Fire protection

From Wikipedia, the free encyclopedia

Fire protection is the safety and of the hazards associated with fires. It involves the study of the behaviour, compartmentalisation, suppression and investigation of fire and its related emergencies as well as the research and development, production, testing and application of mitigating systems. In structures, be they land-based, offshore or even ships, the owners and operators are responsible to maintain their facilities in accordance with a design-basis that is rooted in laws, including the local building code and fire code, which are enforced by the Authority Having Jurisdiction. Buildings must be constructed in accordance with the version of the building code that is in effect when an application for a building permit is made. Building inspectors check on compliance of a building under construction with the building code. Once construction is complete, a building must be maintained in accordance with the current fire code, which is enforced by the fire prevention officers of a local fire department. In the event of fire emergencies, Firefighters, fire investigators, and other fire prevention personnel called to mitigate, investigate and learn from the damage of a fire. Lessons learned from fires are applied to the authoring of both building codes and fire codes.

In the United States, this term is used by engineers and code officials when referring only to active and passive fire protection systems, and does usually not encompass fire detection systems such as fire alarms or smoke detection.

Contents

[edit] Goals

Fire protection has three major goals:

  • Life safety - the minimum standard used in fire and building codes.
  • Property protection - on a public scale, this is intended to prevent area wide conflagrations. At an individual building level, this is typically an insurance consideration (e.g., a requirement for financing), or a regulatory requirement.
  • Continuity of operations - on a public scale, this is intended to prevent the interruption of critical services necessary for the public welfare (e.g., a 911 emergency call center). To a private owner, this is typically not a regulatory issue, but is self-motivated, sometimes partially due to fire insurance considerations. Interruption of operations due to fire damage can be very costly. For instance, the lost revenue to a power company if a nuclear reactor is shut down due to a fire may cost about one million US dollars per day.

[edit] Classifying fires

When deciding on what fire protection is appropriate for any given situation, it is important to assess the types of fire hazard that may be faced.

Some jurisdictions operate systems of classifying fires using code letters. Whilst these may agree on some classifications, they also vary. Below is a table showing the standard operated in Europe and Australasia against the system used in the United States.

Type of Fire Australasian European United States
Fires that involve flammable solids such as wood, cloth, rubber, paper, and some types of plastics. Class A Class A Class A
Fires that involve flammable liquids or liquifiable solids such as petrol/gasoline, oil, paint, some waxes & plastics, but not cooking fats or oils Class B Class B Class B
Fires that involve flammable gases, such as natural gas, hydrogen, propane, butane Class C Class C
Fires that involve combustible metals, such as sodium, magnesium, and potassium Class D Class D Class D
Fires that involve any of the materials found in Class A and B fires, but with the introduction of an electrical appliances, wiring, or other electrically energized objects in the vicinity of the fire, with a resultant electrical shock risk if a conductive agent is used to control the fire Class E (Class E) now no longer in the European standards Class C
Fires involving cooking fats and oils. The high temperature of the oils when on fire far exceeds that of other flammable liquids making normal extinguishing agents ineffective. Class F Class F Class K

Fires are sometimes categorized as "one alarm", "two alarm", "three alarm" (or higher) fires. There is no standard definition for what this means quantifiably, though it always refers to the level response by the local authorities. In some cities, the numeric rating refers to the number of fire stations that have been summoned to the fire. In others, the number counts the number of "dispatches" for additional personnel and equipment.[1][2]

[edit] Components

Structural fire protection (in land-based buildings, offshore construction or onboard ships) is typically achieved via three means:

  • Passive fire protection (use of integral, fire-resistance rated wall and floor assemblies that are used to form fire compartments intended to limit the spread of fire, or occupancy separations, or firewalls, to keep fires, high temperatures and flue gases within the fire compartment of origin, thus enabling firefighting and evacuation)
  • Active fire protection (manual and automatic detection and suppression of fires, as in using and installing a Fire Sprinkler system or finding the fire (Fire alarm) and/or extinguishing it)
  • Education (ensuring that building owners and operators have copies and a working understanding of the applicable building and fire codes, having a purpose-designed fire safety plan and ensuring that building occupants, operators and emergency personnel know the building, its means of Active fire protection and Passive fire protection, its weak spots and strengths to ensure the highest possible level of safety)

