performance of current smoke alarms to the additional test requirements of ansi ul 217 ......

Performance of Current Smoke

Alarms to the Additional Test

Requirements of ANSI UL 217-

2015

Thomas Cleary

National Institute of Standards and Technology

Gaithersburg, MD

Consumer Product Safety Commission

Bethesda, MD

February 15, 2017

Acknowledgement

This work is a collaborative research project

with funding support from the U.S. Consumer

Product Safety Commission.

Arthur Lee is the technical point of contact.

Acknowledging Michael Selepak, Laurean

DeLauter, Anthony Chakalis, Mariusz

Zarzecki, Amy Mensch, and Maylin Odenthal

for smoke box and test room fabrication, and

assisting with the data collection.

Outline

• Objectives

• Background

• Experimental Details

• Results

• Analysis

• Conclusions

Objectives

The objectives of this research were to assess:

1. whether the new performance tests in ANSI/UL

217-2015 Standard for Safety of Smoke Alarms

will foster a demonstrable enhancement in

smoke alarm performance compared to a wide

range of currently available smoke alarms

2. whether the single nuisance source test in the

Standard is representative of a range of

cooking nuisance scenarios

Background

• The issuance of ANSI/UL 217-2015 Standard for Smoke Alarms (8th Ed.) has introduced requirements in the form of new flaming and smoldering polyurethane foam tests, and a new cooking nuisance test.

• During the extensive development of the new test requirements, limited information was gathered on the performance of existing smoke alarms to the new proposed tests.

• The timeframe between now and the roll out of new smoke alarms meeting this Standard (after the Standard’s effective date) provides an opportunity to examine performance of currently available smoke alarms.

Research Leading to the Addition of

Tests to ANSI/UL 217-2105• NIST- Dunes II smoke alarm research (2001-2002)

• FPRF/UL - Smoke Characterization Project (2007)

• UL – STP task groups and research at UL on new tests (2008-2015)

• NFPA - 72 task group reports

– Minimum Performance Requirements for Smoke Alarm Detection

Technology (2008)

– Task Group on Smoke Detection Follow-up Report (2009)

• CPSC - Pilot Study of Nuisance Alarms Associated with Cooking (2010)

• NIST/CPSC - Smoke Alarm Performance in Kitchen Fires and Nuisance

Alarm Scenarios (2013)

• NIST - Improving Smoke Alarm Performance – Justification for New

Smoldering and Flaming Test Performance Criteria (2014)

• FPRF - Smoke Alarm Nuisance Source Characterization: Experimental

Results conducted by Jensen Hughes (2015)

NIST Smoke Alarm Sensitivity Study

(2008)The fire tests were conducted in a building mock-up designed to

represent a portion of an apartment or small home

Fire Fire

BedroomLiving

Room

Kitchen

15.8 m

4.9 m

x x

xx c

cc

S5S6

S4 S3

S2 S1

hf

DoorLaser

ExtinctionLaser

Extinction

Laser

Extinction

X - thermocouple tree location

hf - total heat flux gage (1.5 m above the floor and pointing toward the fire)

S1…S6 - alarm set location

c - gas sampling location (1.5 m above the floor)

dashed line - beam path for extinction measurements (1.5 m above the floor)

Smoke alarms were mounted four across on

panel boards in random order

P1 photoelectric

I1 Ionization

D1 dual alarm

D2 dual alarm

Analyzing the Data

ASET/RSET Concepts

• Available Safe Egress Time - ASET is the time to reach a threshold

tenability limit on either combustion gas exposure, thermal

exposure, or smoke concentration

• Required Safe Egress Time – RSET is the time it takes for

occupants to egress. It depends on pre-movement activities, travel

distance and speed

Installed smoke alarms should provide early

enough warning such that ASET > RSET

Master

Bedroom

(MBR)Living Room

(LR)

Kitchen

Bedroom

(BR)

Door(closed)

Door(open or closed)

Exit

3.7 m

8.9 m

3.0 m

4.0 m

ChairMock-up

ChairMock-up

4.0 m

Analysis of Full-scale Experiments to

Aid Selection of New Fire Test Criteria

• Estimate proposed alarm activation times and

corresponding ceiling smoke obscurations for

flaming and smoldering fire scenarios subject to

ASET and RSET assumptions for a desired

performance metric.

