 in. stainless steel pan 

on 3000 W glass ceramic element 

P2-28 

Generic Canola Oil P2-29 

Crisco Canola Oil P2-30 

CI - Coil 

Wesson Canola Oil Lodge 10 in. Cast Iron pan on 2600 

W electric coil element 

P2-22 

Crisco Canola Oil P2-23 

Great Value Canola Oil P2-24 

CI - Smooth 

Great Value Canola Oil Lodge 10 in. Cast iron pan on 3000 

W glass ceramic element 

P2-31 

Generic Canola Oil P2-32 

Crisco Canola Oil P2-33 

6.7.1. Range Power Level (Phase 1) 

Fire tests were conducted in Phase 1 for two ranges with different maximum power levels and element 

coil designs. Tests were conducted at the maximum power level of one range (2600 W), and at the 

maximum power level of the other range (2100 W) on both range types. The higher power range was 

set to a element power of 8.75 (out of 10) in order to match the total power output of the elements. The 

element power was matched by reducing the element cycling time by 19%, as measured by total 

current. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 69 

In addition, a test was run on the small 6 in. (15 cm) 1500 W element of the higher power range at its 

maximum power setting. All Phase 1 range/element evaluation tests were conducted with an 8 in. 

(20 cm) diameter, 8 gauge aluminum frying pan. A total of 13.4 in.3 (220 mL) of oil was used for each 

test, resulting in an initial oil depth of 1⁄4 in. (6.4 mm). 

6.7.1.1. Available Response Times 

The total heating times required to reach ignition are shown in Figure 62. The time to ignition was 

observed to increase with decreasing range power, indicating a correlation of -0.57. The shortest time 

to ignition was observed for the GE range at its highest power setting for both canola and soybean oils. 

The 2100 W Frigidaire range produced ignition 62 and 95 seconds slower than the 2600 W GE for 

soybean and canola oil, respectively. When the power output of the GE range was reduced to 2100 W, 

however, the ignition times for the oils increased by 401 seconds and 317 seconds for soybean and 

canola oil, respectively. Despite matching the total power output between the two ranges, the ignition 

time was greater for the range with a coil operating with cyclic, rather than continuous heating. This 

effect may be due to the heat transfer rate of the element coil, but the GE range has more coils than the 

Frigidaire range and the ignition time for the 1500 W GE coil element with continuous heating was 

faster than the ignition time for the large element with cyclic heating. 

Figure 62 – Heating times until ignition for various range power levels 

The time windows between the pan temperature threshold and the smoke window scaled proportionally 

with the total heating times. The correlation of the total heating times to element heat output, and the 

pan and smoke time windows to total test time are shown in Figure 63. The pan temperature windows 

correlated to 1.00 with the total heating times, with a slope of 0.58 second window per second of total 

heating time. The smoke windows correlated to 0.99 with the heating time, with a slope of 0.44 second 

window per second of total heating time. The available window for the pan temperature threshold was 

consistently longer than for the smoke threshold. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 70 

Figure 63 – Correlation between the total heating time and element input power and the smoke 

and pan temperature time windows 

6.7.1.2. Temporal Heating Curves 

Temporal plots of the average pan and oil temperatures, and average smoke obscuration for the fastest 

and slowest pan materials are shown in Figure 64 aligned at the time of ignition (T = 0). The solid lines 

show the average for each material, and the dashed lines show the maximum and minimum values 

measured at the given time before ignition occurred. 

The curves shown represent the fastest (High Power (2600 W element)) and the slowest (Low Power 

(2600 W set to 8.75 power)) test conducted. There was greater variability observed for the high power 

tests, but this is due to the greater number of tests included. Slightly lower pan temperatures were 

measured at ignition for the low power tests. This is consistent with the results for slower tests 

observed in the analysis of other test variables. 

The calculated slopes in the pan and oil temperature curves, differences between the pan (center of 

pan) and oil (center of oil) temperatures at ignition, and the integrated smoke obscuration at fixed pan 

temperatures are shown in Table 12. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 71 

Figure 64 – Pan and oil temperatures and smoke obscuration curves for fastest and slowest 

element power outputs aligned by ignition time 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 12 – Calculated pan and oil temperature slopes and obscuration slope and integrated areas for various elem

Oil 

Average pan temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Average oil temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Difference between pan and oil 

temperature at fixed pan temps 

(°C) 

Integ

up to 

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

IGN

250°C

(482°F)

2600 W 34 30 24 20 40 36 32 30 64 61 56 54 36 0 

2100 W 31 27 24 22 37 34 29 26 48 44 29 28 17 0 

2600 W set 8.75 power 18 16 12 10 22 19 17 16 49 38 38 36 19 0 

1500 W 11 9 6 4 13 11 8 8 46 46 41 40 22 0 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 73 

Although the total heating time to ignition was shorter for the test with the 1500 W element than with the 

2600 W element turned down, the slope of the pan and oil temperatures was actually lower. This test 

also had the greatest integrated smoke production. There was little to no trend observed for the 

differences between the pan and oil temperatures measured at fixed pan temperatures for the various 

element power outputs. 

6.7.1.3. Smoke Production and Ignition Temperatures 

The pan and oil temperatures at the time smoke obscuration measured 1.6%/ft (5%/m) are shown in 

Figures 65 and 66, respectively. The oil temperatures were observed to increase slightly with 

decreasing range power output, and therefore with increasing total time to ignition. No visible trend was 

observed for the pan temperatures, however. 

Figure 65 – Average pan temperature at 1.6%/ft (5%/m) smoke measurement for element power 

outputs 

Figure 66 – Average oil temperature at 1.6%/ft (5%/m) smoke measurement for element power 

outputs 

The increase in oil temperatures without a corresponding increase in the pan temperatures at smoke 

can also be observed when the pan temperature reached 300°C (572°F). The measured oil 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 74 

temperatures increased with longer tests/lower power given a fixed pan temperature measurement. 

The oil temperatures at this pan temperature are shown in Figure 67. 

Figure 67 – Average oil temperature when pan = 300°C (572°F) for various element power 

outputs 

The calculated correlations between the total heating time to ignition and the pan and oil temperatures 

at smoke measurement, and the oil temperatures at 300°C (572°F) pan measurement are shown in 

Figure 68. As shown, there is little to no correlation in the pan temperature at smoke, but the measured 

oil temperatures at the smoke and pan thresholds were observed to increase with the duration of the 

tests. 

Figure 68 – Correlations and slopes for total heating time and pan and oil temperatures at 

smoke production and oil temperatures at fixed pan temperature 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 75 

The pan and oil temperatures at the time of ignition are shown in Figures 69 and 70, respectively. The 

pan temperatures were observed to decrease slightly with decreasing range power output, and 

therefore with increasing total time to ignition. No visible trend was observed for the oil temperatures, 

however. This is the opposite effect observed for the pan and oil temperatures at the time of smoke 

production. 

Figure 69 – Average pan temperature at ignition for various element power outputs 

Figure 70 – Average oil temperature at ignition for various element power outputs 

The calculated correlations between the pan and oil temperatures at ignition and the total heating time 

to ignition are shown in Figure 71. A strong negative correlation was observed in the pan temperature 

with a small slope of -0.03°C/sec, and almost no relationship was observed for the oil temperatures at 

ignition. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 76 

Figure 71 – Correlations and slopes for total heating time and pan and oil temperatures at 

ignition for various element powers 

6.7.2. Range Type (Phase 2) 

Fire tests were conducted in Phase 2 for an electric coil range with a 2600 W element and for a glass 

ceramic top range with 3000 W element. All Phase 2 range evaluation tests were conducted in a 10 in. 

(25 cm) diameter, aluminum, stainless steel, and cast iron frying pans. A total of 18.3 in.3 (300 mL) of 

oil was used for each test, resulting in an initial oil depth of 1⁄4 in. (6.4 mm). 

6.7.2.1. Available Response Times 

The total heating time to ignition for each pan tested on the coil range and the glass ceramic range is 

shown in Figure 72. For the glass ceramic range, the aluminum pan had an increased total ignition time 

compared to the coil range, while the stainless steel and cast iron pans both heated faster on the glass 

ceramic range top. 

Figure 72 – Heating times until ignition for coil and glass ceramic (smooth) top ranges 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 77 

The aluminum pan heated much more slowly because the glass break sensor in the range began to 

cycle the power on and off, reducing the total power input. This effect is described in more detail in 

Section 6.7.2.2. With the power cycling on and off, the average power output during the aluminum pan 

tests on the glass ceramic top range dropped from 3000 W to approximately 2000 W. When making 

this adjustment for the range output, the total heating time to ignition and the range power correlate to ­

0.89 at a slope of -0.7 sec/W of power as shown in Figure 73. 

Figure 73 – Correlation and slope between range input power and total heating time to ignition 

for coil and glass ceramic (smooth) top tests 

The time windows between the pan temperature and smoke thresholds and ignition scaled 

proportionally to the total heating times for each test (see Figure 74). Both correlate nearly exactly with 

the total heating time, with the pan temperature window slightly longer than the smoke window. 

Figure 74 – Correlation and slope between total heating time to ignition and pan temperature 

and smoke windows to ignition for coil and glass ceramic top tests 

6.7.2.2. Temporal Heating Curves 

There was a wide range in total heating time to ignition for the coil and glass ceramic top tests. The pan 

and oil temperatures and smoke obscuration of the longest (aluminum on glass ceramic top) and 

shortest (stainless steel on glass ceramic top) tests are shown in Figure 75. 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 78 

Figure 75– Pan and oil temperatures and smoke obscuration curves for fastest and slowest 

range types aligned by ignition time 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 79 

A sensor in the glass ceramic top glass began to cycle the element power on and off during the 

aluminum pan tests. When the element power began cycling, the average power was reduced to 

1750 W, resulting in a test average power of 2010 W. The stainless steel pan reached ignition after one 

to two power cycles, and the cast iron pan reached ignition before activation of the sensor. As a result, 

the times to ignition for the stainless and cast iron pans were reduced compared to the electric coil, 

while the time to ignition was greatly increased for the aluminum pan. The pan and oil temperatures 

from one of the aluminum pan on glass ceramic top range tests and the range power values are shown 

in Figure 76. 

