Joe Gurican, who teaches a confined space awareness class, believes confined space deaths typically occur for two reasons. First, employers and workers fail to recognize and control the hazards associated with confined spaces, and secondly, they conduct inadequate or incorrect emergency response, resulting in the death of the initial entrant, the would-be rescuer or both.
The first step in preventing confined space deaths is understanding the difference between permitted and non-permitted confined spaces. A permit-required confined space contains or has potential to contain a hazardous atmosphere, contains the potential for engulfment, is an internal configuration that can trap or asphyxiate the entrant or poses any other serious safety and health hazards.
“A permit system and a written permit-required confined space program must be developed if employees are going to enter permit spaces,” says Gurican, an instructor for the Safety Center.
A permit space may be reclassified as a non-permit space if it poses no actual or potential atmospheric hazards and if all hazards with the space are eliminated. If an entry must be made to eliminate the hazards, the entry must be done using the permit system. The elimination of hazards must be documented and certified by the employer.
“Employers must inform the employees of the existence of any permit spaces through signs or other equally effective means and prevent unauthorized entry,” Gurican adds.
Typical permit-required spaces include chemical storage tanks, pipelines, lift stations, tunnels, waste water tanks, air handling units, catch basins, furnaces, sewers, boilers, underground, retention basins, man holes, valve pits, grain bins and waste storage pits. According to Gurican, “Sewers are considered a permitted confined space because you never know what someone has dumped upstream that could flow into the work space.”
A confined space has limited means of egress, can be bodily entered and is not designed for continuous occupancy. Typical non-permit-required spaces include utility closets, cable vaults, storage vaults and utility subbasements. In most cases, a trench is not considered a confined space.
Entrants, Attendants and Supervisors
Authorized entrants must know the hazards that may be faced during entry, including information on the type of hazard and the signs and symptoms of oxygen deficiency. Authorized entrants should be able to recognize any warning signs or symptoms of exposure to a dangerous environment. They must use equipment as required and must communicate with the attendant as necessary to enable the attendant to monitor their status. It also is the task of entrants to alert the attendant whenever hazards arise.
Once an entrant detects a prohibited condition, he or she should exit the permit space as soon as possible. An entrant also should quickly exit a permit space if an order to evacuate is given by the attendant or supervisor or if an evacuation alarm is activated.
The attendant is required to know the hazards that may be faced during entry and be aware of the potential behavioral effects of hazard exposure on authorized entrants. Attendants also continuously should maintain an accurate count of authorized entrants in the permit space and remain outside the permit space during entry operations until relieved by another attendant. Attendants should perform non-entry rescues or other rescue services as part of the employer's on-site rescue procedure.
Entry supervisors should review the permit to ensure that all tests have been conducted and all procedures and equipment are in place before signing the permit. They also must terminate entry and cancel permits, verify that rescue services are available and remove unauthorized individuals who enter the space.
Rescue Services and Procedures
Employers must ensure that at least one standby person at the site is trained and immediately available to perform rescue and emergency services. It is the responsibility of employers to ensure that each member of the rescue service is provided with and is trained to use the personal protective equipment and rescue equipment necessary for making rescues from permit spaces.
“It's not a good idea to rely on the fire department for the rescue services, because they can't be there when you want them. The attendant should be trained to rescue and have all the equipment necessary to do so,” says Gurican.
Each member of the rescue service is tasked with practicing permit space rescues at least once every 12 months by simulating rescue operations in which they remove dummies or volunteer employees from the actual permit spaces or from representative permit spaces. Representative permit spaces must, with respect to opening size, configuration and accessibility, simulate the types of permit spaces from which rescues will be performed.
In addition to initial training, refresher training should be conducted as needed and the employer must certify that the training has occurred. Training should be provided so that all employees acquire the understanding, knowledge and skills necessary for the safe performance of the duties assigned. Training should be provided when there is a change in assigned duties and whenever an employee is assigned a task for which they have not been trained.
Monitoring and Instrumentation
An important aspect of training for confined space entry is to share with employees the deadly nature of confined spaces. Confined spaces can be deadly because of the potential for engulfment, oxygen deficiency, oxygen enrichment, flammable gases or vapors, combustible dusts, toxic substances and other physical hazards. Other health hazards that could impact employee safety include electrical equipment, mechanical equipment, poor visibility, biohazards, claustrophobia, noise, radiation and temperature.
