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Facility boilers: Are you at risk?
FEATURE
Facility boilers: Are you at risk?
By Richard C. Stone
R
ecent events at the University of Nevada, Reno (UNR) illustrate the importance of ensuring proper installation and function of boilers to prevent introduction of contaminants into facility air handling systems. Of specific concern during these events was occupant exposure to carbon monoxide which is undetectable by sight, smell, or taste and is the leading cause of death due to poisoning in the United States1,2. Historically, carbon monoxide has been implicated in the deaths of tennis player Vitas Gerulaitis and Edgar Allen Poe.
BACKGROUND AND EVENT HISTORY
The UNR campus chemistry building services nearly 1000 undergraduates each week with approximately 80 graduate students, faculty, and staff. Two gas-fired boilers service this facility with additional steam provided by a central heat plant during winter months. In 1993, a forced-draft gas burner boiler was installed in an interior basement mechanical room to provide summer laboratory steam. A roof-level atmospheric penthouse boiler (Figure 1) was installed in 1995 to provide hot water for make-up air units located on the roof. At approximately 11:00 P.M. on November 4, 1996, a battery-operated
Richard C. Stone, CIH, CSP is an industrial hygienist at the Environmental Health & Safety Department, University of Nevada, Reno, NV 89557 (e-mail: rstone@ unv.edu). 30
carbon monoxide detector recently installed by a researcher to monitor laboratory experiments alarmed in a basement laboratory. Upon arrival,
During maintenance requiring shutdown of building makeup air, combustion gases from the basement mechanical room were drawn into the negatively pressurized basement hallway where they were recirculated in the building HVAC system without benefit of dilution by outside air. the Reno Fire Department discovered building carbon monoxide concentrations approaching 1000 ppm. After building evacuation it was determined that atmospheric conditions had caused penthouse boiler combustion gases to be pulled into the penthouse where they were subsequently drawn into the adjacent facility HVAC air
© Division of Chemical Health and Safety of the American Chemical Society Published by Elsevier Science Inc.
handler. Fortunately, in large part due to the forward thinking of a researcher, no injuries or loss of life occurred. As a result of this incident a solid-state carbon monoxide detector with local and remote alarms was installed in the penthouse boiler room. Detector relays were used to enable shut down of both the boiler and facility air handler when penthouse carbon monoxide concentrations exceeded 50 ppm. Despite these efforts another incident occurred in 1998. During maintenance requiring shutdown of building make-up air, combustion gases from the basement mechanical room were drawn into the negatively pressurized basement hallway where they were recirculated in the building HVAC system without benefit of dilution by outside air. Air measurements taken by the Reno Fire Department indicated rapidly rising carbon monoxide concentrations in excess of 230 ppm throughout the building. It was not clearly determined whether combustion gases were drawn from the penthouse to the basement mechanical room through a connecting pipechase or if the combustion gases originated from the basement mechanical room boiler itself. This incident prompted installation of a similar solid-state detection and alarm system in the basement boiler room. Additional commercially available AIM SAS 6-96D locally alarmed self-powered electrochemical carbon monoxide detectors with digital display were placed in hallways of each floor. Notifier LCD-80 annunciators with audible and visible warnings were installed at each building entrance and tied to a new Notifier AFP 400 building fire alarm control panel.
1074-9098/01/$20.00 PII S1074-9098(00)00208-2
these incidents, several individuals experienced headache and nausea. One workers compensation claim related to carbon monoxide exposure was also filed.
LESSONS LEARNED
Figure 1. Penthouse Atmosphere GasFired Boiler.