Figure 76 – Pan and oil temperatures and range power during an aluminum pan on glass 

ceramic range test 

During testing, it was believed that the significant increase in aluminum heating time could have been a 

result of damage to the pan caused by repeated testing. A test on the glass ceramic top range was 

conducted using a brand new pan. This pan had slightly less curvature than the used pan (56.4 in. 

(143 cm) compared to 50.8 in. (129 cm) for the used pan) and slightly less tilt angle (0.36° v. 0.91° for 

the used pan). The heating time to reach ignition and the heating rates were nearly identical (1108 

seconds for the new pan v. 1026,1137, and 1109 seconds for the three used pan tests), and this test is 

included in the temporal curves shown in Figure 75. The significant increase in heating time was not 

related to the aluminum pan flatness or tilt, and the new pan responded the same as a used pan. 

The calculated slopes in the pan and oil temperature curves, differences between the pan (center of 

pan) and oil (center of oil) temperatures at ignition, and the integrated smoke obscuration at fixed pan 

temperatures are shown in Table 13. The metrics indicative of the greatest challenges for detection 

devices are highlighted. The slopes of the pan and oil temperatures are reduced for the longer tests, as 

evidenced by the glass ceramic top aluminum pan tests. These tests also had significantly more 

integrated smoke obscuration than the faster tests conducted. 

A very small difference (2–12°C (4–22°F)) was measured between the pan and oil temperatures in the 

cast iron pan on the electric coil range. This difference is attributed to reduced pan temperatures 

measured in the center of the pan resulting from the convex shape of the pan as discussed in Section 

6.6.2. This effect was not observed for the glass ceramic top range tests with the same pan, however. 

This may be a result of more even heating from radiant exposure than for conductive contact. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 13 – Calculated pan and oil temperature slopes and obscuration slope and integrated areas for various coil and g

Oil 

Average pan temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Average oil temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Difference between pan and oil 

temperature at fixed pan temps 

(°C) 

Integ

up to 

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

IGN

250°C

(482°F)

Alum - Coil 23 19 15 11 26 23 21 21 33 32 34 36 13 0 

Alum -Smooth 11 9 6 4 13 11 8 8 46 46 41 40 22 0 

SS - Coil 55 52 46 41 55 52 49 38 25 24 28 22 23 0 

SS - Smooth 59 55 49 45 61 52 49 50 47 34 41 47 42 0 

CI - Coil 31 27 23 21 33 29 28 26 9 9 12 7 2 1 

CI - Smooth 47 43 37 33 49 48 47 43 39 46 51 45 31 0 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 81 

6.7.2.3. Smoke Production and Ignition Temperatures 

The pan and oil temperatures at the time smoke obscuration measured 1.6%/ft (5%/m) are shown in 

Figures 77 and 78 respectively. In addition to the full range, average, and standard deviation for each 

test scenario, the average and standard deviation among all electric coil tests and all glass ceramic 

tests are shown for relative comparison. The pan temperatures were observed to decrease with the 

increasing ignition time for the aluminum, stainless steel, and cast iron pans. The aluminum pans took 

longer to ignite on the glass ceramic top range (decreasing pan temperature) while the cast iron and 

stainless steel pans ignited faster (increasing pan temperatures). 

Figure 77 – Average pan temperature at 1.6%/ft (5%/m) smoke measurement for electric coil and 

glass ceramic (smooth) top ranges 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 82 

Figure 78 – Average oil temperature at 1.6%/ft (5%/m) smoke measurement for electric coil and 

glass ceramic (smooth) top ranges 

The measured temperature of the oil at smoke production also decreased for the longer aluminum pan, 

glass ceramic top range tests. For the stainless steel and cast iron pans on glass ceramic top ranges, 

there was an increase in measured pan temperatures (for faster tests) without a corresponding 

increase in the oil temperatures at smoke production. This would imply that the increased element 

power causes more heat transfer from the pan to the oil, resulting in a greater temperature gradient. 

The physical properties of the oil are not changed, and so the production of smoke stills occurs at the 

same oil temperature. Conversely, the extremely slow heating rate of the aluminum pan on the glass 

ceramic top range may actually result in a breakdown of the oil, causing reduced oil smoke 

temperatures as was observed for aged and used oils analyzed in Section 6.4. 

The increased temperature gradient at high heating rates can be observed from the reduced oil 

temperatures measured at a fixed pan temperature value of 300°C (572°F) (see Figure 79). The slower 

heating electric coil tests conducted with the stainless steel and cast iron pans resulted in increased 

measured oil temperatures with respect to fixed pan temperatures. A device measuring a fixed pan 

temperature would therefore allow higher oil temperatures to occur for reduced heating rates, which 

may be a more challenging condition for fire prevention. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 83 

Figure 79 – Average oil temperature when pan = 300°C (572°F) for electric coil and glass ceramic 

(smooth) top ranges 

The calculated correlations between the total heating time to ignition and the pan and oil temperatures 

at smoke measurement, and the oil temperatures at 300°C (572°F) pan measurement are shown in 

Figure 80. While the calculated correlations do show the relationships discussed above, the magnitude 

of the changing temperatures with respect to ignition time are extremely small (0.01 to 0.03°C change 

per second of heating time). 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 84 

Figure 80 – Correlations and slopes for total heating time and pan and oil temperatures at 

smoke production and oil temperatures at fixed pan temperature 

The pan and oil temperatures at the time of ignition are shown in Figures 81 and 82, respectively. The 

pan temperatures were observed to decrease slightly with increasing total time to ignition. This is 

demonstrated by the decrease in pan temperature for the aluminum pan from coil to glass ceramic top 

range (slower test), and the increase in pan temperature for the stainless steel and cast iron pans from 

coil to glass ceramic top range (faster tests). 

The oil temperatures measured at ignition decreased for all three pan types on the glass ceramic top 

range compared to the coil. It is possible that the reduced overall pan temperatures at ignition for the 

slow aluminum pan on glass ceramic top also resulted in lower oil temperatures at ignition, while the 

increased heat transfer rates for the fast stainless steel and cast iron on glass ceramic top tests 

resulted in greater gradients and therefore reduced oil temperatures. The observed effects may also 

have been the result of random test variation, as the changes in average oil temperature were within 

one standard deviation for the stainless steel and cast iron pans. The change in the oil temperature for 

the aluminum pan is greater than one deviation in magnitude, and is likely related to the increased total 

heating time to reach ignition. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 85 

Figure 81 – Average pan temperature at ignition for various element power outputs 

Figure 82 – Average oil temperature at ignition for various element power outputs 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 86 

The calculated correlations between the pan and oil temperatures at ignition and the total heating time 

to ignition are shown in Figure 83. Strong negative correlations were observed in both the pan and oil 

temperatures at ignition relatively small slopes of -0.04°C/sec and 0.02°C/sec, respectively. 

Figure 83 – Correlations and slopes for total heating time and pan and oil temperatures at 

ignition for various element powers 

6.8. Oil Depth 

A series of tests were conducted in Phase 2 to evaluate the impacts of increasing the depth of oil. Tests 

were conducted with 1⁄4 in. (6.4 mm) and 1⁄2 in. (12.8 mm) depths of canola oil in 10 in. (25 cm) 

aluminum and stainless steel pans on the 2600 W electric coil element. The primary observations from 

testing deeper oils include: 

 The additional mass of oil slows the heating process and the tests take longer to reach ignition 

 Most metrics correlate well with the total heating time to ignition 

o	 Total heating time to ignition correlates well with the combined pan and oil heat 

capacities (minimum possible heating time, see Eq. (2) in Section 5.4.6) 

o	 Time window for smoke or pan temperature activation 

o	 Pan and oil temperatures at smoke production and ignition reduced with increased 

heating time 

o Difference between pan and oil temperature increased with longer heating times 

 The temperature of the oil is nearly uniform as a function of oil depth
 

All oil depth tests included in this analysis use the 10 in. (25 cm) Vollrath aluminum pan or the 

Tramontina (low end) stainless steel pan. Tests were conducted at only two oil depths. The tests 

included in the oil depth analysis are listed in Table 14. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 87 

Table 14 – Tests included in oil depth analysis 

Identifier Oil Type Description Test ID 

Alum – 1/4 

Great Value Canola Oil Vollrath aluminum pan with 1⁄4 in (6.4 

mm) canola oil on 2600 W coil 

P2-4 

Great Value Canola Oil P2-5 

Great Value Canola Oil P2-6 

SS – 1/4 

Great Value Canola Oil Tramontina stainless steel pan with 

1⁄4 in (6.4 mm) canola oil on 2600 W 

coil 

P2-16 

Wesson Canola Oil P2-17 

Crisco Canola Oil P2-18 

Alum – 1/2 

Crisco Canola Oil Vollrath aluminum pan with 1⁄2 in 

(12.8 mm) canola oil on 2600 W coil 

P2-37 

Great Value Canola Oil P2-38 

Wesson Canola Oil P2-39 

SS – 1/2 

Great Value Canola Oil Tramontina stainless steel pan with 

1⁄2 in (12.8 mm) canola oil on 2600 

W coil 

P2-40 

Wesson Canola Oil P2-41 

Wesson Canola Oil P2-42 

6.8.1. Available Response Times 

The total heating time to reach ignition was increased by increasing the depth of oil tested. The average 

times to ignition for the four test scenarios are shown in Figure 84. The average time to ignition for the 

1⁄4 in. (6.4 mm) depth tests was 522, which increased to 776 seconds for the 1⁄2 in. (12.8 mm) oil depths. 

Figure 84 – Heating times until ignition for multiple oil depths 

The heating time to ignition has been related to both the depth of the oil and the minimum possible 

heating time as shown in Figure 85. Increases in heating times were observed for increasing oil depth 

for the aluminum (1284 sec/in.) and the stainless steel (743 sec/in.). The minimum possible heating 

time is a calculated estimate of the ignition time based on pan and oil material properties and element 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 88 

power (see Eq. (2) in Section 5.4.6). This calculation accounts for the differences between the 

aluminum and stainless steel pans, allowing for calculation of a correlation to total heating time to 

ignition. Correcting for the pan material properties, the measured heating time correlates to 0.96 with 

the calculated minimum heating time, with a slope of 4.6 seconds of heating per calculated minimum 

second. 

