Topic: Building & Life Safety

Wind turbine

Wind turbines as confined spaces

Typically we think of climbing down into tanks, vaults or manholes for confined space entries.  Most would not think of wind turbines as having confined spaces.  Large enough to enter and perform work, restricted means of entry or egress and not designed for continuous human occupancy…. Wind turbines clearly have components that meet the definition of a confined space AND they have potential hazards.  With the push towards green energy, wind turbine installations are increasing rapidly.  In 2012 wind energy became the number one new energy source, with over 45,000 wind turbine installations currently in the U.S., according to AWEA (American Wind Energy Association).   Photos: While green technology may be good for the environment, it is not without hazards to the workers who install and maintain the technology.   As OSHA indicates on their Green Job Hazards webpage, “Green jobs are not necessarily safe jobs”. Hazards for workers in wind turbines include falls, electrical, mechanical, fire, and confined space hazards. Both OSHA and AWEA have pointed out the need for confined space training of wind turbine workers.   Confined spaces exist during construction and after installation of the turbines.  There are four main components that may be considered confined spaces; the tower (vertical support), the nacelle (the housing that contains the electrical components) the hub (hub attaches to nacelle) and the blades (attach to hub).  During construction of the turbine workers may need to enter sections of the tower, nacelle, hub or blades to finish seams, grind, paint, etc.    When fully installed, workers need to climb up the tower to reach the narrow, restricted spaces of the nacelle, hub and blades for maintenance, inspection and repairs.  Electrical hazards have been the source of a number of fatalities and fires in wind turbines within the confined spaces.   An electrical incident or spark that occurs in the nacelle can quickly engulf a worker whose only way to exit the space is to descend a several hundred foot ladder or to climb on the roof of the nacelle. Some nacelles are made with polystyrene type foam which is extremely flammable and adds to the fire risk.  Nitrogen used in the accumulator, off-gassing of construction materials, poor ventilation and sources such as decomposing birds or rodents, can create a hazardous atmosphere.  And if something goes wrong inside a wind turbine, the challenges to rescue are significant.      The National Fire Protection Association is developing a Best Practices Document for confined space entry. This document will address gaps in existing standards and will be more prescriptive in describing things like how to identify potentially toxic atmospheres and select the proper gas monitor for entry and how to include the evaluation of adjacent spaces into your confined space entry program.    This is a document that is looking to go beyond the minimum standards and will provide those looking to develop a “gold star” confined space entry program with the information they need to do so.  Please email me at for further information and/or leave a comment below for discussion.  I look forward to hearing from you!
Operating room

Does NFPA 99 require smoke purge in operating rooms?

One question that I have received quite often since the publishing of the 2012 edition of NFPA 99, Health Care Facilities Code, is whether or not windowless anesthetizing locations still require smoke purge systems. The answer to this is that the 2012 edition does not require it. What had previously been in NFPA 99 and previously NFPA 56A was language that remained essentially the same for years and was in the 2005 edition as follows: “ Supply and exhaust systems for windowless anesthetizing locations shall be arranged to automatically vent smoke and products of combustion. Ventilating systems for anesthetizing locations shall be provided that automatically (1) prevent recirculation of smoke originating within the surgical suite and (2) prevent the circulation of smoke entering the system intake, without in either case interfering with the exhaust function of the system.” My research shows this requirement to have first appeared in NFPA 56A in the 1960 edition. The way it was presented and worded has been slightly altered throughout the years but the intent that the smoke and products of combustion be vented and that recirculation be prevented had remained. When NFPA 99 was reorganized for the 2012 edition the requirement was not incorporated in the new Chapter 9, Heating, Ventilating, and Air Conditioning. In the current revision process the technical committee on Mechanical  Systems has proposed language that specifically states smoke purge is not required in windowless anesthetizing locations. The main substantiation for this is that the requirement is considered to be a relic as when it was first incorporated into an NFPA requirement the use of flammable anesthetics was common and therefore the fire hazards in these rooms was much higher.

Oxygen Deficient Environments in Confined Spaces

It is generally recognized that lack of oxygen is the leading cause of death in confined spaces. You cannot see or smell a oxygen deficiency therefore the hazard is not readily apparent to someone entering an oxygen deficient environment. The only way to determine if a confined space has sufficient oxygen is to test the atmosphere with a calibrated gas monitor. The air we breathe contains approximately 20.9 % oxygen. Most of the remaining 79% is made up of nitrogen with smaller quantities other gases such as argon and carbon dioxide. Interestingly, contrary to what most people think, the percentage of oxygen in the air remains the same even at higher elevations. However because the air at higher elevations is less “dense”, there are fewer molecules of everything present, including oxygen. Less oxygen molecules means it is it potentially harder to breathe despite the fact that a gas monitor will still read 20.9%. Low levels of oxygen can lead to impaired judgment, lack of coordination, behavior changes, dizziness, fatigue and ultimately collapse and death. Sometimes workers think they can “hold their breath” for a second to enter a space quickly without testing or ventilation.  But even one breath of oxygen deficient air could prevent your muscles from responding so that you cannot have the strength to escape the space even if conscious.  Those with coronary, pulmonary, or circulatory disease may feel symptoms before others. I once investigated a confined space incident in which only one of three workers was dizzy and passed out.  The atmosphere was later tested and found to have a slightly lower oxygen level of approximately 18-19.5 %.  The only worker affected was the one who had a pre-existing cardiac condition.   Low oxygen levels occur from chemical or biological processes or reactions that either consume or displace oxygen from the confined space. Common causes of oxygen deficiency include: Rusting-(rusting is an oxidation process that consumes oxygen). Combustion-(all sources of combustion such as propane heaters, welding, consume oxygen). Displacement by other gases- (such as Nitrogen purging, inerting, welding gases) Decomposition of Organic Matter (Micro-organisms consume oxygen and produce flammable methane gas that can also displace oxygen While most gas monitors will not alarm until 19.5% (OSHA allowable lower limit for entry), it is recommended that you establish a policy to require 20.9 % oxygen prior to entry. If you test the atmosphere in a confined space and it is anything OTHER THAN 20.9% you should investigate the source of this oxygen deficiency and ventilate the space prior to entry, retesting until the oxygen level is maintained at 20.9%.  With so many variables and potential hazards in confined spaces, you should strive to maintain the atmosphere as close to “normal” as possible.   NFPA is in the process of developing a Best Practices Document for Confined Space Entry.  One item that we will likely include as a best practice is to prohibit entry into confined spaces where oxygen levels are less than 20.9% and to ventilate the space until the levels reach 20.9%.   You may wish to sign up for the alerts for the document that is being developed by going to and clicking on the SIGN UP FOR EMAIL ALERTS link above the tabs. An email will be sent notifying you of any meetings or additions to the document information page related to the confined space document. If you have ideas for what should be included in this document or would like to be involved in document development please let us know! Task groups to develop draft chapters of the document are now being formed.  If you have an interest or special expertise in a particular area let us know how to contact you! 
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