• Relate the ceiling smoke obscurations for

flaming and smoldering scenarios to the

performance criteria for the flaming and

smoldering polyurethane foam test fires.

Matched pairs of flaming and smoldering fire performance criteria

where the average success rate is nominally equal for smoke

obscuration target values on the same row

Flaming fire test alarm criterion

Smoldering fire test alarm criterion

Smoke Obscuration(%/ft obsc.)

Averaged success rate and standard deviation (%/%)

Smoke Obscuration(%/ft obsc.)

Averaged success rate and standard deviation (%/%)

2* 94.3/5.7 12* 93.0/4.4

4 86.0/11.4 14 86.0/11.6

5 79.0/14.1 16 80.8/16.5

6 71.8/17.0 20 69.0/19.7

8 59.8/19.1 22 58.8/20.0

10** 49.0/19.1 24** 45.3/21.7

*Matched performance achievable with combination photoelectric/Ionization alarm

**Current standalone photoelectric and ionization alarms would most likely pass with these criteria

NIST/CPSC Cooking Nuisance Tests

• Cooking scenarios consisted of: – broiling a hamburger

– broiling frozen pizza

– frying a hamburger

– making a grilled-cheese sandwich in a no-stick frying pan

– stir-frying vegetables in a wok on the electric burner

– frying bacon

– toasting bread

• Light, medium, and dark toast

– toasting frozen bagels


8.6 m

4.4 m

Alarm activation frequency for equal fractions

of range top, oven and toasting activities

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5 6 7

P1 I1 D1 D2 M1 M2

Ala

rm A

cti

va

tio

n F

req

uen

cy

Distance from Cooking Source (m)

New Test Descriptions

• Smoldering Flexible Polyurethane Foam

– Heated foam block to induce smoldering

– Passing criterion – must alarm before 12 %/ft obscuration

• Flaming Flexible Polyurethane Foam

– Flaming ignition of a foam block

– Passing criterion – must alarm before 5 %/ft obscuration

• Broiled Hamburgers

– Electric range oven, frozen hamburgers 75/25 blend

– Passing criterion – No alarm before 1.5 %/ft obscuration

Experimental Details

• Experimental sources

– Flaming foam

– Smoldering foam

– Broiled hamburgers

– Lightly toasting bread

– Frying a hamburger

– Stir-frying vegetables

• The cooking experiments produce mean particle

sizes from ~ 0.1mm to over 1 mm


• 45 Alarm Models from 8 Manufacturers

– 14 Ionization

– 14 Photoelectric

– 7 Ionization/Carbon Monoxide

– 4 Photoelectric/Carbon Monoxide

– 4 Combination Ionization/Photoelectric

– 2 Photoelectric/Thermal

• Six units for every model, each smoke alarm

checked in the smoke box with cotton wick

smoke


NIST constructed a smoke box per ANSI-UL

217 specifications. All smoke alarms tested

in the smoke box before room experiments.


80

85

90

95

100

30405060708090100

Be

am

Lig

ht

Tra

ns

mis

sio

n (

%)

Measuring Ionization Chamber (MIC) Current (pA)

Typical smoke box smoke profiles

Beam light transmission

versus time

Beam light transmission versus MIC

reference chamber

Thick solid lines are bounding curves from the Standard

Experimental DetailsNIST constructed a test room per ANSI-UL 217specifications

for the new test experiments and additional cooking sources

Experimental LayoutUL 217 test room in the NIST National Fire Research Laboratory

36 ft.

22 ft.

17.7 ft.

MIC

Obsc.

Fire

36 ft.

22 ft.

10 ft.