Figure 85 – Correlation between the total heating time to ignition and the oil depth (left plot) and 

calculated minimum heating time to ignition (right plot including both AL and SS pans) 

The time windows available between a fixed pan temperature of 300°C (572°F) and ignition or smoke 

obscuration of 1.6%/ft (5%/m) and ignition scaled proportionally with the total time to ignition. The 

correlation and calculated slopes for these parameters are shown in Figure 86. 

Figure 86 – Correlation between the total heating time to ignition and the pan and smoke time 

windows to ignition 

Both time windows correlate nearly proportionally (0.99 and 1.00) and with comparable slopes of 0.59 

and 0.58 seconds of window per second of total heating time. These available time windows are 

independent of the differences between the two pans tested. 

6.8.2. Temporal Heating Curves 

Temporal plots of the average pan and oil temperatures, and average smoke obscuration for the fastest 

(stainless steel with 1⁄4 in. of oil) and slowest (aluminum with 1⁄2 in. of oil) of the oil depth tests are shown 

in Figure 87 aligned at the time of ignition (T = 0). The solid lines show the average for each material, 

and the dashed lines show the maximum and minimum values measured at the given time before 

ignition occurred. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 89 

Figure 87 – Pan and oil temperatures and smoke obscuration curves for fastest and slowest oil 

depths aligned by ignition time 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 90 

As shown in the temporal curves, there is a large disparity in ignition times between the aluminum pan 

with 1⁄2 in. (12.8 mm) of oil and the stainless steel pan with 1⁄4 in. (6.4 mm) of oil. The longer test 

scenario has lower measured pan and oil temperatures at the time of ignition. This is a trend observed 

through several other evaluated variables, including pan materials and range power/type. In almost all 

cases tested, tests taking longer to reach ignition also measured lower temperatures at ignition. 

The calculated slopes in the pan and oil temperature curves, differences between the pan (center of 

pan) and oil (center of oil) temperatures at ignition, and the integrated smoke obscuration at fixed pan 

temperatures are shown in Table 15. The most challenging test conditions are highlighted for each 

metric evaluated. The shallower oil provided greater challenges for the aluminum pan for all metrics 

considered. The shallower oil also provided greater challenges for the stainless steel pan for all metrics 

except the difference between the pan and oil temperatures, which were nearly the same for both oil 

depths, varying by less than 6°C. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 15 – Calculated pan and oil temperature slopes and obscuration slope and integrated areas for multiple 

Oil 

Average pan temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Average oil temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Difference between pan and oil 

temperature at fixed pan temps 

(°C) 

Integra

up to 

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

IGN

250°C

(482°F)

Alum – 1/4 23 19 15 11 26 23 21 21 33 32 34 36 13 0 

Alum – 1/2 14 12 9 6 17 15 14 13 50 46 44 44 18 3 

SS – 1/4 55 52 46 41 55 52 49 38 25 24 28 22 23 0 

SS – 1/2 31 28 26 23 33 30 28 27 28 25 22 22 17 1 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 92 

6.8.3. Smoke Production and Ignition Temperatures 

The pan and oil temperatures at the time smoke obscuration measured 1.6%/ft (5%/m) are shown in 

Figures 88 and 89, respectively. In addition to the full range, average, and standard deviation for each 

test scenario, the average and standard deviation among the 1⁄4 in (6.4 mm) and 1⁄2 in (12.8 mm) depths 

for both pans are shown for relative comparison. The pan and oil temperatures were observed to 

decrease with an increase in oil depth for the aluminum pan (-29°C (52°F) pan, -38°C (68°F) oil). 

Comparable effects were not observed for the stainless steel pan, with the pan temperature increasing 

by 7°C (13°C) and the oil temperature decreasing by 3°C (5°F). 

Figure 88 – Average pan temperature at 1.6%/ft (5%/m) smoke measurement for multiple oil 

depths 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 93 

Figure 89 – Average oil temperature at 1.6 %/ft (5%/m) smoke measurement for multiple oil 

depths 

The measured oil temperatures when the pan temperature reached 300°C (572°F) decreased for both 

pan types with an increase in the oil depth. The oil temperatures at this pan temperature are shown in 

Figure 90. The average oil temperature decreased for deeper oil by 7°C (13°F) and 11 °C (20°F) for the 

aluminum and stainless steel pans, respectively. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 94 

Figure 90 – Average oil temperature when pan = 300°C (572°F) for multiple oil depths 

The calculated slope between the total heating time to ignition and the pan and oil temperatures at 

smoke measurement for each individual test, and the oil temperatures at 300°C (572°F) pan 

measurement are shown in Figure 91. The measured temperatures were all observed to decrease with 

increasing total time to ignition and oil depth except for the pan temperature at smoke for the stainless 

steel pans. The pan and oil temperatures at the time 1.6%/ft (5%/m) smoke was measured decreased 

in the aluminum pans by 5.4 and 6.9°C (9.7 and 12.4°F) per additional minute of heating time to 

ignition, respectively. The average oil temperature when the average pan temperature reached 300°C 

(572°F) also decreased with increasing total heating time to ignition. This effect was observed for both 

pan materials, with the average oil temperature decreasing by 1.3 and 3.5°C (2.3 and 6.3°F) per minute 

of heating time to ignition for the aluminum and stainless steel pans, respectively. This effect implies 

that the bulk oil temperature is greater at a given pan temperature threshold for tests conducted with 

less oil depth. A greater oil temperature at a fixed pan temperature would provide a greater challenge to 

devices using pan temperature sensing technologies. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 95 

Figure 91 – Slopes for total heating time and pan and oil temperatures at smoke production and 

oil temperatures at fixed pan temperature for multiple oil depths 

The pan and oil temperatures at the time of ignition are shown in Figures 92 and 93, respectively. The 

pan and oil temperatures were observed to decrease slightly (3°C (5°F) for pan, 6–12°C (11–22°F) for 

oil) for both aluminum and stainless steel pans with increased oil depth, and therefore with increasing 

total time to ignition. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 96 

Figure 92 – Average pan temperature at ignition for multiple oil depths 

Figure 93 – Average oil temperature at ignition for multiple oil depths 

The calculated slopes between the pan and oil temperatures at ignition and the total heating time to 

ignition for each test are shown in Figure 94. Both the pan and oil temperatures at ignition decreased 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 97 

with increased heating time, and therefore oil depth. This was observed for both aluminum and 

stainless steel pans. The average pan and oil temperatures at ignition in aluminum pans decreased by 

0.6 and 1.2°C (1.1 and 2.2°F) per minute of heating time, respectively. The effect was slightly greater 

for the stainless steel pans, with the average pan and oil temperatures decreasing by 0.8 and 3.0°C 

(1.4 and 5.4°F) per minute of heating, respectively. Obviously this trend would not continue indefinitely 

and would asymptotically approach a minimum oil ignition temperature. 

Figure 94 – Correlations and slopes for total heating time and pan and oil temperatures at 

ignition for multiple oil depths 

For tests with a 1⁄2 in. (12.8 mm) depth of oil, the thermocouples were separated vertically by 1⁄8 in. 

(3.2 mm) for each oil temperature location. This was expanded from the 1/32 (0.8 mm) spacing 

evaluated for the 1⁄4 in. (6.4 mm) oil depth tests. The intent of expanding this spacing was to determine 

the impact of insertion depth on the measured oil temperatures with a more proportional variation for 

the larger oil depth. The range of oil thermocouple temperatures measured at all locations for a 1⁄2 in. 

(12.8 mm) depth test (P2-37) are shown at the time the pan temperature reached 300°C (572°F), the 

time smoke obscuration of 1.6%/ft (5%/m) was measured, and at ignition in Figure 95. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 98 

Figure 95 – Oil temperatures measured across all spatial locations for a test with 1⁄2 in. (12.8 mm) 

oil depth 

The oil temperature designations in the figure describe locations one, two, and three, which are spread 

laterally across the pan. The designations + and – indicate that the thermocouple was located above or 

below the half depth of the oil, respectively. While there is some variation in the oil temperature 

measurements by lateral position (approximately 10°C (18°F), there is little variation among the 

thermocouples at different heights in the oil (approximately 1–2°C (1.8–3.6°F). The variability between 

the vertical oil temperature measurements is less at ignition compared to earlier in the test, indicating a 

more vertically uniform oil temperature. The uncertainty of the thermocouples in these temperature 

ranges is approximately 2.2°C (4.0°F), and the difference in vertical temperature is comparable to this 

value. 

6.9. Pan Thickness and Diameter 

A series of tests were conducted in both Phase 1 and Phase 2 to determine the impacts of pan 

diameter and thickness on the heating rates and measured pan and oil temperatures. The primary 

observations of the pan thickness and diameter tests show: 

	 The heating time to ignition increases for larger and thicker pans 

o	 Pans smaller than the element increase heating time compared to pans approximately 

the same size as element 

o	 Pans much larger than the element do not heat the pan surface evenly, measuring 

higher temperatures in the center 

 Ignition times can vary greatly for the largest pans 

 Ignition times ranged from 20 minutes to 1 hour, and one test did not ignite after 

1 hour of heating 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009	 PAGE 99 

o	 The available time windows for operation of pan or smoke measuring devices are 

directly proportional to the total heating time to ignition 

	 The pan temperatures measured at ignition and at smoke production were reduced for tests 

with longer total heating times compared to shorter tests 

o	 The oil temperatures were relatively unaffected by the length of the test 

o	 Ignition at lower pan temperatures with the same oil temperature may increase 

challenge for detection 

The tests included in the pan size evaluation are summarized in Table 16, include all tests conducted 

with 8 gauge aluminum pans on the 2600 W electric coil element using either soybean or canola oils. 

