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

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

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  • 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). 19
  • 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

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