Yet a third incident occurred in 1999 while maintenance personnel were on an unrelated assignment in the penthouse boiler room. After noticing boiler rollout, these individuals took quick action to shut down the boiler, limiting penthouse carbon monoxide concentrations to 225 ppm and preventing further building contamination. Given several false alarms and questionable relay operation, both penthouse and basement boiler carbon monoxide gas detectors were replaced with Vulcain VA-201T digital readout electrochemical detectors. Detector relays were interfaced with the fire alarm control panel, enabling boiler shutdown and remote monitoring at both facility annunciators and the central heat plant. This also enabled the fire alarm control panel to provide evacuation voice messages in the event of gas detection alarms and allowed emergency responders to provide specific instruction to building occupants. Corrective action ultimately culminated in removal of the penthouse boiler from service and installation of a heat exchanger (Figure 2) to provide rooftop make-up air unit hot water from the basement boiler. Although no serious or lasting health consequences occurred during
All but the third incident occurred after hours in a student-occupied building. This demonstrates the importance of implementing building specific emergency plans that include occupant training. Fortunately, UNR chemistry building occupants followed appropriate procedures in notifying a response agency and evacuating the building. Contractor installation of non-specific solid-state detectors resulted in numerous false alarms, potentially compromising occupant response to genuine emergencies. If contaminant detection is warranted, specific electrochemical detectors should be installed and placed on a maintenance schedule that includes routine calibration. Contractors should notify facilities personnel before welding or cutting in monitored equipment rooms so that building alarms can be silenced and to enable remote or local assessment of contaminant concentrations. This can be accomplished through contractual safe work plans or a hot work permit program. If remote or lo-
Significant resources were dedicated to the installation of detection devices and alarm systems which, after much research and some trial and error, performed admirably. cal monitoring of contaminant levels is not possible, it may be necessary to perform hot work off-shift during lowoccupancy periods. Notification and instruction should be provided to building occupants who may be present during these activities. Buildings containing laboratory hoods tend to pull outside contaminants through door openings, windows, and other building penetrations. Contaminant alarms are easily triggered by adjacent idling vehicles or portable generators used by contractors to power equipment. Unnecessary openings should be sealed
Figure 2. Basement Heat Exchanger.
Chemical Health & Safety, March/April 2001
31
whenever possible and contaminant sources minimized through access restrictions such as sign postings near doorways and intakes. Care must also be taken to provide proper air balance that ensures positive building pressure at these openings while maintaining negative pressure within laboratories. Significant resources were dedicated to the installation of detection devices and alarm systems which, after much research and some trial and error, performed admirably. Early resource allocation to eliminate hazard sources would have resulted in more timely resolution of this issue. Both occupant exposure and significant expense might have been avoided if the penthouse boiler had been originally installed in a manner to prevent exhaust gas entrainment in the facility HVAC system. Competent safety and health professional involvement at the design stage is critical before construction and renovation activities. Leased spaces should also be inspected for potential concerns. When it is time for contract renewal, make sure lease agreements contain appropriate language to protect the health interests of building occupants. Perhaps most importantly these
32
events emphasize the value of working cooperatively with facilities and maintenance personnel to identify problems and solutions. After these incidents a complete campus walkthrough of facility equipment and mechanical rooms was conducted with knowledgeable maintenance staff to determine other areas of potential hazard. Specific design features considered during each facility walkthrough included: ● ● ● ●
boiler/equipment rooms with access to adjacent HVAC systems boiler/equipment rooms with access to adjacent occupied areas boilers without appropriate gas shutdown interlocks boiler exhaust in close proximity to building air intakes.
Although no additional imminent hazards were discovered, several areas of concern were identified and prioritized for improvement. SUMMARY
Costs involved in addressing this issue were substantial. Carbon monoxide detection equipment exceeded $3,000, not including installation or calibration. Building alarm modifications, fire panel upgrades, and annunciation
approached $11,000, whereas an additional $70,000 was required to abandon the penthouse boiler and install a heat exchanger in its place. These expenses are justified when consequences of exposure to occupants and maintenance personnel are considered. At high concentrations, carbon monoxide can result in significant acute effects including coma and death. Acute exposure can also lead to chronic effects such as memory loss, personality changes, peripheral neuropathy, and speech disturbance.3,4 Lost time, workers compensation expenses, and potential litigation associated with exposure further validate the need for effective and timely solutions to these issues. References 1. Cobb, N.; Etzel, R. Unintentional carbon monoxide related deaths in the United States. JAMA, 1991, 266, 659. 2. National Center for Health Statistics. Vital statistics of the United States, 1990, Mortality Part A, 1994, DHHS no. PHS 95-1101 (Abstract). 3. Myers, R.; Snyder, S. K.; Emhoff, T. A. Subacute sequelae of carbon monoxide poisoning. Ann Emerg Med., 1985, 14, 1163. 4. Choi, I.S . Delayed neurologic sequelae of carbon monoxide toxicity. Arch. Neurol., 1983, 40, 433.