Pans sizes ranged from 7 in. (18 cm) to 14 inch (36 cm). The brand of the aluminum pans was found to 

have an impact on the total heating time for the same size and thickness (see Section 6.6), and multiple 

brands were tested in this analysis due to availability. The brand (either Vollrath (V), or Browne-Halco 

(BH)) have been noted in the test identifiers. 

The tests included in the pan thickness evaluation are also summarized in Table 16. These tests 

include the Phase 2 tests conducted with the 10 inch Browne-Halco pans of 8 and 10 gauge, 

thicknesses. In addition, all Phase 1 tests conducted with 8 in. (20 cm) aluminum pans on the 2600 W 

electric coil range using either corn oil or pork lard are included. The tests included both Vollrath 

(10 gauge and 8 gauge) pans, and Browne-Halco (5 gauge) pans due to availability. 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 100 

Table 16 – Tests included in pan size/thickness analysis 

Identifier Oil Type Description Test ID 

Pan Size Evaluation 

7 inch 

(V) 

Commercial Canola 180 mL of oil in 7 in., 8 gauge 

Vollrath aluminum pan 

P1-25 

Commercial Soybean P1-26 

8 inch 

(BH) 

Commercial Soybean Oil 220 mL of oil in 8 in., 8 gauge 

Browne-Halco aluminum pan 

P1-1 

Commercial Canola Oil P1-5 

Commercial Canola Oil P1-6 

10 inch 

(V) 

Great Value Vegetable Oil 

300 mL of oil in 10 in., 8 gauge 

Vollrath aluminum pan 

P2-1 

Great Value Vegetable Oil P2-2 

Great Value Vegetable Oil P2-3 

Great Value Canola Oil P2-4 

Great Value Canola Oil P2-5 

Great Value Canola Oil P2-6 

10 inch 

(BH) 

Great Value Canola Oil 300 mL of oil in 10 in., 8 gauge 

Browne-Halco aluminum pan 

P2-4a 

Crisco Canola Oil P2-5a 

Generic Canola Oil P2-6a 

14 inch 

(V) 

Commercial Canola Oil 600 mL of oil in 14 in., 8 gauge 

Vollrath aluminum pan 

P1-27 

Commercial Soybean Oil P1-28 

14 inch 

(BH) 

Great Value Canola Oil 600 mL of oil in 14 in., 8 gauge 

Browne-Halco aluminum pan 

P2-43 

Wesson Canola Oil P2-44 

Wesson Canola Oil P2-45* 

*Test P2-45 did not ignition after 1 hour of heating and the test was stopped, the 

results are presented but not included in the average test results 

Pan Thickness Evaluation 

10 inch diameter pans 

10 gauge 

(10-V) 

Great Value Canola Oil 300 mL of oil in 10 in., 10 gauge 

Vollrath aluminum pan 

P2-34 

Wesson Canola Oil P2-35 

Generic Canola Oil P2-36 

8 gauge 

(10-BH) 

Great Value Canola Oil 300 mL of oil in 10 in., 10 gauge 

Vollrath aluminum pan 

P2-4 

Crisco Canola Oil P2-5 

Generic Canola Oil P2-6 

8 inch diameter pans 

10 gauge 

(8-V) 

Commercial Corn Oil 220 mL of oil in 8 in., 10 gauge 

Vollrath aluminum pan 

P1-31 

Commercial Pork Lard P1-32 

8 gauge 

(8-BH) 

Commercial Corn Oil 

220 mL of oil in 8 in., 8 gauge 

Browne-Halco aluminum pan 

P1-2 

Commercial Corn Oil P1-3 

Commercial Corn Oil P1-4 

Commercial Pork Lard P1-9 

5 gauge 

(8-BH) 

Commercial Corn Oil 220 mL of oil in 8 in., 5 gauge 

Browne-Halco aluminum pan 

P1-29 

Commercial Pork Lard P1-30 

6.9.1. Available Response Times 

The average times to ignition for the pan size and thickness tests are shown in Figure 96. The ignition 

times for the 14 in. (36 cm) pan tests were highly variable and much longer than the other scenarios 

tested. The ignition times are also shown in Figure 97 with the time axis zoomed in to compare the 

shorter test scenarios. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 101
 

Figure 96 – Heating times until ignition for pan size (top) and thickness (bottom) tests 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 102 

Figure 97 – Heating times until ignition for pan size/thickness tests with reduced time axis 

The fastest heating times to ignition were achieved for the 8 in. (20 cm), 8 gauge Browne-Halco pan. 

Increasing the pan size (and total oil volume) increased the ignition time from this value. Conversely, 

decreasing the pan size and oil volume also increased the total ignition time. This is likely due to 

reduced element coverage and loss of input power, although may also have been the result of 

changing the brand of the pan. The large 14 in. (36 cm) pans extended well beyond the element 

surface, making ignition timing highly variable. The temperature increases were very slow at the end of 

these tests, and slight variations in ignition temperature could increase the length of a test by many 

minutes. One 14 in. (36 cm) test conducted did not reach ignition (P2-45) after an hour of heating. 

The heating time to ignition has been correlated to the diameter of the pan and the thickness of the pan 

for the separate tests considered. In addition, all tests have been correlated to the minimum possible 

heating time as shown in Figure 98. The minimum possible heating time is a combination of the pan 

and oil mass and element heat output (see Eq. 2 in Section 5.4.6). The heating time to ignition 

increases with both pan diameter (approximately 246 sec per inch diameter) and pan thickness (900– 

1200 sec per inch thickness). When the pan thickness and diameters are combined in the minimum 

possible heating time, a correlation to total heating time of 0.80 with a slope of 6.3 seconds heating 

time per minimum second is calculated as shown. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 103 

Figure 98 – Correlation between the total heating time to ignition and pan size/thickness and 

calculated minimum heating time to ignition 

The time windows available between a fixed pan temperature of 300°C (572°F) and ignition or smoke 

obscuration of 1.6%/ft (5%/m) and ignition scaled proportionally with the total time to ignition. The 

correlation and calculated slopes for these parameters are shown in Figure 99, both correlating to 1.00 

with average slopes of 0.80 and 0.78 sec window per second heating time for smoke and pan 

temperature, respectively. These available time windows are independent of the differences between 

the pan sizes or thicknesses. 

Figure 99 – Correlation between the total heating time to ignition and the pan and smoke time 

windows to ignition for pan size/thickness tests 

6.9.2. Temporal Heating Curves 

Temporal plots of the average pan and oil temperatures, and average smoke obscuration for the fastest 

and slowest of the oil depth tests are shown in Figure 100 aligned at the time of ignition (T = 0). The 

solid lines show the average for each material, and the dashed lines show the maximum and minimum 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 104 

values measured at the given time before ignition occurred. Due to the high level of variability, the 

average curve for the 14 in (36 cm) pan tests is not shown, only the maximum and minimum curves. 

Figure 100 – Pan and oil temperatures and smoke obscuration curves for fastest and slowest 

pan size/thickness tests aligned by ignition time 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 105 

As shown in the temporal curves, there is a variability in the 14 in. (36 cm) pan curves, with ignition 

times ranging from 20 minutes to nearly an hour. This is also much longer than the tests conducted in 

the 8 in. (20 cm) pans, which had ignition times of approximately 7.5 minutes. Much higher levels of 

smoke and temperatures were measured long before ignition occurred for the larger pan tests. This 

also resulted in much lower slopes, with the pan and oil temperatures nearly reaching steady state 

before ignition occurred. The difference between the 7, 8, and 10 inch (18, 20, 25 cm) pans was less 

pronounced than for the 14 in. (36 cm) pans. In general, it appeared as though the 8 in. (20 cm) pan 

provided the fastest heating to ignition and shortest activation windows, likely due to the reduction in oil 

volume and pan mass compared to the 10 in. (25 cm) pan, and the increase in pan/element contact 

area compared to the smaller 7 in. (18 cm) pan. 

The calculated slopes in the pan and oil temperature curves, differences between the pan (center of 

pan) and oil (center of oil) temperatures at ignition, and the integrated smoke obscuration at fixed pan 

temperatures are shown in Table 17. The tests utilizing different brands of the same size and gauge 

pans have been combined in the table (e.g., the 10 inch pans referenced for pan size tests include both 

the Vollrath and Browne-Halco pans tested). The 14 in. (36 cm) pan tests have much lower pan and oil 

temperature slopes approaching ignition than the shorter tests conducted. The total integrated smoke 

concentration is also nearly 5 times that for other tests conducted. The difference between the pan and 

oil temperatures was the lowest for the 10 inch pan tests conducted, but that is mostly attributed to the 

use of more responsive thermocouples for oil measurement in Phase 2. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 17 – Calculated pan and oil temperature slopes and obscuration slope and integrated areas for pan size/t

Pan 

Average pan temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Average oil temp slope 

between fixed pan 

temperatures and 

ignition (°C/min) 

Difference between pan and oil 

temperature at fixed pan temps 

(°C) 

Integ

up to 

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

250°C

(482°F)

300°C

(572°F)

350°C

(662°F)

375°C

(707°F)

IGN

250°C

(482°F)

8 Gauge Aluminum Pans – Pan Diameter

7 inch 30 27 23 20 35 33 31 28 71 67 67 58 44 3 

8 inch 39 35 29 25 44 39 35 33 64 57 55 54 44 0 

10 inch 25 21 17 13 28 25 23 23 36 36 37 37 16 0 

14 inch 7 5 3 2 8 7 5 5 50 47 44 43 24 5 

10 inch pans – Pan Thickness 

10 gauge 26 23 18 15 31 28 25 24 42 40 37 37 17 0 

8 gauge 25 21 17 13 28 25 23 23 36 36 37 37 16 0 

8 inch pans – Pan Thickness 

10 gauge 32 29 23 20 40 35 31 29 98 87 83 82 57 4 

8 gauge 34 31 25 22 40 37 35 34 62 61 59 55 37 0 

5 gauge 31 28 24 21 33 28 28 24 52 41 47 42 38 0 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 107 

6.9.3. Smoke Production and Ignition Temperatures 

The pan and oil temperatures at the time smoke obscuration measured 1.6%/ft (5%/m) are shown in 

Figures 101 and 102, respectively. The pan temperatures were observed to decrease with an increase 

in pan size and with an increase in pan thickness. The oil temperatures were less affected, with the 

exception of low oil temperature measurements in the pork lard test included in the 8 gauge, 8 in. (20 cm) 

pan thickness analysis. 

