Showing posts with label Water Extinguishers. Show all posts
Showing posts with label Water Extinguishers. Show all posts

Sunday, March 25, 2018

Fire safety in under construction site a short note

Fire safety in under construction site a short note
General Fire
What you need to do

Although the construction industry’s performance has improved over the past decade, the rates of death, serious injury and ill health for construction site workers are still too high. When construction activities are not adequately controlled, children and other members of the public can also be killed or injured, and property adjacent to construction sites be put at risk – for example, from a site fire large enough to spread off-site. The responsible person will usually be the main or principal contractor in control of the site.

You should identify sources of fuel and ignition and establish general fire precautions including, means of escape, warning and fighting fire, based on your fire risk assessment.
In occupied buildings such as offices, make sure the work does not interfere with existing escape routes from the building, or any fire separation, alarms, dry risers, or sprinkler systems.
Key issues are:
·        Risk assessment
·        Means of escape
·        Means of giving warning
·        Means of fighting fire
Construction of timber frame buildings will require significant additional measures – please refer to the specific guidance listed.


What you need to know
Each year there a number of serious fires on construction sites and buildings undergoing refurbishment.

Risk assessment
In most cases, conducting a risk assessment will be a relatively straightforward and simple task that may be carried out by the responsible person, or a person they nominate, such as a consultant.
There are five steps in carrying out a fire risk assessment:
1.     Identify hazards: consider how a fire could start and what could burn;
2.     People at risk: employees, contractors, visitors and anyone who is vulnerable, eg disabled;
3.     Evaluation and action: consider the hazards and people identified in 1 and 2 and act to remove and reduce risk to protect people and premises;
4.     Record, plan and train: keep a record of the risks and action taken. Make a clear plan for fire safety and ensure that people understand what they need to do in the event of a fire; and
5.     Review: your assessment regularly and check it takes account of any changes on site.

Means of escape
Key aspects to providing safe means of escape on construction sites include:
·        Routes: your risk assessment should determine the escape routes required, which must be kept available and unobstructed;
·        Alternatives:well-separated alternative ways to ground level should be provided where possible;
·        Protection: routes can be protected by installing permanent fire separation and fire doors as soon as possible;
·        Assembly: make sure escape routes give access to a safe place where people can assemble and be accounted for. On a small site the pavement outside may be adequate; and
·        Signs: will be needed if people are not familiar with the escape routes. Lighting should be provided for enclosed escape routes and emergency lighting may be required.

Means of giving warning
Set up a system to alert people on site. This may be temporary or permanent mains operated fire alarm (tested regularly), a klaxon, an air horn or a whistle, depending on the size and complexity of the site.

The warning needs to be distinctive, audible above other noise and recognizable by everyone.
Means of fighting fire
Fire extinguishers should be located at identified fire points around the site. The extinguishers should be appropriate to the nature of the potential fire:
·        wood, paper and cloth – water extinguisher;
·        flammable liquids – dry powder or foam extinguisher;
·        electrical – carbon dioxide (C02) extinguisher.
·        Nominated people should be trained in how to use extinguishers.

Process fire risks
What you need to do
The fire risk from site activities must be assessed and precautions taken to control:
·    Combustible material – the quantity of combustible materials on site should be kept to the minimum and all such materials safely stored and used.
·        Ignition sources – action is needed to eliminate, reduce and control ignition sources on site.
Construction of timber frame buildings will require significant additional measures to those outlined here. You should refer to the specific guidance listed in Resources, below.
What you need to know
Each year there are a number of serious fires on construction sites and buildings undergoing refurbishment. Many could be avoided by careful planning and control of work activities.
Any outbreak of fire threatens the safety of those on site and will be costly in damage and delay. It can also be a hazard to people in surrounding properties.
Fire can be a particular hazard in refurbishment work when there is a lot of dry timber and at the later stages of building jobs where flammable materials such as adhesives, insulating materials and soft furnishings are present
Combustible material
Many solids, liquids and gases can catch fire and burn. It only takes a source of ignition, which may be a small flame or an electrical spark, together with air. Preventive actions that can be taken include:
1.     Quantity: fire risk can be reduced by controlling the amount of combustible material in the work area until it is needed;
2.     Flammability: it may be possible to specify materials that are less combustible. Remember that when worked on, materials may become more easily ignited eg solids turned to dust or crumb;
3.     Storage: combustible materials should ideally be stored outside buildings under construction, especially volatile materials eg LPG. Internal storage must be planned and located where it will not put workers at risk;
4.     Rubbish: good housekeeping and site tidiness are important to prevent fire and to ensure that emergency routes do not become obstructed;
5.     Volatile flammable materials: extra precautions are needed for flammable liquids, gases and oxygen cylinders especially when internally stored;
6.     Coverings and sheeting: protective coverings and scaffold sheeting may add to fire risk. This can be reduced by use of flame retardant materials;
7.     LPG: liquefied petroleum gas (LPG) is widely used in construction eg in connection with bitumen boilers and site accommodation. LPG has been involved in many serious fires and explosions, particularly where there have been leaks in confined areas. Strict precautions are required where LPG is stored and used; and
8.     Tanks and services: demolition projects can involve an increased risk of fire and explosion. Dismantling of tank structures may cause ignition of flammable residues or disruption and ignition of buried gas services.

