Discussion of CPSC staff activities related to gas appliance safety, CO hazards, and CO/combustion sensor evaluation

1. This presentation has been prepared by CPSC staff. It has not been reviewed or approved
by, and may not necessarily reflect the views of, the Commission.
June 3, 2014
1

2. Purpose:
To help CPSC staff gain a broader
understanding of the scope, state of the art,
and availability of current or prototype sensor
technologies being used to shut off gas
heating appliances when incomplete
combustion or dangerous levels of CO are
detected or that are used in similar, harsh
environments.
2

3. Panel Session I:
 Project Overview: Purpose, Hazard Patterns, and
Annual CO Death Estimates
 Physiology of Carbon Monoxide Poisoning
 CPSC Staff’s CO-related Activities
 International Standards
3

4. Ronald Jordan, Mechanical Engineer,
Project Manager, Gas Appliance CO Sensor Project,
CPSC Directorate for Engineering Sciences
This presentation has been prepared by CPSC staff. It has not been reviewed or approved
by, and may not necessarily reflect the views of, the Commission.
4

5.  Purpose: To investigate the use of CO and
combustion sensors to reduce the occurrence
of unintentional CO deaths and injuries
caused by failure modes and mechanisms
associated with gas appliances
 Scope: gas furnaces, boilers, wall and floor
furnaces
5

6. Comparison of Annual CO Deaths Associated with Gas Furnaces, Boilers, & Wall/Floor Furnaces and Gas
Room/Space and Portable Gas Heaters
2001-2010
2001-
2010
Consumer Product
Average
Annual
Estimate
Average
Percent 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Total
Total (all consumer products1) 166.6 100% 121 181 153 168 190 180 186 178 148 161 1666
Gas Furnace (incl. Boilers, Wall/Floor
Furnaces) 29.6 18% 33 46 28 41 11 30 33 26 18 30 296
Gas Room/Space Heaters (incl.
Portable Gas Heaters) 18.8 11% 20 25 24 22 20 11 18 13 15 20 188
1. These deaths are non-fire related and are associated consumer products under CPSC jurisdiction.
Source: Hnatov, Matthew, Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products, 2010 Annual Estimates, U.S. Consumer Product
Safety Commission, Bethesda, MD January 2014.
Note: Table includes data for natural gas, LP-gas, and unspecified gas appliances
6

7. Leakage path for combustion products into
living space:
 Blocked flue or chimney
 Disconnected vent
 Depressurization of a small room
Coupled with incomplete combustion:
 Inadequate combustion air (i.e., too little air)
 Over-firing (i.e., too much fuel)
 Quenching of flame (i.e., flame temperature
too low)
7

8. Sandra Inkster, Ph.D., Physiologist/Pharmacologist,
CPSC Directorate for Health Sciences
This presentation has been prepared by CPSC staff. It has not been reviewed or approved
by, and may not necessarily reflect the views of, the Commission.
8

9.  Chemical asphyxiant gas: interferes with the body’s
oxygen (O2) supply
 CO binds to hemoglobin (oxygen carrying protein in
blood) >200-250x more readily than O2 and forms
carboxyhemoglobin (COHb)
 Level of O2 deprivation increases as COHb levels
increase
 Brain, heart, and exercising muscle have highest O2
demands so are most sensitive to CO poisoning effects.
9

10. Approximate Correlation Between Acute % COHb Levels and Symptoms
in Healthy Adults
% COHb Symptoms
<10% No perceptible ill effects*
10-20% Mild headache, labored breathing, decreased exercise
tolerance
20-30% Throbbing headache, mild nausea
30-40%
Severe headache, dizziness, nausea, vomiting, cognitive
impairment
40-50% Confusion, unconsciousness, coma, possible death
50-70% Coma, brain damage, seizures, death
>70% Typically fatal
*Some studies report adverse effects in cardiac patients at 2-5% COHb
(source: reviewed in Burton, 1996 )