MIC

Obsc.

Electric

Range

Wall

Fire Tests Cooking Tests


• The 45 smoke alarm models distributed to 15

test boards with three different alarms on each

board

• Each fire and cooking experiment conducted

three times for each set of nine alarms

• Nine smoke alarms (three test boards) per

experiment, 15 (5x3) experiments per source

• The three test boards changed position for each

repeated experiment

Smoke Sources

Flaming Source: Flame ignition of foam slab

Smoke Sources

Smoldering Source:

Radiant heating of foam slab

Smoldering Source:

Cigarette ignition w/ or w/o radiant

heating

Smoke Sources

Radiant heating Cigarette ignition Radiant heating

w/ cigarette ignition

Sequence chosen

for testing

Cooking Nuisance Source

75 % lean beef and 25 % suet by

weight, 10 cm diameter

Two frozen patties on broiler

pan

Pan placed on top rack close to

broiling element

Broiler on high, door open

Other Cooking Experiments

Two-slice toaster placed on

range top

Toasted bread after experiment

Stir-fried vegetables

Fried hamburger

Measurements

• Time to Alarm

• Light Obscuration

• MIC (reference ionization chamber)

• Temperature, Relative Humidity

• CO, CO2, HCN

• Particle Size Distribution

• Light Scattering

Smoke Box Results

Ionization alarm I09

0

1

2

3

4

30

40

50

60

70

80

90

100

1 2 3 4 5 6

Be

am

Ob

sc

ura

tio

n (

%/f

t)

MIC

(p

A)

Alarm Unit Number

Average MIC Results

Ionization alarm models

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Av

era

ge

MIC

Cu

rren

t (p

A)

Ionization Alarm Model

Smoke Box Results

Photoelectric alarm P01

0

1

2

3

4

30

40

50

60

70

80

90

100

1 2 3 4 5 6

Be

am

Ob

sc

ura

tio

n (

%/f

t)

MIC

(p

A)

Alarm Unit Number

Average Beam Obsc. Results

Photoelectric alarm models

0

0.5

1

1.5

2

2.5

3

3.5

4

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Ave

rag

e B

ea

m O

bs

cu

rati

on

(%

/ft)

Photoelectric Alarm Model

Range of Smoke Box Results for

All Alarm Types

Allowable range for alarm

response

• MIC reference chamber

– 93 pA to 37.5 pA

• Smoke Obscuration

– 0.5 %/ft to 4.0 %/ft

Range of average results

for various alarm types

• Ionization

– 87 pA to 53 pA

• Ionization/CO and /photolectric

– 74 pA to 64 pA

• Photoelectric

– 1.8 %/ft to 3.3 %/ft

• Photoelectric/CO and /thermal

– 1.1 %/ft to 3.9 %/ft

Flaming Foam Results


versus MIC current


versus time

40

50

60

70

80

90

100

0 100 200 300 400 500 600

Be

am

Lig

ht

Tra

ns

mis

sio

n (

%)

Time (s)

40

50

60

70

80

90

100

0102030405060708090100B

ea

m L

igh

t T

ran

sm

iss

ion

(%

)

Measuring Ionization Chamber (MIC) current (pA)


Smoldering Foam ResultsThree trial smoldering initiation sequences

40

50

60

70

80

90

100

2000 2500 3000 3500 4000

Radiant HeaterCigarette Radiant Heater and Cigarette

Be

am

Lig

ht

Tra

ns

mis

sio

n (

%)

Time (s)


versus MIC current0

20

40

60

80

100

0102030405060708090100

Radiant HeaterCigaretteRadiant Heater and Cigarette

Be

am

Lig

ht

Tra

ns

mis

sio

n (

%)

Measuring Ionization Chamber (MIC) current (pA)


versus time


Smoldering Foam Results

40

50

60

70

80

90

100

2000 2200 2400 2600 2800 3000

Be

am

Lig

ht

Tra

ns

mis

sio

n (

%)

Time (s)