“If workers are taking a meter into a confined space with them, they need to know how to use it. They should know what the alarms sounds like, how to turn it on and off, etc.,” Gurican warns. “Workers should check all the monitors before they enter a confined space. Then again, don't just follow the meters; workers should let their bodies tell them when it's time to leave a confined space.”
Engulfing materials include liquids or loose solids such as grain, sand or other granular material. “People cannot escape when caught in moving loose solids and usually suffocate,” says Gurican. “Workers often get engulfed when in-feed or out-feed lines are inadvertently opened or activated. Entrapment occurs when the space is configured in a way that can trap a worker.”
Purging, inerting, flushing or ventilating the permit space is necessary to eliminate or control atmospheric hazards, though controlling these hazards through forced air ventilation does not necessarily eliminate them. The employer must demonstrate that forced air ventilation will control all hazards in the space.
For atmospheric testing, hazards must be tested in this order: oxygen content, combustibility/flammability and toxic atmospheres. Also, entrants must be allowed to observe monitoring.
A hazardous atmosphere in a confined space has one or more of the following: flammable gas, mist or vapor, flammable dusts and oxygen content below 19.5 percent or above 23.5 percent. The physical symptoms of oxygen deficiency include:
- 19.5-16 percent: Fatigue, mild impaired coordination
- 16-12 percent: Increased breathing rate and pulse; impaired coordination, perception or judgment
- 12-10 percent: Further increased breathing rate, blue lips, mental confusion
- 10-8 percent: Fainting, nausea, vomiting, mental confusion within a few minutes
- 8-6 percent: Collapse, death within eight minutes
- 6-0 percent: Coma within 40 seconds, death
Extra oxygen typically is from leaking oxygen cylinders used for oxyacetylene torches. Oxygen above 23.5 percent is a fire or explosion hazard. Flammable gases, vapors or dusts will ignite from a spark or a flame if they are above the lower flammable limit. A confined space cannot be entered if the gas or vapor levels are higher than 10 percent above the lower flammable limit.
Working with Chemicals
The most common toxic chemicals in confined space fatalities are hydrogen sulfide and carbon monoxide, which comes from operating internal combustion engines in or near a confined space. Other chemicals in the atmosphere can come from welding fumes or vapors from liquid residues in storage tanks. Chemicals are classified as having physical hazards if they are explosive, compressed gas, combustible liquids, flammable, unstable, water reactive or oxidizers. A chemical is considered a health hazard if it can cause cancer, is poisonous, can cause harm to skin, internal organs or the nervous system, is corrosive or if it can cause allergic reactions after repeated exposure.
Material safety data sheets from chemical manufacturers provide additional information regarding safe use of the product. Each MSDS should tell you common name and chemical name of the material, the name address and phone number of the manufacturer, emergency phone numbers for immediate hazard information and the date the MSDS was written.
“The best training materials for using testing equipment are the manufactures guidelines,” Gurican says.
An MSDS also should contain a list of the hazardous ingredients, health hazards of the chemical, identification of chemical and physical properties, first aid and emergency information and safe handling guidelines.
“A lot of chemicals have a latency component to them and you might not immediately feel the effects of exposure, but you could develop a problem later if you don't follow the manufacturer's guidelines and have proper ventilation, gloves and protective eyewear,” warns Gurican.
Planning for Entry
Pre-planning for confined space entry should include all parties involved and should serve the purpose of reviewing entry procedures as well as covering specific hazards inherent to the spaces being entered. It should cover all required engineering controls needed to address the space's hazards, including ventilation, space isolation, lockout/tagout of equipment and personal protective equipment. To eliminate physical hazards, lock out moving parts, blank or block steam pipes and product in feeding pipes, de-energize electrical parts or wiring.
“Always be aware of how you're setting up your equipment and where you're setting it up. If you place a fan for ventilation in the wrong place, you might be sending debris into the work space,” Gurican says.
Confined spaces can be killers. Following OSHA regulations and training employees to follow confined space regulations will save lives.
Elizabeth Wilson is a freelance writer from Sacramento, Calif. Safety Center Inc. was founded in 1934 to reduce injuries and save lives by providing safety education and training. For more information, call (800) 825-7262 or visit http://www.safetycenter.org.