Ignition sources
It is important that you take action to control ignition sources including:
Hot work: all hot work generating heat, sparks or flame can cause a fire. Precautions include:
·        clearing the area of combustible materials;
·        suitable fire extinguishers; and
·        maintaining a careful watch throughout the work.
·        a permit to work (PTW) system can help manage the risk on larger projects.
Plant and equipment: select electrical and engine driven plant of suitable capacity to prevent overheating. Fasten lamps to a solid backing and, if mounted on tripods, make sure the tripod is stable. Electrical equipment in flammable atmospheres must be suitable for the nature and extent of the flammable atmosphere;
Smoking: bring the rules on smoking to the attention of all workers and visitors to the site and enforce them;
Electrical installationsshould be of sufficient capacity for the intended use and designed, installed, inspected and maintained by competent people;
Bonfiresshould not normally be allowed on site. There should be alternative arrangements for the proper disposal of rubbish and waste;
Arsonmeasures should be in place to prevent unauthorised site access. Sites with high fire loading or a history of vandalism and arson may need additional measures eg lighting, out-of-hours security or CCTV.


Thanks for reading, and as always, stay safe.

Saturday, June 1, 2013

Pros and Cons of Fire Extinguisher types

Pros and Cons of Fire Extinguisher types

Classes of fire
Fires are classified according to the materials that are burning. This classification system allows you to choose the right fire extinguisher.

Fire is broken down into Six Classes – A, B, C, D, E and F.
Types of extinguisher
·        Foam
·        ABC Powder
·        Carbon Dioxide (CO2)
·        Wet chemical
·        Powder
·       Monnex
Foam – Suitable for Class A and B Fires
Class A – combustible solids (paper, wood)
Class B – flammable liquids (petrol, diesel, spirits, paint)
Pros
Higher A rating than water, so more effective on combustible solids. For example, a 6lt Foam has the extinguishing capability of a 9lt Water.
Foam discharge is easier to clean up than powder.
Foam is not as conductive as water, so it won’t cause as much damage if sprayed on electrical equipment.
Cons
It can be susceptible to frost.

ABC Powder – Suitable for Class A, B, C and Electrical Fires
Class A – combustible solids (paper, wood)
Class B – flammable liquids (petrol, diesel, spirits, paint)
Class C – flammable gases (methane, butane
Pros
Ideal as a multipurpose extinguisher for home and work.
Twice as effective as Foam on Class A fires, for example: a 6kg Powder is rated 27A, whereas a 6lt Foam is rated 13A.
Not as susceptible to frost as water-based extinguishers.
Very effective for burning and free-flowing liquids.
When powder is applied to hot smouldering surfaces, the particles fuse together and swell. This forms a barrier which excludes oxygen and prevents reigniting.
Cons
Can be messy, as it’s a fine powder. Clean up can be costly and time-consuming, so consideration should be given where misuse/accidental use would be an issue.
Reduces visibility when discharged, so consideration required when placing near escape routes, stairwells, etc.
May aggravate respiratory conditions when discharged.
Limited cooling properties.
While Powder is safe for use on electrical fires, it can cause corrosion.

CO2 – Suitable for Class B and Electrical Fires
Class B – flammable liquids (petrol, diesel, spirits, paint)
Pros
Smothers fire quickly in draught-free conditions.
A non-conductor, so can be used on live electrical equipment.
Leaves no residue and is not as damaging to electrical equipment as powder.
Cons
It’s an asphyxiate, so care should be exercised when using in confined spaces.
Limited cooling properties and no protection against reigniting.
A non-insulated horn can cause frost burn if user accidentally touches the horn when in use.  Frost- free horns offer some protection against this (a frost free horn has a honeycomb ring on the internal lining; non-insulated horns have a single layer of plastic).

Wet Chemical – Suitable for Class F Fires
Class F – cooking oils and fats

Powder – Suitable for Class D Fires
Class D – metals
Specialist Class D Dry Powder for Flammable Metals.

Monnex – Suitable for Class B and C Fires
Class A – combustible solids (paper, wood)
Class B – flammable liquids (petrol, diesel, spirits, paint)
Pros
High performance specialist powder extinguisher.
Also safe to use on flammable chemicals.
Ideal for garages, fuel depots, airports, motor racing events and chemical stores.

Automatic Extinguisher
Dry powder extinguisher ideal for use on oil or gas burners. Heat activated. No manual intervention required.

Water Extinguishers
Water has excellent cooling properties but is only suitable for use on Class A fires. Foam is often the preferred option, as it is suitable for both Class A and B and has a better A rating.

Halon
Under the European Council Regulation 2037/2000, Halon portable fire extinguishers are no longer permitted for use in the European Union due to their ozone-depleting substances. Exceptions include use in civil aircraft, the armed forces and the emergency services.
Class F – cooking oils and fats

Fire rating system

Fire rating refers to a fire extinguisher’s fire-fighting capabilities.
Although fire is categorised into 5 classes, only classes A, B and F carry a fire rating.
You will find the rating printed on the body of the extinguisher – for example: 13A/75F.
In this example, the prefix numbers 13 and 75 refer to the size of the fire and the letters A and F represent the Class of Fire on which to use the extinguisher.
The higher the prefix number the greater the fire extinguisher’s fire-fighting capabilities.
In this instance, the extinguisher is suitable on a Size 13 Class A (Combustible Solids) fire and also on a Size 75 Class F (Cooking Oils & Fats) fire.

In Class A the size refers to 13 metres in length, while in classes B and F the 75 represents volume in litres.