If your workplace has a confined space, you need to understand everything about them, the dangers, the regulations, the standards of what type they are, everything. Because confined spaces are a very dangerous place for employees, and without a comprehensive policy, employees can get hurt of worse die. So, when working on a confined space policy, the first place to start is with OSHA, as they have extensive things to say concerning confined spaces.
According to OSHA 1910.146, the definition of a confined space is as follows:
• Is large enough for an employee to enter fully and perform assigned work;
• Is not designed for continuous occupancy by the employee; and
• Has a limited or restricted means of entry or exit.
These spaces may include underground vaults, tanks, storage bins, pits and diked areas, vessels, silos and other similar areas.
By definition, a permit-required confined space has one or more of these characteristics:
• Contains or has the potential to contain a hazardous atmosphere;
• Contains a material with the potential to engulf someone who enters the space;
• Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section; and/or
• Contains any other recognized serious safety or health hazards.
To learn more about Permit Required Confined Spaces, check out OSHA’s publication 3138 here
Why care about Confined Spaces?
As an Owner, Safety Manager, Safety Coordinator, Site Manager or other related title, you must have knowledge and understanding of the serious risks for your employees that work in confined spaces. It is imperative that written procedures to protect your employees, contract workers and representatives from entering permit spaces must be developed and made available to all parties. To help you evaluate your workplace to determine if spaces are permit spaces, this Decision Flow Chart is a useful tool. If it is, the employer must inform exposed employees of their existence, hazards they pose and location. Effective measures must be taken to prevent employees from entering permit spaces if they are not allowed. You must be prepared to deal with increased risk of exposure engulfment, entrapment and hazardous atmospheric conditions. These issues would not normally come up in an open workplace/setting. For further info, you can review the OSHA Permit Required Confined Spaces article.
Gas Dangers in Confined Spaces
Confined spaces may contain toxic hazards that can be detected only through testing. Oxygen (O2) deficiency, hydrogen sulfide (H2S), carbon monoxide (CO), and methane (CH4) are common hazards in confined spaces that can be detected with a portable gas monitor. Depending on the industry, other gas hazards may be present. Relying on a portable gas detector for H2S readings, and not sense of smell, is the most reliable method of ensuring that workers are notified well before dangerous levels are reached. In the range of 200 to 300 ppm, eye inflammation, respiratory tract irritation, and a loss of consciousness can occur. When levels of H2S reach 500 to 700 ppm, death will occur within 30 minutes to an hour.
Gas Safety is important. The risks can be divided into three categories: combustible gas, toxic gas, and high or low oxygen levels. Making the worker’s assignment as safe as possible is the employer’s responsibility. A work location assessment is a requirement.
• Combustible gas
For combustion to occur, the air must contain a minimum concentration of combustible gas or vapor. This quantity is called the lower explosive limit (LEL). At concentrations equal to or greater than this, combustion will occur in the presence of a suitable ignition source such as a spark or hot surface. For most combustible gases and vapors, the LEL is less than 5% by volume, and a combustible atmosphere is usually described as ” hazardous” at 10% LEL.
Some examples that present dangers are as follows: storage vessels which have contained hydrocarbon fuels and oils, and fuel leaks in pipelines, gas cylinders and engine-driven plant. For workers in sub- surface environments such as sewers and pits, methane is an almost universal danger. It’s an odorless gas underground and it’s formed by decaying organic matter
• Toxic gases and vapors
Depending on the environment and the nature of the work, confined space workers may be exposed to any of a large number of toxic compounds. For example, generators used in a confined space produce carbon monoxide in the exhaust fumes thereby creating a serious poisoning risk. Workers near vehicle traffic may be exposed to carbon monoxide and nitrogen dioxide from exhaust fumes. Subsurface hazards are hydrogen sulphide and carbon dioxide due to bacteria decomposition.
• High or Low Oxygen Levels
The normal concentration of oxygen in fresh air is 20.9%. If it falls below 19.5% or goes above 23.5%, an atmosphere is considered hazardous. If the concentration falls to 17%, mental and physical agility are noticeably impaired; death comes very quickly if it drops only a few percent more. At these levels, unconsciousness takes hold so rapidly that the victim will be unaware of what is happening.
How does a location get oxygen-deficient? Numerous reasons such as: the result of oxygen displacement by a toxic or inert gas, microbial action, oxidation caused by rusting metal, combustion, and absorption.
High oxygen levels are also dangerous. As with too little, too much will impair the victim’s ability to think clearly and act sensibly. Moreover, oxygen-enriched atmospheres represent a severe fire hazard. From clothing to grease, materials which would not normally burn become subject to spontaneous combustion under these conditions. Common causes of oxygen enrichment include leaks from welding cylinders and even from breathing apparatus.
Need more components of a Confined Space Program? The EHS Center has more available here
Nowadays, multi-sensor confined space instruments are increasingly much less expensive, rugged, compact, easy to use than ever before. A confined space gas detector kit makes stratified testing easy and generally includes a multi-gas monitor with pump, 10-foot sampling hose for pre-testing (longer lengths are available), spare batteries (rechargeable or alkaline), quad-gas cylinder for bump testing, and calibration with gas regulator, all conveniently contained in a rugged carrying case.