0

20

40

60

80

100

0102030405060708090100B

ea

m L

igh

t T

ran

sm

iss

ion

(%

)

Measuring Ionization Chamber (MIC) Current (pA)


versus time


versus MIC current


Radiant heater and cigarette initiation sequence

Broiling Hamburgers Results

0

0.5

1

1.5

2

2.5

3

0 500 1000 1500

Ob

sc

ura

tio

n (

%/f

t)

Time (s)

0

0.5

1

1.5

2

2.5

3

3.5

4

30405060708090100O

bs

cu

rati

on

(%

/ft)

MIC Current (pA)


versus time


versus MIC current


Frying Hamburger Results

0

0.5

1

1.5

2

2.5

3

0 500 1000 1500

Ob

sc

ura

tio

n (

%/f

t)

Time (s)

0

0.5

1

1.5

2

2.5

3

3.5

4

30405060708090100

Ob

sc

ura

tio

n (

%/f

t)

MIC Current (pA)


versus MIC currentBeam light transmission

versus time

Thick solid lines are bounding curves for broiling

hamburgers from the Standard

Stir-frying Vegetables Results

0

0.5

1

1.5

2

2.5

3

0 500 1000 1500

Ob

sc

ura

tio

n (

%/f

t)

Time (s)

0

0.5

1

1.5

2

2.5

3

3.5

4

30405060708090100O

bs

cu

rati

on

(%

/ft)

MIC Current (pA)


versus MIC current



Toasting Bread Results

0

10

20

30

40

50

60

70

80

90

100

0 300 600 900 1200 1500

MIC

Cu

rre

nt

(pA

)

Time (s)

Beam light transmission versus time



Flaming and Smoldering Source

Ionization Alarm Results

Flaming Source Tests

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Bea

m O

bs

cu

rati

on

at

Ala

rm (

%/f

t)


Pass

0

5

10

15

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Bea

m O

bs

cu

rati

on

at

Ala

rm (

%/f

t)


Estimated Pass

Smoldering Source Tests

Open symbol - Alarm

Closed symbol - Test maximum, no alarm

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Bea

m O

bs

cu

rati

on

at

Ala

rm (

%/f

t)


Pass

Broiling and Frying Hamburgers

Source Ionization Alarm Results

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Bea

m O

bs

cu

rati

on

at

Ala

rm (

%/f

t)


Broiling Source Tests Frying Source Tests

Open symbol - Alarm


Stir-frying and Toasting Source

Ionization Alarm Results

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Beam

Ob

scu

rati

on

at

Ala

rm (

%/f

t)


60

70

80

90

1 2 3 4 5 6 7 8 9 10 11 12 13 14

MIC

Cu

rren

t a

t A

larm

(p

A)

Ionization Alarm ModelOpen symbol - Alarm


Stir-frying Source Tests Toasting Source Tests

Flaming and Smoldering Source

Photoelectric Alarm Results

Flaming Source Tests

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Bea

m O

bs

cu

rati

on

at

Ala

rm (

%/f

t)


Pass

0

5

10

15

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Bea

m O

bs

cu

rati

on

at

Ala

rm (

%/f

t)


Pass

Smoldering Source Tests

Open symbol - Alarm


0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Bea

m O

bs

cu

rati

on

at

Ala

rm (

%/f

t)


Pass

Broiling and Frying Hamburgers

Source Photoelectric Alarm Results

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Beam

Ob

scru

ati

on

(%

/ft)


Broiling Source Tests Frying Source Tests

Open symbol - Alarm


Stir-frying Source Photoelectric

Alarm Results

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Beam

Ob

scu

rati

on

at

Ala

rm (

%/f

t)


Stir-frying Source Tests

Open symbol - Alarm


Performance Ranking Scheme

• Specify threshold limits that correspond to the Standard (M),

somewhat less (L) and more (H) restrictive threshold limits.

