Identifying a confined space
Hazards of confined spaces
Permit required/Non-permit required confined space
Permit required confined space entry program
Entering a permit-required confined space
Alternate entry procedures for permit required confined spaces
Confined spaces can contain deadly hazards for employees who are required to work within these areas. The Occupational Safety and Health Administration (OSHA) has defined such hazardous spaces as "Permit Required Confined Spaces" and in January 1993, OSHA issued a rule on Permit Required Confined Spaces (29 CFR 1910.146). This regulation is intended to prevent more than 5,000 serious injuries and 54 fatalities each year.
Confined spaces include, but are not limited to, sewage digesters, sewer silos, tunnels, manholes, utility vaults, pumping stations, storage tanks, process vessels, pits, vats, vaults or similar types of enclosures with limited access and without proper ventilation. Entry into confined spaces may be for the purpose of inspection, testing of equipment, maintenance (repair and cleaning) or an emergency.
The characteristics of a confined space are:
The most common hazard in a confined space is a hazardous atmosphere. This hazard primarily deals with the air in the confined space and includes oxygen-deficient, oxygen-enriched and flammable or toxic atmospheres.
An oxygen-deficient atmosphere (not enough oxygen in the space) has less than 19.5 percent of available oxygen. Any confined space with less than 19.5 percent oxygen should not be entered without an approved self-contained breathing apparatus (SCBA) or supplied air hose with an escape pack.
The low oxygen level in a confined space can be caused by chemical reactions, sewage or other decomposing organic matter such as domestic waste and plant life. The work being done in the space or certain chemical reactions can also lower the oxygen level. In order to have a safe working environment in a confined space, the oxygen level must be between 19.5 and 23.5 percent. Any level below 19.5 percent is dangerous and will affect the worker's health and safety. Levels below 10 percent can cause unconsciousness and levels below 8 percent can quickly cause death.
An oxygen-enriched atmosphere (above 23.5 percent) will cause flammable materials, such as clothing and hair, to burn violently when ignited. Consequently, never use pure oxygen to ventilate a confined space. Ventilate with normal, clean outside air.
Flammable atmospheres, due to the build-up of methane or other flammable chemicals can also occur in confined spaces.
A flammable atmosphere will only occur when a certain chemical/oxygen mixture is present. Below this level, called the Lower Flammable Limit (LFL) or above this level, called the Upper Flammable Limit (UFL), the substance will not ignite. Between the LFL and the UFL, a source of ignition (e.g., sparking or electrical tools) could result in an explosion. According to OSHA, a space is unsafe if the flammable gas or vapor level is above 10% of the LFL and workers shall not enter.
For example, methane is the most common flammable gas in sewers. It is generated by decomposing organic material. The LFL for methane is 5%. When the levels reach 10% of that level, or .5% methane, the space may not be entered.
Toxic gases and vapors come from a wide variety of sources. Hydrogen sulfide and carbon monoxide is produced by sewage and other rotting organic materials. Other toxic substances may have been spilled or dumped into a sewer system. According to OSHA, if toxic chemicals are present that exceed the OSHA Permissible Exposure Limit and can cause death or serious illness, or if any other chemical is present that can immediately endanger the workers' lives or health, the atmosphere is considered hazardous.
OTHER CONFINED SPACE HAZARDS
There are a number of other potential physical and safety hazards inside a confined space. These include engulfment, falling objects, temperature extremes, noise, slips and falls.
Engulfment means the surrounding and effective capture of a person by a liquid or finely granulated substance that can be inhaled and cause death by strangulation, constriction or crushing. Loose, granular material stored in bins and hoppers, such as grain, sand, coal, or similar material, can engulf and suffocate a worker. The loose material can crust or bridge over in a bin and break loose under the weight of a worker.
Workers in confined spaces should be aware of the possibility of falling objects, especially in spaces which have topside openings, and where work is being done above the worker.
Extremely hot or cold temperatures can present problems for workers. For example, if the space has been steamed, it should be allowed to cool before any entry is made.
Noise within a confined space can be amplified because of the design of the space. Excessive noise can not only damage hearing, but can also affect communication, such as causing a shouted warning to go unheard.
Slips and falls can occur on wet surfaces causing injury or death to workers. Also, a wet surface will increase the likelihood and severity of electric shock in areas where electrical circuits, equipment, and tools are used.
Chemicals whose exposure can restrict a workers ability to escape from the space.
Any other hazard that could cause serious injury or death.