Figure 101 – Average pan temperature at 1.6%/ft (5%/m) smoke measurement for various pan 

sizes (top) and thicknesses (bottom) 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 108 

Figure 102 – Average oil temperature at 1.6%/ft (5%/m) smoke measurement for various pan 

sizes (top) and thicknesses (bottom) 

The oil temperatures when the average pan temperature reached 300°C (572°F) are shown in 

Figure 103. The average pan temperatures measured for the 14 in. (36 cm) pan were reduced due to 

the pan thermocouples location outside the diameter of the element. Pan TC2 is located in the center of 

the element and pan, but pan TC1 and TC3 were located at the outer edges of the pan, outside the 

diameter of the element. These thermocouples, especially TC1, measured reduced temperatures (by 

as much as 70°C (126°F), as shown in Figure 104. This chart shows the temperatures measured at 

each pan location when the average of the three locations was 300°C (572°F). The center pan 

temperature was consistently higher than the outer measurements. The reduced outer pan 

temperatures result in reduced average pan temperatures. This causes an increase in the average oil 

temperature when fixed pan temperature threshold of 300°C (572°F) is reached, as shown in 

Figure 103. No similar relationship was observed relating to pan thickness. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 109
 

Figure 103 – Average oil temperature when pan = 300°C (572°F) for multiple oil depths 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 110 

Figure 104 – Pan temperatures measured across all spatial locations for a test with 14 in. 

(36 cm) pan 

The calculated correlations between the total heating time to ignition and the pan and oil temperatures 

at smoke measurement, and the oil temperatures at 300°C (572°F) pan measurement are shown in 

Figure 105. The correlations are strongly influences by the outlying points for the 14 in. (36 cm) pan, 

and much less discernable trends are observed when this point is neglected from the analysis. The pan 

temperature at smoke production and the oil temperature at the fixed pan temperature appear to be 

more asymptotic than linear. With longer and longer tests, the pan temperature at smoke will not get 

lower than approximately 290°C (554°F) and the oil temperature when the pan temperature reaches 

300°C (572°F) will not increase above 280°C (536°F). Both of these results would make physical 

sense, as the length of test cannot indefinitely continue to reduce/increase measured temperatures at 

fixed points. The oil temperature at smoke production varies by over 40°C (72°F) with almost no 

discernable relationship with the total heating time to ignition. No clear correlation can be drawn. 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 111 

Figure 105 – Correlations and slopes for total heating time and pan and oil temperatures at 

smoke production and oil temperatures at fixed pan temperature 

The pan and oil temperatures at the time of ignition are shown in Figures 106 and 107, respectively. 

The pan temperatures at ignition were observed to decrease slightly both with increasing pan size and 

with increasing pan thickness. The effect is most pronounced for the change from 10 in. (25 cm) to 14 in. 

(36 cm) pans, with the pan temperature at ignition decreasing by approximately 20°C (36°F). This is to 

be expected, as the larger pan extends farther off the element, reducing the overall average pan 

temperature. A similar but less dramatic effect can be observed for the thicker pans, with average 

temperatures at ignition decreasing by approximately 5°C (9°F) for increasing pan gauges. 

Oil temperatures did not trend with pan size or thickness as did the pan temperatures. No consistent 

trend was observed for the oil temperature at ignition due to either pan size or thickness. The average 

temperatures did vary by as much as 20°C (36°F), but the effect did not appear systematically related 

to the pan characteristics, but rather test variability. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 112 

Figure 106 – Average pan temperature at ignition for various pan sizes (top) and thicknesses 

(bottom) 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 113 

Figure 107 – Average oil temperature at ignition for various pan diameters (top) and pan 

thicknesses (bottom) 

6.10. Pan Warping and Temperature Overshoot 

Testing was conducted in Phase 1 to evaluate the ability to warp a pan using thermal cycling. A dry 10 

gauge, 8 in. (20 cm) diameter pan was heated on the 8 in. (20 cm) GE electric coil element until the pan 

temperature measured approximately 400–450°C (750–840°F). All power was then cutoff to the 

element and the temperature overshoot was measured. When the temperature began to decrease it 

was dunked into a large water tank to initiate rapid cooling. This process was repeated through 30 

heating and cooling cycles. Several of the heating cycles are shown with the measured range power 

output in Figure 108. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 114 

500 3000

450

2500

400

350

Pan Temperature (°C)

2000

300

250 1500

200

1000

150

100

500

50

0 0

0 500 1000 1500 2000 2500 3000 3500 4000

Test Time (sec)

Pan Temp Range Power

Range Power (W)

Figure 108 – Pan temperature and range power during rapid heating and cooling 

After 30 heating and cooling cycles were conducted, the pan flatness was measured about the center 

of the pan in a 2 in. (5.1 cm) radius. The maximum deviation measured across this area was 0.058 in. 

(1.5 mm) This is greater than the 0.006 times the diameter (8 x 0.006 = 0.048 in. (20 x 0.006 = 1.2 mm)) 

threshold specified in UL 1026 [4]. It is less than the maximum deviation of 0.25 in. (6.4 mm) reported 

by a UL 858 task group for Technical Feasibility and Performance Goals (TFPG) for implementation of 

a contact temperature sensing device for range fire prevention [5]. 

During each cycle, the power was cut to the range and the temperature of the pan allowed to continue 

rising due to residual thermal gradients between the element and pan surface. This effect is considered 

a temperature overshoot. A representative pan temperature overshoot is shown in Figure 109. 

HUGHES ASSOCIATES 
   

   

STANDARD COOKING FIRES 1DTG02049.009 PAGE 115 

0

500

1000

1500

2000

2500

3000

400

405

410

415

420

425

430

250 270 290 310 330 350 370 390

Range Power (W)

Pan Temperature (°C)

Test Time (sec)

Thermal Cycling Pan

Pan Temp Range Power

Power Off

Overshoot Temp

Figure 109 – Pan temperature overshoot when range power cycled off 

Temperature overshoots were generally observed to vary between 1–11°F (1–6°C) and occurred over 

3–10 seconds. The magnitude of the overshoot was typically increased with reduced pan temperatures. 

At lower pan temperatures, the residual temperature gradient between the element surface and the pan 

surface was increased, and the temperature overshoot would be greater in magnitude. The greatest 

overshoots were observed for pan shutoff temperatures of approximately 715°F (380°C). At lower pan 

cutoff temperatures, the overshoot may be further increased. 

7. GLOBAL TEST CORRELATIONS 

The preceding sections have compared the results of numerous tests by isolating variables. In order to 

focus the analysis within each section, only select tests were considered. Several trends were observed 

to occur in many test series. For example, the available time windows between the measurement of 

1.6%/ft (5%/m) smoke and ignition and between an average pan temperature of 300°C (572°F) and 

ignition were found to correlate well with the total heating time to ignition. In addition, the average pan 

and oil temperatures at ignition were often found to decrease with increasing total heating time to 

ignition. This section combines the analysis from all test variables and attempts to identify and quantify 

these global correlations observed across all tests. 

For most test scenarios conducted, the total heating time to ignition was found to correlate well with the 

variable conditions, such as element power, pan size and shape, pan mass and thermal properties, and 

oil depth and volume. The total heating time was also found to correlate well with the calculated 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 116 

minimum heating time to ignition (a linear combination of the pan and oil mass, specific heat capacity), 

temperature at ignition, and the total element power input. 

Other test metrics characterizing potential challenges to prevention devices, such as the time windows 

for pan temperature or smoke activation, pan and oil temperatures at smoke production and ignition, 

were either correlated to the total heating time to reach ignition or showed minimum response at all. 

The only other variable found to impact these metrics, was the % FFA of the oil used for testing. While 

this was not found to impact the ignition temperatures, oils with low % FFA were found to produce 

smoke at higher temperatures and provide a shorter potential window for activation by smoke detection 

technologies. 

For calculation of the global correlations, all Phase 2 tests have been included in the analysis. The 

Phase 1 tests were neglected due to the lack of repeated tests and the use of less responsive oil 

temperature measurements. The Phase 2 tests included evaluation of all the variables (without all the 

scenarios) included in Phase 1 and resulted in both the fastest and slowest ignition among all tests. A 

description of each test scenario (1–16) is provided in Table 2 in Section 5.3. The correlation of the 

heating time to reach ignition with the calculated minimum time to ignition (which combines most 

pan/element variables) is shown in Figure 110. The calculation of the minimum time to ignition is 

discussed in Section 5.4.6 and shown in Eq. (2). 

Figure 110 – Correlation between the measured time to ignition and the calculated minimum 

ignition time for all Phase 2 tests 

The minimum heating time to ignition is a calculated variable that incorporates a number of 

pan/element/oil factors. In order to further improve the calculated ignition time, a correction factor has 

been empirically developed to account for the difference in size between the pan (D) and the element 

(B). The correction factor was calculated using Eq. (3), for pan and element sizes in inches. 

ܨ ൌ ஻ା஺௕௦ሺ஻ିሺ஽ିଶ.ହሻሻ Eq. (3) ଶ.ଶହ

When the minimum ignition time is multiplied by the correction factor, the estimated ignition times are 

much closer to the actual ignition times, and the correlation is improved. This correlation is shown in 

Figure 111 along with a line of equality (calculation of the exact ignition time). The calculated times are 

slightly shorter than the actual times to ignition as shown by the curve falling above the line of equality. 

This is likely due to the influence of other variables such as the conductivity of the pan, the pan 

flatness, and the pan stability. However, cursory attempts to develop combined correlations 

incorporating these variables were not successful and are beyond the scope of this project. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 117 

Figure 111 – Correlation between the corrected measured time to ignition and the calculated 

ignition time for all Phase 2 tests 

The measured pan and oil temperatures at the time of ignition correlated negatively with the total 

heating time to reach ignition. Longer tests generally ignited with lower measured pan and oil 

temperatures. The actual curves appeared to be asymptotic, reaching minimum temperatures at the 

longest tests conducted. The pan and oil temperatures and estimated curve fits are shown in Figure 112. 

