1. (a) Explain the methods of heat transfer that can cause the spread of fire. (b) Outline the main requirements of a safe means of escape from a building. (8) (12) (a) Methods are Conduction (e.g. through a plastic coffee cup), convection (e.g. up a chimney), radiation (e.g. from a fire) and direct burning (e.g. of any fuel such as wood) (b) Emphasis on fire resistant materials for escape route walls, ceilings and doors. Easy exit provisions with doors opening in direction of travel and self-closing. Notices identifying, and lighting of, escape routes. Good housekeeping on routes to ensure no obstacles and no flammable substances on routes. Distances form workstations into an escape route. A safe assembly point. Fire alarm and extinguisher stations on route towards safe routs. 2. (a) Outline the main factors to be considered in the siting of fire extinguishers. (b) Outline the inspection and maintenance requirements for fire extinguishers in a workplace. (4) (4) (a) Accessibility, proximity to exits, travel distances, situated at fire points, protection when required from weather or other sources of damage. (b) Maintenance is something more extensive and usually involves annual tests by a competent person according to the manufacturer's instructions in order to ensure the integrity of the extinguisher, with the removal and replacement of equipment found faulty. 3. List EIGHT features of a safe means of escape from a building in the event of a fire. (8) Issues include; at least two escape routes available in two directions from work-areas taking account of escape distances from workplace to protected zone. The fire resistant integrity of escape routes. The ability of fire doors to be easily opened in direction of escape and to self close. The need to ensure escape routes are kept free from obstructions. Appropriate siting and marking of assembly points. Fire escape notices of the appropriate type. Lighting of escape routes. Suitability for people with special needs. 4. (a) Outline TWO advantages and TWO disadvantages of using hose reels as a means of extinguishing fires. (b) Outline the main factors to consider in the siting of hose reels. (4) (4) (a) Advantages – (i) A continuous supply of water that is of a greater force and quantity than an extinguisher has. (ii) User does not need to be close to the fire. Disadvantages – (b) Issues are; accessibility (should be on, or adjacent to, an escape route e.g. on a stairwell). Recessing where possible into walls to avoid blocking escape routes. Possible sealed hole from hose to pass from stairwell into offices etc. Positioned to give maximum coverage in terms of the length of hose, where frost will not cause the water to freeze and they will not be subject to misuse or vandalism. 5. (a) (b) (4) (4) (a) Examples: starvation (removing the fuel). Smothering (Eliminating oxygen). Cooling (pouring water on to the fire) or by interfering chemically with the combustion process. (b) Harmed by being burnt, inhaling smoke, by depleted oxygen supply, falling parts of a building or by being crushed or suffering some other injury in trying to escape. 6. (a) (b) (4) (4) (a) Ignition sources include: Smoking, hot work and surfaces, electricity, reactive chemicals, and arson. (b) Control could include: Smoking - ban or restriction on smoking. Hot work and surfaces -ensuring no combustible materials are in the vicinity of hot work. Electricity - ensuring no over-loading of circuits and proper care and maintenance of electrical equipment. Reactive chemicals - control through work practices and procedures including storage. Arson - having good security arrangements including restriction of strangers in building and diligent supervision.
Inspection should be routinely carried out to ensure extinguishers are in place, have not been discharge, damaged, have pins missing or, because of a change in local conditions or work are unsuitable for the fires they are meant to deal with.
With reference to the fire triangle, outline TWO methods of extinguishing fires.
State the ways in which persons can be harmed by fire in work premises.
Identify FOUR types of ignition sources that may lead to a fire in the workplace.
Outline ways of controlling each of the ignition points identified in (a).
Tuesday 15 April 2008
Typical Examination Questions based on Element 7
Saturday 12 April 2008
Fire & Fire Safety
Legislation The Regulatory Reform (Fire Safety) Order 2005 is Law. In Scotland, The Fire (Scotland) Act 2005 In Northern Ireland the Fire Precautions (Workplace) Regulations 1997/1999 The main ways of preventing fire are by controlling fuels and ignition sources. In particular, suitable storage for highly flammable materials and selection of equipment in flammable hazardous areas. People need to know there is a fire so that they can escape. Options for detection include: Fires can be extinguished by eliminating any one side of the fire triangle. This usually involves cooling, creating a barrier between fuel and oxygen, using a chemical that interfere with fire process, or replacing oxygen with another non-flammable gas. Fire can spread by: Include Include Include For a fire to occur you must have all three sides of the fire triangle present, namely
The cornerstone of the regulations is fire risk assessment. through this the following need to be considered
* Preventing fire occurring
* Preventing fire spreading (design of premises as well as fire fighting)
* Ensuring people are adequately protected if a fire occurs - includes employees, visitors, neighbours and fire service personnel.