11. Environmental
 Maximum level of CO attained in inhaled air; parts per
million (ppm)
 Rate of increase in CO levels
 Duration of CO elevation/CO exposure
Physiological
 Breathing rate of exposed individual; influenced by
activity level (Respiratory Minute Volume (RMV) = air
intake in liters/minute)
 General health status of exposed individual.
11

12. 0
10
20
30
40
50
60
70
80
0 4 8 12 16 20 24
%COHbLevel
Exposure Time (hours)
Effects of CO Level, Exposure Time, and Activity Level on
Carboxyhemoglobin (%COHb) Formation
1000 ppm CO
400 ppm CO
100 ppm CO
For each CO exposure level, the line style denotes indoor activity level represented by RMV;
dashed = sleeping (6L/min); solid = moderate level (15 L/min); dotted = high (normally short-lived bursts)
12

13.  Binding of CO to hemoglobin is reversible
 CO is removed from the body via exhaled air; the
elimination process is much slower than uptake
 The CO half-life means time needed to reduce %
COHb level by 50%
◦ ~4-5 hours at fresh ambient air (~21% oxygen)
◦ ~ 80 minutes with 100% normobaric oxygen
◦ ~20-30 minutes at 100% hyperbaric oxygen (HBO)
13

14.  Individuals With Certain Medical Conditions
◦ Cardiac diseases– especially ischemic heart disease/coronary
artery disease; also arrhythmias and congestive heart disease
◦ Chronic obstructive pulmonary disease (COPD)
◦ Anemias
 Infants and Young Children
◦ Have higher rate of CO uptake due to higher metabolic rate
 The Elderly
◦ Reflects high incidence of pre-existing diseased states above
 Fetuses
◦ Fetal hemoglobin has higher affinity for CO than maternal Hb and
will eventually attain 10-15% higher % COHb at equilibrium
14

15.  Variable: from complete recovery to brain-damaged,
vegetative state, depending on CO exposure, victim’s health.
 Delayed neurological sequelae (DNS) can occur few days to
few weeks after apparent recovery from initial CO exposure –
hard to predict, more likely at higher CO exposures resulting in >20%
COHb; does not necessarily require loss of consciousness (LOC).
 Obvious effects: e.g., paralysis, dementia, blindness, hearing
loss, Parkinson-like muscle/gait disorders.
 Subtle effects: e.g., emotional instability, memory loss,
inability to concentrate - often overlooked, but negatively affects
work and home life so can have economic, social, and personal impact
on victims and their families.
15

16. Ronald Jordan, Mechanical Engineer,
Project Manager, Gas Appliance CO Sensor Project,
CPSC Directorate for Engineering Sciences
This presentation has been prepared by CPSC staff. It has not been reviewed or approved
by, and may not necessarily reflect the views of, the Commission.
16

17.  Participation in voluntary standards
development and advocacy for CO alarm
usage
 Annual CO Safety Press Release
 Product recalls
 Participation in voluntary standards
development for gas appliances
17

18.  The following changes were made to the
voluntary standards in the mid to late-1980’s
to address CO risks:
◦ Vent Safety Shutoff System (VSSS) added to protect
against blocked & disconnected vents in vented
space heaters (ANSI Z21.11.1)
◦ Oxygen Depletion Safety (ODS) shutoff system
added to protect against CO production in unvented
space heaters (ANSI Z21.11.2)
18