[edit] Balanced Approach

Passive fire protection (PFP) in the form of compartmentalisation was developed prior to the widespread use of active fire protection (AFP), mainly in the form of fire sprinklers. During this time, PFP was the dominant mode of protection provided in facility designs. With the widespread installation of fire sprinklers in the past 50 years, the reliance on PFP as the only approach was reduced. There is a perception by some fire protection engineers and some members of the fire protection construction industry that the model building codes have changed with too much reliance on AFP.

Lobby groups are typically divided into two camps favouring active or passive fire protection. Each camp tries to garner more business for itself through its influence in establishing or changing local and national building and fire codes. At present, the camp favouring AFP appears to be leading.

A balanced approach between all three parts, Education, AFP and PFP, is generally recognised to be the best overall approach, but there are disagreements in emphasis. This is to be expected, considering that many of the proponents of one camp or another have a vested interest in the outcome, as they are involved in the sales or construction of one of the systems. Many insiders in the trade, who know how much field conditions can influence matters, conclude that no one side has all the answers.

The relatively recent inclusion of performance based or objective based codes tend to support AFP initiatives, and can lead to the justification for less substantial construction. Some proponents of PFP feel that this new approach is not properly balanced, as the use of automatic suppression with codes allowing performance based designs often favours the cost savings resulting from less solid structures. At times it works the other way around, as firewalls that protrude through the roof structure are used to "sub-divide" buildings such that the separated parts do not require sprinklers.

The decision to favour AFP versus PFP in the design of a new building may be affected by the lifecycle costs. Lifecycle costs can be shifted from capital to operational budgets and vice versa. AFP, may initially require less capital to install, but due to its nature requires significant operational resources to maintain. PFP on the other hand, may be more costly to install but less costly to maintain. Planners consider the expected life expectancy of a building to make the most beneficial long term decision.

[edit] Common items to check for to avoid systemic problems

In compliance with the local building code and fire code, the architect and his other consultants typically outline the basic fire protection plan for a building. When applications for a building permit are made, this plan then becomes known to the Authority Having Jurisdiction (AHJ). If accepted by the AHJ, a permit is issued. Deviations from that original plan, should be made known to the AHJ to make sure that the change is still in compliance with the law. For existing buildings, this means that changes are to be approved through the permit regime, even though the structure already exists. The City of Toronto, for instance, publishes a list of items to tell interested parties when a permit is required. Toronto also indicates when a permit is not required. The idea behind this is to catch and prevent any unsafe conditions that may violate the law and put people at risk. For fire protection, this means that if any one of the three components of Fire Protection fail, the fire safety plan can be immediately and severely compromised. Examples of code violations can be seen here. For example, if the firestop systems in a structure were inoperable, a significant part of the fire safety plan would not work in the event of a fire because the walls and floors that contain the firestops are intended to have a fire-resistance rating, which has been achieved through passing a fire test and, often, product certification of the components involved in the construction of those walls and floors. It is a physical impossibility to pass a fire test, that demands that the wall or floor in question not permit the passage of fire, when there is a hole in it to let the fire through or when that hole develops before the fire-resistance duration period for the subject barrier is elapsed. Therefore, an improperly sealed or an unsealed penetration such as this removes the rating of the wall or floor it is in. If that wall or floor performs a structural function as well as forming part of an area of refuge, for instance, it is easy to see why this violation can have a cumulative effect, which is why municipalities use the permit process and on-site inspections to minimise the risk to the public. Since the overall plan depends on all pieces, it is important to see that each item is in fact functional. Likewise, if there were a sprinkler system or an alarm system, but it's down for lack of knowledgeable maintenance, or if building occupants prop open a fire door and then run a carpet through, the likelihood of damage and casualties is markedly increased. It is vital for everyone to realise that fire protection within a structure is a system that relies on all of its components.