Chemical Health & Safety, March/April 2001
Facility boilers: Are you at risk?
By Richard C. Stone
R
ecent events at the University of Nevada, Reno (UNR) illustrate the importance of ensuring proper installation and function of boilers to prevent introduction of contaminants into facility air handling systems. Of specific concern during these events was occupant exposure to carbon monoxide which is undetectable by sight, smell, or taste and is the leading cause of death due to poisoning in the United States1,2. Historically, carbon monoxide has been implicated in the deaths of tennis player Vitas Gerulaitis and Edgar Allen Poe.
BACKGROUND AND EVENT HISTORY
The UNR campus chemistry building services nearly 1000 undergraduates each week with approximately 80 graduate students, faculty, and staff. Two gas-fired boilers service this facility with additional steam provided by a central heat plant during winter months. In 1993, a forced-draft gas burner boiler was installed in an interior basement mechanical room to provide summer laboratory steam. A roof-level atmospheric penthouse boiler (Figure 1) was installed in 1995 to provide hot water for make-up air units located on the roof. At approximately 11:00 P.M. on November 4, 1996, a battery-operated
Richard C. Stone, CIH, CSP is an industrial hygienist at the Environmental Health & Safety Department, University of Nevada, Reno, NV 89557 (e-mail: rstone@ unv.edu). 30
carbon monoxide detector recently installed by a researcher to monitor laboratory experiments alarmed in a basement laboratory. Upon arrival,
During maintenance requiring shutdown of building makeup air, combustion gases from the basement mechanical room were drawn into the negatively pressurized basement hallway where they were recirculated in the building HVAC system without benefit of dilution by outside air. the Reno Fire Department discovered building carbon monoxide concentrations approaching 1000 ppm. After building evacuation it was determined that atmospheric conditions had caused penthouse boiler combustion gases to be pulled into the penthouse where they were subsequently drawn into the adjacent facility HVAC air
© Division of Chemical Health and Safety of the American Chemical Society Published by Elsevier Science Inc.
handler. Fortunately, in large part due to the forward thinking of a researcher, no injuries or loss of life occurred. As a result of this incident a solid-state carbon monoxide detector with local and remote alarms was installed in the penthouse boiler room. Detector relays were used to enable shut down of both the boiler and facility air handler when penthouse carbon monoxide concentrations exceeded 50 ppm. Despite these efforts another incident occurred in 1998. During maintenance requiring shutdown of building make-up air, combustion gases from the basement mechanical room were drawn into the negatively pressurized basement hallway where they were recirculated in the building HVAC system without benefit of dilution by outside air. Air measurements taken by the Reno Fire Department indicated rapidly rising carbon monoxide concentrations in excess of 230 ppm throughout the building. It was not clearly determined whether combustion gases were drawn from the penthouse to the basement mechanical room through a connecting pipechase or if the combustion gases originated from the basement mechanical room boiler itself. This incident prompted installation of a similar solid-state detection and alarm system in the basement boiler room. Additional commercially available AIM SAS 6-96D locally alarmed self-powered electrochemical carbon monoxide detectors with digital display were placed in hallways of each floor. Notifier LCD-80 annunciators with audible and visible warnings were installed at each building entrance and tied to a new Notifier AFP 400 building fire alarm control panel.
1074-9098/01/$20.00 PII S1074-9098(00)00208-2
these incidents, several individuals experienced headache and nausea. One workers compensation claim related to carbon monoxide exposure was also filed.
LESSONS LEARNED
Figure 1. Penthouse Atmosphere GasFired Boiler.