Pan temperatures were found to decrease by approximately 2.1°C (3.8°F) per minute of heating to 

ignition for times between 381 and 1095 seconds, with a strong correlation in this range of -0.85. The 

pan temperature stopped decreasing with increased test length and approached an asymptote at 

approximately 377°C (711°F). Oil temperatures also decreased with increasing heating time to ignition 

by approximately 0.9°C (1.6°F) per minute of heating time between 381 and 1095 seconds. The 

correlation is not as strong as the pan temperatures, with a moderate correlation of -0.48 measured. 

The oil temperature at ignition also asymptotes for longer tests, reaching an approximate minimum of 

370°C (697°F) for the longest tests conducted. The equations used to calculate the curve fits are based 

on the minimum and maximum times to ignition and pan and oil temperatures. They are shown in Eq. (4) 

and Eq. (5) for the pan and oil temperatures, respectively. The correlations were developed to 

investigate the averages from all the tests to try to understand the trend. In order to use the data for 

design of a minimum possible temperature should focus on the lower error bounds shown in the plots. 

Figure 112 – Correlation between the total heating time to ignition and the pan and oil 

temperatures measured at ignition 

ሾ426 െ 377ሿ ൅ 377 Eq. (4) ଷ െ 381ሻ൧ ܲܽ݊ ܶ݁݉݌ ܽݐ ܫ݃݊݅ݐ݅݋݊	ሺԨሻ ൌ ൣ1 െ atan	ሺݐ௡௚௜

HUGHES ASSOCIATES 
	 	 	 	

STANDARD COOKING FIRES 1DTG02049.009 PAGE 118 

ሾ400 െ 370ሿ ൅ 370 Eq. (5) ସ െ 381ሻ൧ ܱ݈݅ ܶ݁݉݌ ܽݐ ܫ݃݊݅ݐ݅݋݊	ሺԨሻ ൌ ൣ1 െ atanሺݐ௡௚௜

The time windows between a fixed pan temperature threshold (300°C (572°F) and ignition and between 

a smoke obscuration threshold (1.6%/ft (5%/m)) and ignition scaled proportionally with the total heating 

time to ignition across all tests conducted. These values are representative of potential activation 

windows for prevention devices measuring either pan temperatures or smoke concentrations. Shorter 

time windows indicate more challenging fires to prevent. Decreasing the total heating time reduces the 

available operating time for these devices. If the thresholds are shifted, the total available time can be 

increased or decreased, but remain proportional to the total ignition time. The correlations for the pan 

and temperature thresholds are shown in Figure 113. 

Figure 113 – Correlation between the total heating time to ignition and time windows for 

activation of fixed pan temperature or smoke obscuration thresholds 

In general, the challenge for detection for any device can be linked to the total heating time required to 

reach ignition. By decreasing the total test time, the available operating windows are shortened and the 

margin of safety between operation and ignition is reduced. The total test time can be reduced by: 

 Decreasing the volume of oil used for testing 

 Sizing the pan to match the element diameter 

o 8 in. (20 cm) pans heated fastest on 8 in. (20 cm) element 

o 8 in. (20 cm) pans ignited faster than either smaller or larger pans 

 Increasing the element power output 

 Using a flatter and more stable pan
 

 Using a pan with less mass and lower specific heat capacity
 

 Using a pan with greater conductivity 

Challenging scenarios are not only the fastest to reach ignition, however. Tests with slower heating 

times to ignition had lower measured pan and oil temperatures at ignition than fast tests and very flat 

temperature slopes. The average pan and oil temperatures decreased by approximately 2.1°C (3.8°F) 

and 0.9°C (1.6°F) per minute of additional heating time to reach ignition, respectively. Both pan and oil 

temperatures were found to reach asymptotes for the longest tests at approximately 377°C (711°F) and 

370°C (697°F), respectively. Depending on the technology, these reduced temperatures at ignition may 

present additional challenges to prevention devices. 

8. COMPARISON OF TEST INSTRUMENTATION 

A large number of instruments were used to measure the pan and oil temperatures, effluent 

temperatures, and smoke obscuration for these characterization tests. For creation of a test standard, 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 119 

the total number of devices can likely be reduced. In order to identify the best locations for 

instrumentation, the individual measurements from each test have been compared to the overall 

average values. The devices that best represent the average should be included in the standard tests, 

and all other instrumentation should be removed. 

The average differences between each measurement location and the average value over all tests 

conducted are shown in Table 18. The average temperature or smoke obscuration was calculated for 

each second during each test, and the difference between individual points was calculated and 

averaged throughout the duration of the test from heating to ignition. These average differences are 

shown in the table. As shown, there was almost no variation (<1°C, <1%/ft) between the smoke meters 

and the effluent thermocouples located in the hood. This shows that the effluent was uniform within the 

hood above the range. 

There is also almost no variation between the average oil temperature and the oil temperatures 

measured slightly above and below the half oil depth. Averaged over all tests, the temperature slightly 

above the half depth had zero difference, and the temperature slightly below was increased by 1°C 

(1.8°F), variation below the accuracy of the thermocouples used during testing. The variation in the oil 

temperatures was greater laterally than by depth. In general, either oil TC 1 and or oil TC 3 measured 

slightly higher or lower than the average by 3–5°C (5–9°F), and the center thermocouple generally 

tracked the average best. It is recommended for simplicity that a single center thermocouple placed at 

the half oil depth be used for subsequent oil temperature measurements. It should be inserted as close 

to the half oil depth as reasonable, but as long as it remains within the oil and does not touch the pan it 

should provide sufficient accuracy. 

Greater variability was observed for the pan temperature measurements. On average, pan TC1 

(located closest to the handle) measured the highest, and pan TC 3 (farthest from the handle) 

measured the lowest temperatures. This was true for all scenarios except for 3, 8, 9, 14, and 16. These 

tests all used different pans than the baseline tests, which used the Vollrath 10 in. (25 cm), 8 gauge 

aluminum pan. This pan was found to lean slightly towards the handle due to the torque applied by the 

handle mass and the slightly curved pan bottom. The pans used in Scenarios 3, 8, 9, 14, and 16 either 

settled at different angles, had convex shaped bases, or extended well beyond the base of the element 

compared to the baseline pan. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 

Table 18 – Average variation between individual measurements and test averages for comparison of inst

See Table 2 in 

Section 5.3 for 

description of 

test scenarios 

Pan 

Temperatures Oil Temperatures 

Effluent 

Temperatures 

Ob

Pan 

TC1 

Pan 

TC2 

Pan 

TC3 

Oil 

TC1 

Oil 

TC2 

Oil 

TC 3 

Above 

Half 

Oil 

Depth 

Below 

Half 

Oil 

Depth EF1 EF2 EF3 EF4 Meter 

(°C) (°C) (°C) (°C) (°C) (°C) (°C) (°C) (°C) (°C) (°C) (°C) (%/m

Scenario 1 11 1 -12 -6 3 3 0 0 1 0 0 -1 -1 

Scenario 2 9 1 -10 -6 2 4 0 0 0 0 0 0 0 

Scenario 3 5 -5 0 -4 3 1 0 0 0 0 0 1 0 

Scenario 4 12 1 -13 -5 2 4 0 0 0 1 0 0 -1 

Scenario 5 10 1 -11 -6 3 3 0 0 0 0 0 0 -1 

Scenario 6 10 1 -12 -4 3 1 0 0 0 0 0 0 1 

Scenario 7 7 -3 -4 -3 3 3 0 -3 0 0 0 0 0 

Scenario 8 6 -8 4 -3 1 2 0 0 0 0 0 0 -1 

Scenario 9 11 -16 5 -2 3 -1 0 -1 0 0 0 0 -1 

Scenario 10 5 -1 -4 -4 2 0 -1 2 0 0 0 0 -1 

Scenario 11 7 -3 -4 3 -4 8 -3 -5 -1 0 1 0 1 

Scenario 12 0 0 0 5 -2 4 -2 -5 0 0 0 0 1 

Scenario 13 10 2 -12 -4 1 2 0 0 0 0 0 1 0 

Scenario 14 5 -14 8 -5 0 5 1 0 0 0 0 0 -1 

Scenario 15 -1 0 1 -4 2 1 0 0 0 0 0 1 0 

Scenario 16 -31 27 4 -5 3 3 0 0 1 0 -1 0 -1 

All Phase 2 Tests 6 -2 -5 -3 2 3 0 -1 0 0 0 0 0 

All Phase 1 Tests 6 -1 -4 -5 3 -1 -1 3 0 0 0 0 -1 

All Tests 7 -2 -5 -4 2 1 0 1 0 0 0 0 -1 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 121 

For tests conducted with very large pans (Scenario 16), the center pan temperature was an average of 

27°C (49°F) greater than the test average. This was due to the reduced temperatures at location 1 and 

3 where the pan did not contact the element. It is believed that the center temperature is most 

representative of the actual pan temperatures in this case, despite its difference from the average. 

The other tests showing the largest disparity between the center temperature and the average were 

Scenario 9 (16°C (29°F) below average) and Scenario 14 (14°C (25°F) below average). Scenario 9 was 

conducted using the cast iron pan which had a slightly convex base, reducing contact between the 

center of the pan and the element, reducing the center pan temperature. Scenario 14 was conducted 

with the low end stainless steel pan, and it is unclear why the center temperature was reduced for this 

case. Considering all other test cases, however, the center pan temperature remained within 10°C 

(18°F) of the average pan temperature and provided a good estimate of the average. The center 

measurement should be sufficient for characterization of standard tests. 

9. RECOMMENDATIONS FOR TEST STANDARD 

One intent of a standard test is to provide a realistic test condition that bounds other likely hazardous 

conditions. Therefore, a device that can prevent the standardized scenario can reasonably be expected 

to prevent most other potential fire scenarios. The use of combustible cooking oils for testing was 

selected because it presents the greatest potential hazard, and should bound other cooking fire 

scenarios. This analysis was conducted in order to identify the cooking oil scenarios that would present 

the greatest challenge to potential prevention devices. In addition, recommendations are provided for 

demonstrating that an acceptable test has been run, and performance guidelines for evaluating 

prevention devices. 