– Flaming foam limits: L=7 %/ft, M=5%/ft and H=3%/ft

– Smoldering foam limits*: L=16%/ft, M=12%/ft and H=8%ft

– Cooking nuisance limits: L=1%/ft, M=1.5%/ft and H=2%/ft

• Tabulate how many times out of the three repeated tests an alarm

responsed within the specified limit

• Tabulate the number of three out of three successes for flaming,

smoldering and cooking tests to give a particular alarm model’s

ranking.

• A rank of 3 at the threshold limits corresponding to the Standard (M)

suggests the particular alarm model would pass the new Standard.

* Corresponding limits for ionization alarms: L=68 pA, M=75 pA and H=81 pA

Performance Ranking of

Photoelectric Alarms

Model Smoldering fire

tests meeting limit

Flaming fire

tests meeting limit

Broiling hamburgers

tests meeting limit

Performance rank

L M H L M H L M H L M H

P01 3 3 3 0 0 0 3 3 0 2 2 1

P02 3 3 3 3 1 0 0 0 0 2 1 1

P03 3 3 3 3 0 0 0 0 0 2 1 1

P04 3 3 3 2 0 0 0 0 0 1 1 1

P05 3 3 3 3 0 0 3 0 0 3 1 1

P06 3 3 3 3 1 0 0 0 0 2 1 1

P07 3 3 3 1 0 0 3 3 3 2 2 2

P08 3 3 3 3 0 0 2 1 1 3 1 1

P09 3 3 3 3 1 0 3 0 0 3 1 1

P10 3 3 3 3 1 1 0 0 0 2 1 1

P11 3 3 3 2 0 0 3 0 0 2 1 1

P12 3 3 3 3 0 0 0 0 0 2 1 1

P13 0 0 0 0 0 0 0 0 0 0 0 0

P14 3 3 3 1 0 0 3 3 0 2 2 1


Photoelectric/CO and /thermal Alarms


tests meeting limit

Flaming fire

tests meeting limit

Broiling hamburgers

tests meeting limit

Performance rank


PCO01 3 3 3 1 1 1 2 0 0 1 1 1

PCO02 3 3 3 0 0 0 0 0 0 1 1 1

PCO03 3 3 2 0 0 0 0 0 0 1 1 0

PCO04 3 3 3 1 1 1 2 0 0 1 1 1

PCO05 3 3 3 3 2 0 1 0 0 2 1 1

PCO06 3 3 3 3 1 0 0 0 0 2 1 1

PCO07 3 3 3 0 0 0 3 3 0 2 2 1

PT01 3 3 3 0 0 0 3 1 0 2 1 1

PT02 3 3 3 2 0 0 1 1 0 2 1 1


Ionization Alarms


tests meeting limit

Flaming fire

tests meeting limit

Broiling hamburgers

tests meeting limit

Performance rank


I01 0 0 0 3 3 3 3 0 0 2 1 1

I02 2 0 0 3 3 3 0 0 0 1 1 1

I03 3 3 0 3 3 3 0 0 0 2 2 1

I04 3 3 3 3 3 3 0 0 0 2 2 2

I05 3 3 1 3 3 3 0 0 0 2 2 1

I06 3 1 1 3 3 3 0 0 0 2 1 1

I07 2 0 0 3 3 3 0 0 0 1 1 1

I08 3 1 0 3 3 3 0 0 0 2 1 1

I09 3 0 0 3 3 3 0 0 0 2 1 1

I10 3 0 0 3 3 3 0 0 0 2 1 1

I11 0 0 0 3 3 3 0 0 0 1 1 1

I12 0 0 0 3 3 2 0 0 0 1 1 0

I13 0 0 0 3 3 1 3 1 0 2 1 0

I14 0 0 0 3 3 2 3 1 0 2 1 0

Performance Ranking of Ionization/CO

and Photoelectric Alarms


tests meeting limit

Flaming fire

tests meeting limit

Broiling hamburgers

tests meeting limit

Performance rank


ICO01 1 0 0 3 3 3 0 0 0 1 1 1

ICO02 2 0 0 3 3 0 3 3 1 2 2 0

ICO03 3 0 0 3 3 3 0 0 0 2 1 1

ICO04 2 0 0 3 3 3 0 0 0 1 1 1

IP01 3 3 3 3 3 3 0 0 0 2 2 2

IP02 3 3 3 3 2 2 0 0 0 2 1 1

IP03 3 3 3 3 3 3 0 0 0 2 2 2

IP04 3 3 3 3 3 3 0 0 0 2 2 2

Average Performance RankingThe average ranks of alarms containing a photoelectric sensor but

