The National Electrical Code addresses hazardous conditions that create the potential for fires to occur. Environments that pose fire or combustion hazards are listed in Articles 500-510. Requirements covering specific types of facilities that pose additional hazards, such as bulk storage plants or motor fuel dispensing locations, are explained in Articles 511-516.
NEC Section (C)(2)(1) describes Class II, Division 2 locations classifications. These are listed as:
1. Locations where some combustible dust is normally in the air but where abnormal operations may increase the suspended dust to ignitable or explosive levels.
2. Locations where combustible dust accumulations are normally not concentrated enough to interfere with the operation of electrical equipment unless an “infrequent equipment malfunction” occurs that increases the level of dust suspended in the air.
3. Locations where combustible dust concentrations in or on electrical equipment may be sufficient to limit heat dissipation or that could be ignited by failure or abnormal operation of electrical equipment.
A variety of airborne environmental conditions that require classification are listed in Article 500. Class I covers locations specified in Sections [500.5(B)(1)] and [500.5 (B)(2)] where flammable gases or vapors are present, or could exist in the air in high enough quantities that they could produce explosive or ignitable mixtures. Section [500.5(B)(1) FPN 1] provides examples of locations usually included in Class I as the following:
1. Where volatile flammable liquids or liquefied flammable gases are transferred from one container to another.
2. Interiors of spray booths and areas in the vicinity of spraying and painting operations where volatile flammable solvents are used.
3. Locations containing open tanks or vats of volatile flammable liquids.
4. Drying rooms or compartments for the evaporation of flammable solvents.
5. Locations with fat and oil extraction equipment that uses volatile flammable solvents.
6. Portions of cleaning and dyeing plants where flammable liquids are used.
7. Gas generator rooms and other portions of gas manufacturing plants where flammable gas may escape.
8. Pump rooms for flammable gas or for volatile flammable liquids that are not adequately ventilated.
9. The interiors of refrigerators and freezers where flammable materials are stored in open or easily ruptured containers.
10. All other locations where ignitable concentrations of flammable vapors or gases are likely to occur in the course of normal operations.
TYPES OF SAFETY LIFELINES FOR CONSTRUCTION AND WORKS BASIC INFORMATION AND TUTORIALS
There are three basic types of lifelines:
1) vertical
2) horizontal
3) retractable
All lifelines must be inspected daily to ensure that they are
- free of cuts, burns, frayed strands, abrasions, and other defects or signs of damage
- free of discolouration and brittleness indicating heat or chemical exposure.
1) Vertical Lifelines
Vertical lifelines must comply with the current edition of the applicable CSA standard and the following minimum requirements:
- Only one person at a time may use a vertical lifeline.
- A vertical lifeline must reach the ground or a level above ground where the worker can safely exit.
- A vertical lifeline must have a positive stop to prevent the rope grab from running off the end of the lifeline.
Vertical lifelines are typically 16-millimetre (5/8-inch) synthetic rope (polypropylene blends).
2) Horizontal Lifelines
The following requirements apply to any horizontal lifeline system:
- The system must be designed by a professional engineer according to good engineering practice.
- The design can be a standard design or specifically engineered for the site.
The design for a horizontal lifeline system must
- clearly indicate how the system is to be arranged, including how and where it is to be anchored
- list and specify all required components
- clearly state the number of workers that can safely be attached to the lifeline at one time
- spell out instructions for installation, inspection, and maintenance
- specify all of the design loads used to design the system.
The system must be installed, inspected, and maintained in accordance with the professional engineer’s design. Before each use, the system must be inspected by a professional engineer or competent worker designated by a supervisor. A complete and current copy of the design must be kept on site as long as the system is in use.
3) Retractable Lifelines
Retractable lifelines consist of a lifeline spooled on a retracting device attached to adequate anchorage. Retractable lifelines must comply with CAN/CSAZ259.2.2- M98.
In general, retractable lifelines
- are usually designed to be anchored above the wo rker
- employ a locking mechanism that lets line unwind off the drum under the slight tension caused by a user’s normal movements
- automatically retract when tension is removed, thereby preventing slack in the line
- lock up when a quick movement, such as that caused by a fall, is applied
- are designed to minimize fall distance and the forces exerted on a worker’s body by fall arrest.
Always refer to the manufacturer’s instructions regarding use, including whether a shock absorber is recommended with the system.
Any retractable lifeline involved in a fall arrest must be removed from service until the manufacturer or a qualified testing company has certified it for reuse.
THE DANGERS OF ASBESTOS - BASIC INFORMATION AND TUTORIALS
What are the dangers of inhaling asbestos in construction?
Inhaling asbestos dust has been shown to cause the following diseases:
• asbestosis
• lung cancer
• mesothelioma (cancer of the lining of the chest and/or abdomen).
Asbestosis is a disease of the lungs caused by scar tissue forming around ve ry small asbestos fibres deposited deep in the lungs. As the amount of scar tissue increases, the ability of the lungs to expand and contract decreases, causing shortness of breath and a heavier wo rkload on the heart.
Ultimately, asbestosis can be fatal.
Lung cancer appears quite frequently in people exposed to asbestos dust.While science and medicine have not yet been able to explain precisely why or how asbestos causes lung cancer to develop, it is clear that exposure to asbestos dust can increase the risk of contracting this disease.
Studies of asbestos wo rkers have shown that the risk is roughly five times greater than for people who are not exposed to asbestos.
Cigarette smoking, another cause of lung cancer, multiplies this risk . Research has shown that the risk of developing cancer is fifty times higher for asbestos workers who smoke than for workers who neither smoke nor work with asbestos.
Mesothelioma is a relatively rare cancer of the lining of the chest and/or abdomen.While this disease is seldom observed in the general population, it appears frequently in groups exposed to asbestos.
Other illnesses—There is also some evidence of an increased risk of cancer of the stomach, rectum, and larynx. However, the link between asbestos exposure and the development of these illnesses is not as clear as with lung cancer or mesothelioma.
The diseases described above do not respond well to current medical treatment and, as a result, are often fatal.
Inhaling asbestos dust has been shown to cause the following diseases:
• asbestosis
• lung cancer
• mesothelioma (cancer of the lining of the chest and/or abdomen).
Asbestosis is a disease of the lungs caused by scar tissue forming around ve ry small asbestos fibres deposited deep in the lungs. As the amount of scar tissue increases, the ability of the lungs to expand and contract decreases, causing shortness of breath and a heavier wo rkload on the heart.
Ultimately, asbestosis can be fatal.
Lung cancer appears quite frequently in people exposed to asbestos dust.While science and medicine have not yet been able to explain precisely why or how asbestos causes lung cancer to develop, it is clear that exposure to asbestos dust can increase the risk of contracting this disease.
Studies of asbestos wo rkers have shown that the risk is roughly five times greater than for people who are not exposed to asbestos.
Cigarette smoking, another cause of lung cancer, multiplies this risk . Research has shown that the risk of developing cancer is fifty times higher for asbestos workers who smoke than for workers who neither smoke nor work with asbestos.
Mesothelioma is a relatively rare cancer of the lining of the chest and/or abdomen.While this disease is seldom observed in the general population, it appears frequently in groups exposed to asbestos.
Other illnesses—There is also some evidence of an increased risk of cancer of the stomach, rectum, and larynx. However, the link between asbestos exposure and the development of these illnesses is not as clear as with lung cancer or mesothelioma.
The diseases described above do not respond well to current medical treatment and, as a result, are often fatal.
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