9.1.1. Test Scenarios 

In order to determine the conditions presenting the greatest challenge, three potential types of detection 

devices have been considered. These theoretical devices, and the situations that cause them the 

greatest challenge, include: 

 Pan temperature measurement with fixed pan temperature threshold 

o Shortest time windows between fixed pan temperatures and ignition 

o Lowest pan temperatures at ignition
 

 Pan temperature measurements incorporating algorithm (e.g., rate-of-rise) 

o Smallest or largest slope of pan temperature approaching ignition 

o Shortest time window between fixed pan temperatures and ignition 

o Lowest pan temperatures at ignition
 

 Smoke concentration sensor 

o Shortest time window between production of smoke and ignition 

o Lowest total amount of smoke produced before ignition 

With regard to selection of an oil, canola oil was found to produce smoke at the highest temperatures 

(275–280°C (527–536°F) on average), and reach ignition in the same time and same temperatures (or 

slightly faster) as the other oils. These aspects would provide the greatest potential challenges, and 

therefore canola oil was selected for continued testing. Although only tested once, the peanut oil used 

in Phase 1 also heated quickly and produced smoke at high temperatures, comparable to the canola oil 

tested. However, canola oil is deemed more representative of products found in homes than peanut oil, 

and it was selected for continued testing. 

No systematic variations in ignition or smoke temperatures were observed between commercial and 

consumer grade oils, or between various brands of oils tested. Oil temperatures measured when smoke 

obscuration reached 1.6%/ft (5%/m) varied by as much as 30°C (54°F) for repeat tests conducted with 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 122 

different oil brands, and oil temperatures measured at ignition varied by as much as 10°C (18°C). 

However, these variations occurred randomly and could not be attributed to any particular oil brand, 

with each brand producing both above and below average results for various test scenarios. It should 

be sufficient to select the oil type and purchase wherever available. 

Tests having the fastest heating time to reach ignition also had the shortest time windows for smoke or 

pan temperature activation, the highest slopes approaching ignition, and the lowest amount of total 

smoke production. Conversely, tests having the longest total time to ignition had the lowest pan 

temperatures at ignition and lowest slopes in temperature rise. In order to properly challenge all 

devices, it is recommended to conduct one short and one long heating test for standardized evaluation. 

Among the scenarios tested, the fastest tests included the use of the low end stainless steel pan on the 

3000 W glass ceramic top range with 1⁄4 in. (6.4 mm) of oil. These tests reached ignition in an average 

of 381 seconds (371–395). Comparably, the use of the same pan on the 2600 W coil element cooktop 

reached ignition in an average of 385 seconds (375–406). These two test conditions represent the only 

tested condition with heating times of less than 7 minutes. When the threshold is extended to 8 

minutes, the cast iron pan on the glass ceramic top range with 1⁄4 in. (6.4 mm) of oil and the Phase 1 

fresh canola oil and peanut oil tests (with 8 in. (20 cm) pan on 2600 W coil) are included as well. 

The longest tests conducted involved the use of the 14 in. (36 cm) pan. Of the five tests conducted with 

this pan, four ignited in less than an hour of heating with times ranging from 1199 to 3488 seconds 

(20–58 minutes). These tests were highly variable in total ignition time and pan and oil heating rates. 

When tests between 15–20 minutes were considered, this included the use of the 10 in. (25 cm) 

aluminum pan on the glass ceramic top range with 1⁄4 in. (6.4 mm) of oil and on the electric coil range 

with 1⁄2 in. (12.8 mm) of oil. 

The “fast” tests reaching ignition in less than 8 minutes, the “slowest” tests taking longer than 20 

minutes, and the “slow” tests taking between 15–20 minutes to ignition are summarized in Table 19. 

The maximum and minimum pan and oil temperatures and smoke obscuration obtained from each 

ignition time group are shown in Figure 113. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 123 

Table 19 – Test scenarios found to provide fast, slow, and slowest ignition times 

Test ID Pan Oil Range Ignition Time 

Size 

In. 

(cm) Material 

Mass 

g (lb) Type 

Depth 

In. (mm) Type 

Power 

W sec min 

FAST 

P1-5 8 (20) Aluminum 622 

(1.4) Canola 0.25 (6.4) Coil 2600 464 7.7 

P1-6 475 7.9 

P1-7 8 (20) Aluminum 622 

(1.4) Peanut 0.25 (6.4) Coil 2600 465 7.8 

P2-16 

10 (25) Stainless 

Steel 

694 

(1.5) Canola 0.25 (6.4) Coil 2600 

406 6.8 

P2-17 375 6.3 

P2-18 383 6.4 

P2-28 

10 (25) Stainless 

Steel 

694 

(1.5) Canola 0.25 (6.4) Glass ceramic 3000 

379 6.3 

P2-29 371 6.2 

P2-30 395 6.6 

P2-31 

10 (25) Cast Iron 977 

(2.2) Canola 0.25 (6.4) Glass ceramic 3000 

437 7.3 

P2-32 452 7.5 

P2-33 458 7.6 

Slow 

P2-25 

10 (25) Aluminum 817 

(1.8) Canola 0.25 (6.4) Glass ceramic 30001 

1026 17.1 

P2-26 1137 19.0 

P2-27 1109 18.5 

P2-25a 1109 18.5 

P2-37 

10 (25) Aluminum 817 

(1.8) Canola 0.50 (12.8) Coil 2600 

986 16.4 

P2-38 974 16.2 

P2-39 974 16.2 

Slowest 

P1-27 

14 (36) Aluminum 

1717 

(3.8) 

Canola 

0.25 (6.4) Coil 2600 

1398 23.3 

P1-28 Soybean 1199 20.0 

P2-43 1808 

(4.0) Canola 

2230 37.2 

P2-44 3488 58.1 

P2-45 DNI2 

1 – Power was cycled on/off by glass break sensor, average power approximately 2000 W 

2 – DNI (did not ignite) after 1 hour of heating 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 124 

Figure 113 – Pan and oil temperatures and smoke obscuration curves for fastest and slowest 

ignition times among all tests 

HUGHES ASSOCIATES 
 

STANDARD COOKING FIRES 1DTG02049.009 PAGE 125 

The specific test conditions provided above and in Table 19 should be considered as guidelines for 

achieving fast and slow tests, but other combinations of variables will likely produce comparable test 

results. Many combinations of test variables (pan, range, oil) should be able to produce fast and slow 

tests. 

Due to the variability in the 14 in. (36 cm) pan tests, it may be desirable to run a “slow” (15–20 minute) 

test as the test standard, or find other means for lengthening the test duration while maintaining tighter 

repeatability, such as increasing the depth/volume of oil used. 

9.1.2. Demonstration of Acceptable Test 

Regardless of the test conditions used to achieve the desired ignition times, the standard tests should 

fall within the bounds of the pan and oil temperature and smoke profile curves shown above for each 

time grouping. If the device to be tested relies only on temperatures measured at the pan/oil/range 

level, there should be no need to construct the collection hood and measure smoke production from the 

test source. In addition, when constructing the hood it should not be necessary to instrument with 

temperature or gas measurements, as these measurements did not provide significant additional data 

regarding the approach to ignition. 

As discussed in Section 8.0, the pan and oil temperatures need only be measured at the center of the 

pan and the center depth of the oil. The oil temperature should remain below the oil surface and not 

contact the base of the pan, but slight variations in depth from the half oil depth (e.g., ± 1/16 inch for 1⁄4 

inch oil depth) should not significantly impact the measurements. 

While the characterization tests were all run to ignition, this should not be necessary for demonstration 

of an acceptable test in standardized testing. All tests that were run in Phase 2 (most responsive TC 

measurements) ignited at center oil temperatures greater than or equal to 350°C (7662 °F), with the 

lowest center oil temperature measured at 374 °C (795 °F) for the aluminum pan on the glass ceramic top 

range. 

The shortest time window between the time the center oil temperature reached 350°C (662°F) and 

ignition was 29 seconds, for the canola oil tested in the cast iron pan on the 3000 W glass ceramic top 

range. If standardized scenarios are run until the center oil temperature reaches 350°C (662°C), it 

should be possible to demonstrate sufficient alignment with the previous tests without having to deal 

with the increased hazards resulting from ignition. 

If the element is shut off at the time the oil temperature reaches this threshold, the test data can then be 

aligned using this point as time zero. The measured maximum and minimum pan and oil temperatures, 

and smoke obscuration for the fast, slow, and slowest tests conducted are shown in Figure 114. 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 126 

Figure 114 – Pan and oil temperatures and smoke obscuration bounds aligned to a measured oil 

temperature of 350°C (662°F) 

HUGHES ASSOCIATES 
STANDARD COOKING FIRES 1DTG02049.009 PAGE 127 

There is some overlap in curves between the slow and slowest tests. The desired standard test could 

select between these two types of tests, or require both. Both time boundaries would provide a 

moderate scenario between the extremes for additional prevention confidence. 

If a prevention device cannot be disabled or isolated from the range during testing, it may be possible 

that an oil temperature of 350°C (662°F) cannot be reached to verify test acceptability. If this is the 

case, a test should be run until the prevention device activates. The pan and oil temperature and 

smoke (if applicable) curves should then be plotted with the start of heating aligned within the bounds of 

the initial times for the fast, slow, or slowest tests shown above. The same alignment time must be 

provided to all curves uniformly, and different start times should not be applied to demonstrate 

acceptable pan, oil, or smoke curves separately. If the growth profiles can be contained within the 

bounds of the curves up until the prevention device activates, this should be sufficient demonstration of 

an applicable test. Baseline tests should be repeated in triplicate to demonstrate alignment with the 

desired test boundaries. 