The employer is required to evaluate the workplace to determine if there are any potential or actual hazards in any confined spaces. Based on the hazards present, each space will be categorized as a permit required or a non-permit required confined space.
A permit required confined space has one or more of the following characteristics:
A non-permit required confined space is a confined space that does not contain any hazard capable of causing death or serious physical harm, and has no atmospheric hazard, nor the potential for any atmospheric hazard. These conditions must be verifiedby the employer.
If there are permit required spaces in the workplace, the employer must inform exposed employees of the existence and location of these spaces and prevent unauthorized entry into these spaces.
The entrant is the employee who will enter the confined space to do the work. Prior to being allowed to enter a permit required confined space, the employee must receive training and be able to identify the hazards that they may face during entry. The employer is responsible for making sure that entrants use all personal protective clothing and safety equipment required for a safe entry. The entrant is responsible for self-monitoring, both by using monitoring equipment and by continually checking his or her physical conditions in the space.
The attendant is the person stationed outside the permit required confined space. He or she must be in constant communication with the entrant -- to monitor the entrant's status and to alert the entrants of the need to evacuate the space. For the entrant, the attendant is the only communication link to the outside of the confined space. The attendant is responsible for making sure the entrant remains safe. There are a number of things the attendant must do to protect the entrant:
NOTE: The standard allows attendants to be assigned to monitor more than one permit space, provided that their duties (listed above) can be effectively performed for each permit space that is monitored. Such a situation should almost never occur for sewer maintenance or wastewater treatment plant workers because the attendant must be in constant communication with all entrants, be able to monitor the conditions in all confined spaces, and be able to perform all of his or her duties without distraction. Unless the spaces being monitored are right next to each other, it is unlikely that these conditions could be met.
If the employer decides that its employees will enter permit-required confined spaces, a written confined space entry program must be developed and implemented. It must be available for inspection by employees and their authorized union representatives. In this program, the employer must describe how he/she will comply with the requirements of the standard. The written program must include the following:
Confined spaces can be deadly. Therefore, entry into a confined space should be well planned to deal with any potential hazard. Entry is defined as occurring when any part of the body passes through the opening of a confined space. Prior to entry, an entry permit should be completed and signed by the entry supervisor verifying that the space is safe to enter. The entry permit must also be posted at the entrance or otherwise made available to entrants before they enter the permit space.
An entry permit must be filled out before an employee enters a confined space (and posted at or near the confined space.) It should contain the following types of specific information concerning:
The entry permit is the document that certifies that the employer complies with the requirements of the standard for entries in permit required confined spaces. Also, the entry supervisor must close off the space and cancel permits when an assignment has been completed or when prohibited conditions exist. All new conditions must be noted on the canceled permit and used in revising the permit space program. The standard also requires the employer to keep all canceled entry permits for at least 1 year.
Before entering the area, workers must always test for oxygen content of the air, then flammable or explosive gases or vapors, and finally toxic chemicals such as hydrogen sulfide. This sampling should be done with a remote monitor on a wand attached to the toxic gas meter. The monitor should be able to reach the lowest point in the confined space. Oxygen monitoring should be done first as the explosive gas monitor will not be accurate if there is an oxygen deficiency.
It is important to remember that some gases or vapors are heavier than air and will settle at the bottom of the confined space. Also, some gases are lighter than air and will be found around the top of the confined space. Thus, during the sampling process it will be necessary to test all areas (top, middle and bottom) of the confined space.
In sewers or other areas which are part of a continuous system where new hazards may enter at any time, continuous air monitoring must be conducted.
Many monitors must be calibrated after every use in an environment that has similar heat and humidity conditions as the confined space. The manufacturer's recommendations should be strictly followed.
Many monitoring devices must be "zeroed" before each use by exposing the monitor to clean air and setting the indicator to zero. Just turning on the instrument is not enough. The indicator must be zeroed frequently in a clean environment when monitoring an area for an extended period of time.
If the atmosphere is found to lack oxygen, or contain toxic gases and vapors, the space must be ventilated before entry. An air powered ventilator placed at the top of the opening can blow breathable air into the space. Just because air is blowing into a space does not mean that the work areas are being effectively ventilated. Toxic gasses that float at the top or sink to the bottom of a space, or that "hide" in "dead areas" may be not be ventilated properly. Never assume that the space is safe until it is monitored again. It is also very important that ventilation continue while the employee is working in the space. A trained person must determine whether the air must be blown or sucked, and how the ventilation should be conducted.
