WORKING IN A HAZARDOUS ATMOSPHERE

Preview The section discusses personal protective measures that might be used when the atmosphere of the lab may be unsafe. 

after procurement, you will have spent a lot of money on equipment without ever knowing whether it satisfies your requirements completely. and the PPE you bought will limit your capability and your safety to the point that you might be putting lives at risk by implementing its use. 

What lesson can be learned from this incident  

Before you wear a respirator you must ensure that you (1) have selected the correct respirator, (2) are medically fit to wear a respirator, (3) are properly fitted for a respirator, and (4) have been trained in wearing the respirator. 

Laboratory Safety for Chemistry Students, Second Edition. Robert H. Hill, Jr. and David C. Finster. 2016 John Wiley Sons, Inc. Published 2016 by John Wiley Sons, Inc. 

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Generally, it is more economical to prevent explosive atmospheres in rooms than to try to provide explosion-proof electrical equipment. Personnel should never be allowed to work in a hazardous atmosphere. Where such an atmosphere cannot be avoided through control of flammable liquids, gases, and dusts, access to the area involved should be limited and the area segregated by hoods or special ventilation. Electrical equipment on open, outdoor structures more than 8 m above-ground usually is considered free from exposure to more than temporary, local explosive mixtures near leaks (86). 

A space large enough for an employee to enter and work with restricted activities or movement may have a hazardous atmosphere. The incident occurs because of failure of recognizing the hazards associated with confined spaces. The different kinds of confined spaces for a worker in a plant are tanks, silos, storage bins, vessels, hoppers, pits, and sewer lines. Big fermenters, multieffective evaporators, boilers, and wells are also included in this list. 

Various types of hazardous atmospheres are classified to make it easier to discern the specific equipment needed to work in a given hazardous atmosphere. Most manufacturers use these classifications in their operating specifications. This classification system is clearly laid out in NFPA 497 and should be studied to get an understanding of the system. The most common classifications are Class, Division, Group, and Zone. 

Who All employees working in and around open-surface tank operations must be instructed on the job s hazards and the personal protection and first aid procedures applicable to these hazards. A trained stand-by employee with a suitable respirator must be present when it is necessary to enter a tank which may contain a hazardous atmosphere. 

Who Each employee who enters an enclosed space or who serves as an attendant must be trained in the hazards of enclosed-space entry, in enclosed-space entry procedures, and in enclosed-space rescue procedures. Also, while work is being performed in the enclosed space, an attendant with first-aid training must be immediately available outside the space. Training in accordance with general industry standard 29 CFR 1910.146 is required for employees that will enter any enclosed space that contains a hazardous atmosphere. 

One hazard associated with employees working in the cellar is the presence of a hazardous atmosphere. Because the cellar is a pit in the pad that the rigs substructure sits on, gases can easily accumulate in it. That is why it is so important for the atmosphere to be tested before workers enter the cellar. 

Section 1926.953 contains requirements for entry into and work in enclosed spaces. These include manholes, vaults, tunnels, or shafts that have a limited means of egress or entry, is not designed for employee entry under normal operating conditions, and under these normal operating conditions, does not have a hazardous atmosphere. However, it can contain a hazardous atmosphere under abnormal conditions. 

There is also the possibility that you may hear some loud noise or yelling from the lab next door and rush to that location to see if you can help. In this instance you will need to make a quick determination of what has happened, what hazards are now present (that may ordinarily not be present, such as a hazardous atmosphere), and what you can and should do to help. In an emergency situation where you are unfamiliar with the particular hazards of a lab in which you ordinarily don t work there is not time to complete a thorough review of the questions above. 

SB-2 Oxygen-Deficient Atmospheres, Depletion of the oxygen content in air by combustion or displacement with inert gas is a potential hazard to personnel throughout industry. This bulletin deals with recommended practices for the protection of personnel working in a potentially oxygen-deficient atmosphere. Supplemental to CGA P-14. (2 pages)... 

Where there may be a hazardous atmosphere or deficiency of oxygen in the area where excavation is to take place, atmospheric tests must be carried out before work starts and if necessary during the course of the work. If the excavation becomes a confined space as defined above, a CS permit will be required and must be issued before entry into the excavation. A hot work permit may also be required in some cases. 

Hazards involving normal work activities can usually be predicted by a trained IH. It is, however, very unpredictable how much airborne exposure a worker is subjected to from a particular source. Many times the same type of work conducted at one site is much different from an exposure condition at another. Inside exposures will remain more constant than outside where wind and weather conditions play a major role. For example, asbestos abatement work that is conducted in a controlled atmosphere inside should remain fairly constant if work practices such as negative air filtration are used and surfaces are wetted properly. Conversely, work on an asbestos roof on the outside, even though there is a difference in the type of asbestos, will depend more on weather conditions. Work practices such as location of the worker in relationship to the wind (up- or downstream) and how intact the shingles are as they are removed also play an important part in overall exposure. The more broken up they are the more likely an asbestos exposure will result. Although inside exposures sometimes can vary vastly with the size of an area and individual work practices, it is not usually expected to be that way. 

The name dust , is used in a variety of ways, and with different meanings. These range from the material that accumulates on the earth s surface, such as on streets and in living and working environments, to the particulate material suspended in the atmosphere. In this paper I wish to consider these two materials in terms of their chemical composition, sources and relationship between them. The names used for the two materials will be surface dust and atmospheric dust . The word aerosol may also be used for atmospheric dust but it more properly applies to the finer particles of atmospheric dust and includes liquid aerosol (i). Botfi surface and atmospheric dusts are increasingly seen to be a hazard to human beings as they are a source of intake of toxic materials such as heavy metals. For this reason study is important of the composition and sources of the dusts. 

Atmospheric releases of flammable gases such as hydrogen may lead to major fires with extensive effects on the surroundings. In activities where hazards are associated with cloud fires, there is the need of societal risk assessment that involves the estimation of hazardous zones due to the resulting thermal radiation. However, till now only limited work has been done on modeling the effects of flash fires, in a way that available techniques may be judged insufficient [47],... 

The key to safe handling of chemicals is a good, properly installed hood, and the referenced book devotes many pages to hoods and ventilation. It recommends that in a laboratory where people spend much of their time working with chemicals there should be a hood for each two people, and each should have at least 2.5 linear feet (0.75 meter) of working space at it. Hoods are more than just devices to keep undesirable vapors from the laboratory atmosphere. When closed they provide a protective barrier between chemists and chemical operations, and they are a good containment device for spills. Portable shields can be a useful supplement to hoods, or can be an alternative for hazards of limited severity, e.g., for small-scale operations with oxidizing or explosive chemicals. 

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