19.  The following changes were made to the
voluntary standards in the mid to late-1980’s
to address CO risks:
◦ Blocked Vent Safety Shutoff (BVSS) added to protect
against blocked vents in gas furnaces (ANSI Z21.47)
◦ Blower door interlock switch added to prevent
combustion products from being pulled from heat
exchanger and circulated throughout house via
ducts (ANSI Z21.47).
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20. CO Death Estimates “Before” and “After” changes to Voluntary Standards
(as a percent of all consumer product related fatalities)
*Note: In earlier years CPSC’s annual estimates did not include distinctions between gas room/space heaters and portable heaters, therefore the
estimates for gas space heaters during the period from 1982 to 1990 may also include portable gas heaters as well.
Source: 1982-1990 data: “Non-Fire Incident Related Carbon Monoxide (CO) Deaths Estimates for 1990,” Long, Kimberly, U.S. Consumer Product
Safety Commission, Bethesda, MD April 1994
Source: 1999-2007 data: Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products. 2007 annual Estimates,” Hnatov,
Matthew, U.S. Consumer Product Safety Commission, Bethesda, MD January 2011
22%
41%
16%
14%
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
Gas Furnaces Gas Space Heaters
CODeathsassociatedwithgasfurnacesand
spaceheaters,includingPortableGasHeaters
(asapercentofallConsumerProducts)
9-Year period of estimate
1982-1990 (Before) 1999-2007 (After)
20

21. Total Estimated CO Fatalities “Before” and “After” changes to Voluntary Standards
*Note: In earlier years CPSC’s annual estimates did not include distinctions between gas room/space heaters and portable gas heaters, therefore the
estimates for gas space heaters during the period from 1982 to 1990 may also include portable gas heaters as well.
Source: 1982-1990 data: “Non-Fire Incident Related Carbon Monoxide (CO) Deaths Estimates for 1990,” Long, Kimberly, U.S. Consumer Product Safety
Commission, Bethesda, MD April 1994
Source: 1999-2007 data: Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products. 2007 Annual Estimates,” Hnatov, Matthew,
U.S. Consumer Product Safety Commission, Bethesda, MD January 2011
535
1024
230
199
0
200
400
600
800
1000
1200
1 2
TotalAnnualCODeathsAssociatedwithGasFurnaces
andSpaceHeatersandPortableGasHeaters
9-Year period of estimate
1982-1990 (Before) 1999-2007 (After)
Gas Furnaces Gas Space Heaters
21

22. Made to ANSI Z21.47 Central Furnace
Subcommittee (2001) and ANSI Z21/83
Technical Committee (2002):
◦ Require a means to prevent furnace CO emissions
from exceeding 400 ppm; or
◦ Require a means to shut down furnace if CO
emissions exceed 400 ppm.
22

23.  CO shutoff testing with catalytic bead and
mixed metal oxide semiconductor (MMOS) CO
sensors integrated into the vent pipe of a gas
furnace (2001)
 CO shutoff testing with electrochemical CO
and infrared CO2 sensors integrated into the
vent pipe of a gas furnace (2004)
23

24.  Formed the ANSI Z21/83 Ad Hoc Working Group
(AHWG) for CO/Combustion Sensors to evaluate
feasibility of sensors for use in all vented gas
heating appliances (2002)
 AHWG developed a test criterion for sensors
(2004)
 ANSI Z21/83 Technical Committee opted to not
pursue sensor evaluation (2005) due to concerns
that commercially available sensors:
◦ Were not durable enough to operate in gas appliance
flue.
◦ Did not have lifespan of a gas appliance (15-20 years).
24

25.  Durability and longevity testing of catalytic
bead CO and infrared CO2 sensors integrated
into the vent pipe, flue passages, and heat
exchanger of a gas furnace (2007-2008)
25

26. Standards
Development
Organization (SDO)
Standard Requirement
Japanese Standards
Association (JSA)
JIS S 2109,
Gas burning water
heaters for domestic
use
Shutdown appliance at ambient CO
level = 300 ppm (based on the CO
concentration in the combustion
gas)
European
Committee for
Standardization
(CEN)
EN 16430,
Combustion product
sensing devices for
gas burners and gas
burning appliances
Use of combustion product sensing
devices (CPSD) within the flue of gas
appliances to ensure combustion
efficiency
26

27. Panel Session II:
Industry Presentations
27