Emphasis is on the employer being responsible for managing risks from fire. To achieve this they need to have competence to assess and control the risks.
Oxidising agents need to be handled carefully and kept away from flammable materials.
The possibility of arson must be considered, and keeping sites secure and free from rubbish and other flammable items is important.
* Smoke,
* Flame (UV)
* Heat
* Manual (e.g. break glass).
Factors that affect ease of escape include:
* Number of fire escapes (ideally always more than two independent safe routes from any location);
* Distance to exit
* Clutter on route
* Fire integrity of escape route - fire doors that close automatically
* Ability to open fire doors - must not be locked, open outwards
* Signage
* Emergency lighting
* (Safe) assembly points
* Knowledge of procedures - staff and visitors
In general, do not use lifts. Need to make provision for disabled people including physical, visual and deaf (cannot hear alarms).
Types of extinguishing device include:
* Water from extinguisher, hose, sprinkler, deluge (cools)
* Foam (cools and seals over fuel) - good for liquids
* Power (chemical interference)
* Carbon dioxide (displaces air/oxygen) - good for electrical fires
* Fire blanket (smothers) - chip pans
* Conduction - heat moving through solid material;
* Convection - heat moving through a fluid or gas (i.e. hot air rising)
* Radiation - emission of infra-red energy that can then be absorbed and cause items to get hot
* Sparks
* Flame
* Hot surfaces
* Friction
* Electricity (including static)
* Smoking material (e.g. cigarettes)
* Solids
* Liquids
* Gas and vapour
* Oxidising agents - react with other substances to create flammable conditions, possibly without oxygen being present
* Heat - causing burns
* Smoke and fumes
* Oxygen depletion
* Structural damage to buildings etc.
* Fuel
* Oxygen
* Heat
Eliminating any will prevent a fire or extinguish one that is already going.
Element 7, Fire - hazards and control
Element covers: Fire and fire safety which on any construction site is a major concern, The element describes the hazards which can cause fires, such as poor housekeeping, not enforced smoking policies, poor equipment maintenance, and the storage of flammable materials. It is essential that a construction site has good housekeeping policies in place this effects most activities and can lead to becoming a fire risk if not enforced. Smoking around flammable materials, and the storage of such couple with bad housekeeping can lead to quite serious fire risks. Flammable materials such as wood paper not just liquids should be stored in a safe and tidy manner, with the appropriate fire fighting equipment near to hand. The storage of flammable liquids has separate legislation and if you are storing these in any significant quantity, you should look into this further. Electrical fire are not categorised as a class of fire as others are (see table below) but electricity is a cause of many fires, therefore the correct use and maintenance of supplies and equipment are essential. Class Fuel/Heat source Class A Ordinary combustibles Class B Flammable liquids Class C Flammable gases Class D Combustible metals Class E Electrical equipment Class F Cooking oil or fat Fire Fighting Mediums Type Old Code BS EN 3 Colour Code Fire Class Water Signal Red Signal Red A Foam Cream Red with a Cream panel above the operating instructions A B sometimes E Dry Powder French Blue Red with a Blue panel above the operating instructions A B sometimes C E Carbon Dioxide CO2 Black Red with a Black panel above the operating instructions B E Wet Chemical No F Class Red with a Canary Yellow panel above the operating instructions A F Class D Powder French Blue Red with a Blue panel above the operating instructions D The element covers quite extensively the need for a site fire plan, correct and adequate signage. A detailed fire risk assessment should be carried out and firstly any dangerous items or situations should be eliminated, after which strict control measure as previously described should be implemented along with adequate training for personnel. A culture which encourages operatives to report fires by firstly raising the alarm when a possible fire situation is observed without the risk of ridicule should be embraces. Fire training into the correct procedures to follow in the event of a fire, fire drills, and responsible persons who can verify buy roll call that all people a present. Records should be kept of fire induction training courses where personnel are informed of procedures, records should also be kept of the testing of equipment In the event of a fire If you are properly trained and only if should you When planning for work the fire risk assessment must be prepared alongside all other documents, thought should be given to the escape routes, any work place must have at least two exits, any controlled fires must be extinguished at the end of work, other hazardous equipment such as gas bottles should have the appropriate valves fitted and turned off when not in use.