Yet a third incident occurred in 1999 while maintenance personnel were on an unrelated assignment in the penthouse boiler room. After noticing boiler rollout, these individuals took quick action to shut down the boiler, limiting penthouse carbon monoxide concentrations to 225 ppm and preventing further building contamination. Given several false alarms and questionable relay operation, both penthouse and basement boiler carbon monoxide gas detectors were replaced with Vulcain VA-201T digital readout electrochemical detectors. Detector relays were interfaced with the fire alarm control panel, enabling boiler shutdown and remote monitoring at both facility annunciators and the central heat plant. This also enabled the fire alarm control panel to provide evacuation voice messages in the event of gas detection alarms and allowed emergency responders to provide specific instruction to building occupants. Corrective action ultimately culminated in removal of the penthouse boiler from service and installation of a heat exchanger (Figure 2) to provide rooftop make-up air unit hot water from the basement boiler. Although no serious or lasting health consequences occurred during
All but the third incident occurred after hours in a student-occupied building. This demonstrates the importance of implementing building specific emergency plans that include occupant training. Fortunately, UNR chemistry building occupants followed appropriate procedures in notifying a response agency and evacuating the building. Contractor installation of non-specific solid-state detectors resulted in numerous false alarms, potentially compromising occupant response to genuine emergencies. If contaminant detection is warranted, specific electrochemical detectors should be installed and placed on a maintenance schedule that includes routine calibration. Contractors should notify facilities personnel before welding or cutting in monitored equipment rooms so that building alarms can be silenced and to enable remote or local assessment of contaminant concentrations. This can be accomplished through contractual safe work plans or a hot work permit program. If remote or lo-
Significant resources were dedicated to the installation of detection devices and alarm systems which, after much research and some trial and error, performed admirably. cal monitoring of contaminant levels is not possible, it may be necessary to perform hot work off-shift during lowoccupancy periods. Notification and instruction should be provided to building occupants who may be present during these activities. Buildings containing laboratory hoods tend to pull outside contaminants through door openings, windows, and other building penetrations. Contaminant alarms are easily triggered by adjacent idling vehicles or portable generators used by contractors to power equipment. Unnecessary openings should be sealed
Figure 2. Basement Heat Exchanger.
Chemical Health & Safety, March/April 2001
31
whenever possible and contaminant sources minimized through access restrictions such as sign postings near doorways and intakes. Care must also be taken to provide proper air balance that ensures positive building pressure at these openings while maintaining negative pressure within laboratories. Significant resources were dedicated to the installation of detection devices and alarm systems which, after much research and some trial and error, performed admirably. Early resource allocation to eliminate hazard sources would have resulted in more timely resolution of this issue. Both occupant exposure and significant expense might have been avoided if the penthouse boiler had been originally installed in a manner to prevent exhaust gas entrainment in the facility HVAC system. Competent safety and health professional involvement at the design stage is critical before construction and renovation activities. Leased spaces should also be inspected for potential concerns. When it is time for contract renewal, make sure lease agreements contain appropriate language to protect the health interests of building occupants. Perhaps most importantly these
32
events emphasize the value of working cooperatively with facilities and maintenance personnel to identify problems and solutions. After these incidents a complete campus walkthrough of facility equipment and mechanical rooms was conducted with knowledgeable maintenance staff to determine other areas of potential hazard. Specific design features considered during each facility walkthrough included: ● ● ● ●
boiler/equipment rooms with access to adjacent HVAC systems boiler/equipment rooms with access to adjacent occupied areas boilers without appropriate gas shutdown interlocks boiler exhaust in close proximity to building air intakes.
Although no additional imminent hazards were discovered, several areas of concern were identified and prioritized for improvement. SUMMARY
Costs involved in addressing this issue were substantial. Carbon monoxide detection equipment exceeded $3,000, not including installation or calibration. Building alarm modifications, fire panel upgrades, and annunciation
approached $11,000, whereas an additional $70,000 was required to abandon the penthouse boiler and install a heat exchanger in its place. These expenses are justified when consequences of exposure to occupants and maintenance personnel are considered. At high concentrations, carbon monoxide can result in significant acute effects including coma and death. Acute exposure can also lead to chronic effects such as memory loss, personality changes, peripheral neuropathy, and speech disturbance.3,4 Lost time, workers compensation expenses, and potential litigation associated with exposure further validate the need for effective and timely solutions to these issues. References 1. Cobb, N.; Etzel, R. Unintentional carbon monoxide related deaths in the United States. JAMA, 1991, 266, 659. 2. National Center for Health Statistics. Vital statistics of the United States, 1990, Mortality Part A, 1994, DHHS no. PHS 95-1101 (Abstract). 3. Myers, R.; Snyder, S. K.; Emhoff, T. A. Subacute sequelae of carbon monoxide poisoning. Ann Emerg Med., 1985, 14, 1163. 4. Choi, I.S . Delayed neurologic sequelae of carbon monoxide toxicity. Arch. Neurol., 1983, 40, 433.
Chemical Health & Safety, March/April 2001