not an ionization sensor (and not considering P13) are 1.9, 1.1 and

0.9 for sensitivity levels of L, M and H respectively.

For alarms containing an ionization sensor but not a photoelectric

sensor the average ranks are 1.7, 1.2 and 0.8 for sensitivity levels of

L, M and H respectively.

A rank of 3 is required at the performance level M to meet the

performance level in ANSI/UL 217-2015. Thus, it is concluded that

smoke alarms meeting the performance criteria in ANSI/UL 217-2015

would demonstrate significantly improved overall performance by

expanding range of fire scenarios alarms must respond to while

requiring greater resistance to nuisance alarms than a wide range of

currently available models.

Comparison of Smoke Development

for Cooking Nuisance Sources

0

0.5

1

1.5

2

2.5

3

0 300 600 900 1200 1500 1800

Broiling hamburger

Frying hamburger

Stir frying vegetables

Ce

ilin

g S

mo

ke O

bsc

ura

tio

n (

%/f

t)

Time (s)

60

65

70

75

80

85

90

95

100

0 300 600 900 1200 1500 1800

Broiling hamburger

Frying hamburger

Stir frying vegetables

Toasting bread

MIC

Cu

rre

nt

(pA

)

Time (s)

Cooking Nuisance Source Analysis

The broiling hamburgers test produces an aerosol that

causes majority of alarm models studied to respond at low

enough levels that could be characterized as a nuisance,

and it appears to be a conservative test in that respect.

However, the observed differences in the cooking aerosol

production rates and aerosol properties appear to affect the

alarm response for photoelectric and ionization alarms for

the cooking activities examined.

Conclusions

• 1. Analysis of the results show that no current smoke

alarm model would meet the performance level required

in ANSI/UL 217-2015. Of the smoke alarms tested, three

models, all photoelectric sensor alarms, came closest to

meeting the new requirements.

• 2. An across the board increase in the level of

performance to that specified in ANSI/UL 217-2015

would significantly improve the overall performance of

smoke alarms by expanding range of fire scenarios

alarms must respond to while requiring resistance to

nuisance alarms.

Conclusions

• 3. The changes in ANSI/UL 217-2015, which include

the new performance fire tests and the new nuisance

resistance test, may make it challenging for

manufacturers to meet the requirements by simply using

a combination of photoelectric and ionization sensors, or

designing alarms that perform as well against the new

fire tests as the combination ionization / photoelectric

models examined.

• 4. The cooking aerosol production rates and beam /

MIC relationship between the sources varied significantly

and appeared to have an impact on the alarm response.

Conclusions

• 5. Toasting bread produced essentially no measurable

obscuration, carbon monoxide nor significant heat, thus

alarms that use sensors to detect these characteristics

will most likely not alarm during normal toasting

scenarios. The toasting bread aerosols produced

particles that caused the ionization alarms to responded,

which was similar to the measuring ionization chamber

(MIC) current levels in the broiling hamburgers

experiments.

Conclusions

• 6. The broiling hamburgers nuisance test challenged

the majority of smoke alarms included in this study, and

therefore may be considered a conservative test.

Ultimately, cooking nuisance experiments on a range of

smoke alarms that pass ANSI/UL 217-2015 will confirm

the appropriateness of the broiling hamburgers cooking

nuisance scenario as the model test.

performance of current smoke alarms to the additional test requirements of ansi ul 217 ......

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