extinguishers provided but do
not put yourself in danger
way out, so that you can get
out safely
Saturday 5 April 2008
Typical Examination Questions based on Element 6
1. a) Describe b) Outline FOUR factors that may affect the severity of injury from contact with electricity. (4) (4) 2. Outline (8) Measures include: 3. HSG65 Electricity at Work-Safe Working Practices gives guidance on the frequency of inspection for such equipment. State frequencies for the inspection and testing of electrical hand held tools and associate equipment used on a construction site and support your answers with appropriate examples. (8) A hand held tool and equipment should be visually inspected before use, including cables, cord grips, casings and plugs. 230 volt equipment should be tested before first use and then at monthly intervals while a formal weekly inspection is also required. 110 volt equipment should be tested before first use and then at three monthly intervals while a formal monthly inspection is also required. Extension leads should have an initial test before first use followed and then at monthly intervals while a formal weekly inspection is also required 4. List (8) Items on list could include: Equipment appropriate for the task and environment, equipment tested, plugs, connectors and cables free from damage or defect, correct wiring and sound connections, fuses and other means of preventing excess current in place and of correct rating, accessibility and appropriate means of isolation and system not overloaded. 5. In relation to the use of electrical cables and plugs in the workplace: (i) Identify FOUR (ii) Outline (4) (4) Examples include: Failure to select right equipment for the environment (armoured or heat resistant cables may be require). Incorrect rating of fuses. Ineffective or discontinuous earthing. Overload of Socket outlets. Cables unnecessarily long (or too short). The use of coiled extension leads. Poorly wired plugs (wires under tension or outer protective sheath not clamped). The use of defective cables and plugs. (ii) Precautions should have followed automatically from the deficiencies listed in (i)
the possible effects of electricity on the body.
the measures to be taken to minimize the risk of shock from the use of electric hand tools.
the items that should be included on an inspection checklist designed to ensure the safety of portable electrical hand-tools.
examples of faults and bad practice that could contribute to electrical accidents.
the corresponding precautions that should be taken for each of the examples identified in (i).
Element 6 Electrical Hazards and Control
The section of the NCC1 describes what hazards are posed by the presence of electricity on a construction site, the hazards posed by the use of electricity and associated equipment such as hand tools, extension cables, portable and fixed lighting, temporary supplies from mains or generators. The use of electrical hand tools is considered a major hazard on construction sites, therefore there are guidelines on the inspection and record keeping for these tools or equipment. Testing Suggested inspection and test frequencies for electrical equipment on construction sites Equipment/application Voltage User check Formal visual Combined inspection and check Battery operated power tools and torches Less than 25 volt No No No 25V Portable hand lamps 25 volt secondary winding from transformer No No No 50V portable hand lamps Secondary winding centre tapped to earth (25 volt) No No Yearly 110V portable and hand held tools, extension leads, site lighting, movable wiring systems and switchgear Secondary winding centre tapped to earth (50 volt) Weekly Monthly Before first use and then 3 monthly 230V portable and hand held tools, extension leads and portable floodlighting 230 volt mains supply through 30mA RCD Daily/every shift Weekly Before first use and then monthly 230V equipment such as lifts, hoists and fixed floodlighting 230 volt supply fuses or MCBs Weekly Monthly Before first use and then 3 monthly RCDs fixed ** Daily/every shift Weekly * Before first use and then 3 monthly Equipment in site offices 230 volt office equipment Monthly 6 monthly Before first use and then yearly * Note: RCDs need a different range of tests to other portable equipment, and equipment designed to carry out appropriate tests on RCDs need to be used. ** It is recommended that portable RCDs are tested monthly Key points Causes of electric shock Legislation covering the use of electricity on construction sites Working near overhead power lines The local electricity company must be consulted before any work starts and a safe system of work must be devised and implemented. Other suppliers may also need to be consulted, for example, Local Authorities, National Grid and other electricity companies. Special attention should be paid to traffic movements and the erection of appropriate warning sign and barrier (goalposts) should be erected, this apply to the use of excavating machinery near overhead power lines.
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