The air intake should be placed in an area that will draw in fresh air only. Ventilation should be continuous where possible, because in many confined spaces the hazardous atmosphere will form again when the flow of air is stopped.
The forced air ventilation should ventilate the immediate areas where an employee is or will be present within the space and should continue until all employees have left the space.
Personal protective equipment is used to protect workers only after all other feasible means have been used to control or eliminate hazards. A full body or chest harness and a lifeline should be used when entering a confined space.
In some situations, a respirator will also be needed. A respirator will allow the employee to breathe without inhaling toxic gases or particles.There are two basic types of respirators, air-purifying, which filters dangerous substances from the air; and air-supplying, which delivers a supply of safe breathing air from a tank or an uncontaminated source. An air-line respirator can only be used if the worker has a rescue bottle.
Air-purifying respirators can filter dangerous substances from the air, but they provide no protection in an oxygen deficient environment and should not be used when working in a confined space. Only air-supplying respirators (SAR/SCBA) should be used in confined spaces that have low oxygen levels or high levels of toxic gasses. They can supply the employee with safe breathing air from a tank or an uncontaminated source nearby.
In vertical entries, the safety harness should be attached to a retrieval device that will allow quick removal of an employee in the event of an emergency. In the event of an emergency, the attendant located on the outside should be able to initiate a rescue without entering the space.
Hard hats, safety goggles, face shields, gloves, safety shoes, boots, disposable suits, earplugs or muffs, non-sparking flashlight and tools may also be needed when entering a confined space.
An emergency in a confined space can kill an entrant in a matter of minutes. In order to facilitate rescue without having a rescuer enter a space, OSHA requires the use of "non-entry" rescue, retrieval systems or methods, such as tripods and winches to lift unconscious or injured entrants out of a space that is more than five feet deep.
Where entry must be made for rescue, OSHA allows rescue to be performed either with the facility's trained in-house rescuers or by contracting to an outside rescue service.
In-house Rescue: Rescuers must have extensive training. No employee -- even an attendant -- is authorized to enter a space to rescue an entrant unless he or she has had extensive training in personal protective and rescue equipment. This includes actual practice in making simulated rescues and CPR. NOTE: Even a trained attendant may not enter a space to make a rescue -- even if he or she is trained -- until another attendant has arrived.
Outside Rescue: A very controversial part of the OSHA's Confined Space regulation is the ability of employers to use outside rescuers such as fire departments. If this is done, the rescue service must be informed of the hazards they may confront, and the rescue service must have access to all permit spaces so that the rescue service can develop appropriate rescue plans and practice rescues before a rescue must be made. NOTE: Never assume that the local fire department or rescue squad is trained or equipped to make a confined space rescue unless the requirements listed above have been met. It's not enough to just assume you can call 911 in an emergency.
Proper training, careful preparation and good judgment are essential to safe confined space entry. The employer is mandated to provide initial and refresher training to equip employees with the understanding, skills and knowledge necessary to perform the confined space entry safely.
Training should be provided to each affected employee before the employee starts performing assigned duties in confined spaces and must be certified by the employer. Authorized entrants, attendants, supervisors and rescuers require different levels of training according to their specific duties and responsibilities.
While OSHA does not require any specific number of hours for training, AFSCME recommends that the minimum amount of training for an entrant or attendant should be at least 24 hours. (Where there has been previous training on respirator use and air monitoring, 16 hours may be sufficient.) Training for rescuers should be at least 40 hours.
Where the employer can prove that the only hazard present in a confined space is an actual or potential atmospheric hazard that can be controlled through ventilation alone, the employer can use alternate entry procedures. In short, this means that a permit is not required before entry, rescue arrangements do not have to be made and no attendant is required. Because fewer workers are needed for alternate entry, employers may try to apply this section, even when it is not justified.
It is extremely important that any employer who attempts to use alternate entry procedures follow the requirements of Paragraph c(5) of the 1910.146
The employer must do the following to use alternate entry procedures:
Even with alternate entry procedures, the following requirements must be met before entry:
By properly preparing and educating employees about the hazards involved with confined spaces, injuries and deaths can be prevented. For additional information on confined spaces, contact the AFSCME Research Department.
material was produced under grant number 46C3-DT05 from
the Occupational Safety and Health Administration, U.S. Depart-
ment of Labor. It does not necessarily reflect the view or policies of
the U.S. Department of Labor, nor does mention of trade names,
commercial products, or organizations imply endorsement by the