If smoke is not used as a prevention criteria by the device under test, there is no reason to measure 

smoke during testing and demonstrate consistency with the above smoke test criteria. If smoke is to be 

used as an activation criteria, it must be demonstrated that the test setup produces smoke within the 

boundaries shown above using the same 4 ft x 4 ft (1.2 x 1.2 m) enclosed collection hood. If this can be 

verified, the hood should then be removed and the same range/pan/oil should be tested within a mock 

kitchen with operable exhaust hood. The design of this kitchen space, the configuration and flow rates 

of the exhaust hood, the installation location of the proposed sensor, and the expected smoke 

obscuration profiles have not been defined. Additional effort will be required before these aspects of a 

test standard can be defined. 

9.1.3. Prevention Device Performance Criteria 

After an acceptable test setup has been demonstrated, the prevention device should be installed and 

activated and the exact test condition repeated. If the device has not activated by the time the oil 

temperature reached 350 °C (662°F), or allows the oil to reach this threshold after activation, the test 

should be manually ended and the device considered unacceptable. This maximum threshold 

temperature has been selected because no ignitions occurred prior to this threshold in the tests 

conducted. If desired, a lower maximum threshold could be selected. In this case, the demonstration of 

an acceptable test could also be shifted to provide better alignment with the desired threshold. 

Useful data for selection of an oil temperature threshold is provided in Table 20. In addition to the 

tested data, potential thresholds are provided from a Japanese gas range standard [6,7], a series of 

cooktop temperature limited tests conducted by Primaira [8], and an existing temperature limited device 

[9]. As shown, the oil temperature threshold of 350 °C (662 °F) would provide a minimum of 29 

seconds before ignition for the tests conducted with corresponding pan temperatures ranging from 365­

407 °C (689-765 °F). For the phase 2 tests utilizing the final recommended instrumentation, ignitions 

did not occur until the oil temperatures reached 374-406 °C (705-763 °F) and pan temperatures 

reached 385-432 °C (725–810 °F). Based on the available test data a threshold in the range of 300 to 

350 °C (572 to 662 °F) should be sufficient for prevention of ignition. If a more conservative threshold 

is desired, such as 250 °C (482 °F) oil temperature, the minimum time to ignition increases to 130 

seconds and the resulting pan surface temperatures decrease to 263-312 °C (505-594 °F). An oil 

temperature threshold of 300 °C is currently used by the Japanese Industrial Standard (JIS) 2103 and 

2093 [6,7]. 

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STANDARD COOKING FIRES 1DTG02049.009 PAGE 128 

Table 20 – Data for selection of oil temperature maximum threshold 

Temperature at Ignition (Center TC Only)

Location

Min

[°C (°F)]

Max

[°C (°F)]

Pan 385 (725) – Test P2‐18 432 (810) Test P2‐26

Oil 374 (705) ‐ Test P2‐25a 406 (763) ‐ Test P2‐32

Oil Temperature

Threshold

(Center TC only)

Minimum

Remaining Time

To Ignition

Pan Temperature

Range

(Center TC only)

[sec] [Test]

Min

[°C (°F)]

Max

[°C (°F)]

250 °C (482 °F) 130 P2 ‐ 28 263 (505) 312 (594)

300 °C (572 °F) 85 P2 ‐ 29 316 (601) 360 (680)

325 °C (617 °F) 60 P2 ‐ 31 342 (648) 388 (730)

350 °C (662 °F) 29 P2 ‐32 365 (689) 407 (765)

Representative Existing Temperature Criteria for Prevention Devices

Japanese Standard JIS 2103, 2093 [6,7]

Limit oil temperature to 300 °C (572 °F) on gas range

Primaira Cooktop Temperature Control Study [8]

Limited temperature of pan bottom to 371°C (700°F)

Safe‐T‐ElementTM Temperature Limiting Device [9]

Limit temperature of cast iron plate to 350 °C (662 °F)

Pan and oil temperatures would also remain below this threshold

In order to simplify the analysis, no other criteria beyond the oil temperature threshold should be 

included for verification of an acceptable mitigation device test result. Additional limits should not be 

imposed on the pan temperature or smoke concentration. If the device can prevent the measured oil 

temperature from exceeding this threshold, it should be considered sufficient prevention performance. 

A minimum pan temperature threshold should also be applied to prevent against potential nuisance 

activations and ensure the device allows for realistic cooking to be performed. Based on a previous 

assessment of cooking practices, some high temperature cooking operations may require pan bottom 

temperatures of 246–289°C (475–550°F) and food temperatures from 232–260°C (450–500°F) [10]. A 

minimum activation temperature threshold in this range should also be considered for evaluation of 

prevention devices. For example, a fire prevention technology should not limit an oil temperature below 

250°C (482°F). 

In addition to a minimum temperature threshold, it should be demonstrated that the inclusion of the 

prevention device does not alter the heating rate from the baseline tests. The pan and oil temperature 

growth curves obtained with the device installed should not deviate from the test conducted without the 

device up until the prevention device has activated (within some defined bounds of error). 

For example, for a fast heating test conducted without a prevention device and average pan 

temperature slope of 54°C/min (97°F/min) may be observed. This would be within the bounds of an 

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STANDARD COOKING FIRES 1DTG02049.009	 PAGE 129 

acceptable test as shown in Figure 114 in Section 9.1.2. A prevention device is then installed and found 

to activate when the pan temperature equals 350°C (662°F), but the pan temperature slope is 

decreased to 20°C/min (36°F/min). This may not be considered an acceptable test result, even though 

the device prevented ignition within the minimum and maximum pan temperature limits. This device 

could drastically increase the time required to cook food. Limits should be placed (e.g., 10%) on the 

reduction in heating rate of the pan/oil compared to the base line testing. 

If a device can: 1) operate after the desired minimum oil temperature is reached; 2) operate before the 

maximum oil temperature is reached; and, 3) does not drastically reduce the heating rate measured 

without the device present, it should be considered acceptable. These three criteria would be required 

for achieving a passing test result. 

9.1.4. Summary of Recommendations 

Based on the characterization tests conducted, the following requirements for conduct of a 

standardized test are recommended. 

 Instrumentation 

o	 Single welded 24 gauge, type K thermocouple welded to the center of the top surface of 

the test pan 

o	 Single Inconel sheathed, grounded bead, type K 0.010 in. (0.25 mm) thermocouple 

inserted into the oil at half the oil depth near the center of the pan 

o	 632 mm red 5 mW laser mounted in a 4 ft x 4 ft (1.2 x 1.2 m) collection hood centered 

over the test pan at a height of 3 ft (0.9 m) above the range with photodiode sensor 

 Only necessary if prevention device under test (DUT) utilizes smoke 

measurements for activation 

 Entire collection hood only needed if fire prevention system utilizes smoke 

 Test Setup 

o	 Any combination of range/pan/oil that can reach ignition: 

 In less than 8 minutes 

 In greater than 20 minutes (15–20 may be considered instead) 

o	 Must demonstrate pan and oil temperatures within the bounds developed (see 

Figure 114) up to a pan temperature of 375°C (572°F) 

 Need not run test to ignition to verify acceptable test condition 

 Must conform with smoke bounds only if fire prevention system utilizes smoke for 

activation 

 If prevention device cannot be disabled or removed from range, pan/oil/smoke 

curves must align up to the activation point of the device 

 Recommend using conditions already tested, but if the applicability of a certain 

prevention technology limits the selection of ranges or pans, other conditions 

may be demonstrated acceptable 

 Device Performance 

o Device must not activate before a predetermined oil temperature has been reached 

 For example, 250°C (482°F) based on potential oil temperatures for high 

temperature cooking 

 Some cooking may be performed with food temperatures as high as 260°C 

(500°F) [10] 

o Device must not activate after a predetermined oil temperature has been reached 

 Should prevent temperature, even with overshoot after cutting power from range 

 300 to 350°C (572 to 662°F) may be appropriate 

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STANDARD COOKING FIRES 1DTG02049.009	 PAGE 130 

 This range is based on the results of the characterization tests. No test ignited 

within 29 seconds of reaching 350 °C 

 An existing Japanese pan temperature limiting device specifies a maximum of oil 

temperature of 300°C (572°F), rather than a minimum [6,7] 

 Primaira cooktop temperature limiting study use a pan bottom temperature of 

371°C (700°F) without an ignition occurring [8] 

 Safe-T-ElementTM limits the plate surface to 350 °C (707 °F), oil temperature 

therefore also limited below this threshold [9] 

o	 Device must not reduce the pan or oil heating rate from the baseline test by greater than 

specified threshold 

 This number should be selected to limit the impact of prevention devices on 

cooking performance and heating rates 

 For example, 10%, but a greater or smaller acceptable margin may be 

considered 

10. REFERENCES 

1. Ahrens, M., “Home Fires Involving Cooking Equipment,” National Fire Protection Association, 

Quincy, MA, November 2012. 

2. Dinaburg, J. and Gottuk, D.T. “Home Cooking Fire Mitigation: Technology Assessment – Final 

Report,” prepared for The Fire Protection Research Foundation, Quincy, MA, HAI Project 

#1DTG02049.006, October 31, 2011. 

3. Bockisch, M., “Fats and Oils Handbook,” AOCS Press, Champaign, IL, 1993, p. 96. 

4. Underwriters Laboratory, Inc. “UL 1026, Electrical Household Cooking and Food Serving 

Appliances, Section 41.2.9.1,” 2012. 

5. Underwriters Laboratory Inc., “UL 858-04-01, Technical Feasibility Performance Goals,” 2002. 

6. Japanese Industrial Standard (JIS) 2103, Gas Burning Cooking Appliances for Domestic Use, 

1991. 

7. Japanese Industrial Standard (JIS) 2093, Test Methods of Gas Burning Appliances for Domestic 

Use, 1991. 

8. “Pan Temperature-Limiting Control Technology to Reduce Incidence of Unattended Cooking 

Fires,” prepared for the U.S. Consumer Product Safety Commission by Primaira, LLC, Woburn, 

MA, 2011. 

9.	 Pioneering Technology, Inc. “Safe-T-Element: Product Brochure.” 

10. “Technical, Practical and Manufacturing Feasibility of Technologies to Address Surface Cooking 

Fires,” Arthur D. Little, Inc., May 2001. 

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