There are many things that can and often do go wrong prior to and during the construction of a building. What happens afterwards, however, can also be substantially hazardous, to the point of entirely defeating the fire protection plan that was put in place during the design-phase of a building. The City of Madison, for instance, publishes the most common fire code violations found in its jurisdiction.

Other common operator errors include, but are not limited to, the following:

Any changes that affect the overall fire protection plan, however small they may appear to the layman, legally require the owner to either gain the approval of the fire prevention officer at the municipal fire department or to apply for a building permit with the local, municipal building department. The permit fee is intended to cover the time and expenses for the Authority Having Jurisdiction to evaluate the contemplated change against applicable code requirements. Failure to obtain such approvals make the owner vulnerable to charges of negligence and culpability in a court of law.

[edit] Questions for inspectors

The need for maintenance to avoid code violations is apparent. It was described recently in in this article. To clarify, the following two questions can be used as a litmus test for a building, offshore construction or ship owner's degree of due diligence:

The idea behind this is that if one does not have an inventory of the firestops nor knowledge of certification listings, it is physically impossible to prove compliance.
The correct response is the precise number of firestops and a reference to a set of drawings that shows each one with a number and hyperlink or paper reference to the certification listings upon which each installed configuration is based. Otherwise, one may walk up to a firestop, see, for instance, a red material. Red firestops are made by more than one manufacturer, each of which have a multitude of certification listings. How does one perform a proper repair without that knowledge? It is not possible to prove compliance without those documents.
  • "Where is your local copy of the current fire code and the construction code(s) that were in effect when you applied for the permit(s)."

The idea behind this is that if one operates a building and does not have a copy of the code that one is legally obliged to follow, it becomes impossible for the owner to be able to demonstrate compliance with a document he or she does not have.

The correct response is: "Here they are, copies of both the fire code and the building code."

The former question tests the owner's knowledge of his or her structure's fire protection and continued compliance with the code by bringing up the example of a common deficiency: the firestopping of existing and new openings in wall and/or floor assemblies required to have a fire-resistance rating. Answers to the latter question expose an owner's ability to keep the fire protection system set up correctly under normal operations and remedial work. The documents are necessary as nobody (including members of an Authority Having Jurisdiction), can be expected to know an entire code by heart. Both fire codes and building codes will refer to one another (to avoid duplication of text).

Examples for remedial work are plumbing work (a new toilet for instance, which could cause the need for a dozen new firestops to be made and breaches of fire barriers), electrical work (say a new receptacle in a wall, which necessitates a conduit and cable), new doors, changing the use of a room, etc.

These materials need to be known by the operators and staff of the building as any routine, seemingly small act, can defeat the overall fire protection plan, which forms the design basis for the building. For example, the installation of a piece of equipment in the building such as a water pump. Depending on where this is installed, it could be construed as a change in occupancy, which in turn requires a building permit to ensure compliance with regulations. Likewise, added piping or cable to run the equipment might necessitate the breaching of a fire-resistance rated wall or floor, where now a firestop is required, which would also necessitate a building permit. If no application for a building permit is made, the Authority Having Jurisdiction is unaware of the change and if the change is not immediately apparent to a fire prevention officer, nobody is the wiser but the owner is culpable.

It is important to remember that even when a fire prevention officer who conducts an inspection does not find anything amiss, this does not mean that the building is in full compliance with the fire code. There is a limit to the amount of searching and disturbing that a fire prevention officer is legally allowed, financed by the municipality, and able to do. For instance, an inspector may only be given one hour to inspect a school, which would not be enough time for an in-depth check. An inspector may be limited to a quick check on fire extinguishers and maintenance records of the sprinkler system. The written OK given after an inspection is only an "OK" for the parts inspected, which may not include things overlooked which severely breach the code. A passed inspection does not absolve a building owner of his or her responsibility to maintain the entire facility in compliance with the fire code, nor does it give them carte blanche that everything is OK with the Authority Having Jurisdiction.

[edit] See also

[edit] External links

Wikimedia Commons has media related to:
v • d • e
Major fields of technology
Applied science
Information
Industry
Military
Domestic
Engineering
Health and safety
Transport