Detection beyond the Minimum Up to this point we have been reviewing what we must

install to satisfy the ‘minimum’ requirements of the Building Code.

When we wish to provide detection that exceeds the minimum Code requirements, or when dealing with improved protection for the equipment or services for specific hazards such as a plant process or a

telecommunications room, there are a number of factors that must be considered:

• Value of the risk – is the risk an irreplaceable object such as art or

heritage item, or does it provide a service which is extremely important to a business such as a communications room

• Fire source - We must assess the hazard for the type of material that will likely be the fire source, and how it will ignite and burn. For instance in an electrical room or top of elevator shaft where a fire detector is required, provide a smoke detector rather than a heat detector as being far more able to detect the type of expected combustion at a much earlier point in time.

• Burning characteristics - Obviously fires involving flammable liquids ignite, grow and expand differently and far more rapidly than ones starting in a cable tray.

• Actuate extinguishment system - Pre action sprinkler systems, deluge systems and special hazard extinguishment system require

appropriate detection for activation

• Length of time to start suppression – Where automatic suppression is included, extinguishment generally starts almost at the point of detection, while if physical response of building fire services or the remote fire service is required, initiating their response rapidly may, be critical.

• Physical parameters of the space and/or the objects requiring

protection - Consider the room or area, possible obstructions, ceiling heights, air movement, presence of other combustibles, potential device locations, etc. If the hazard is an object or open surface where and how can detection be mounted.

As we have learned previously, fire is a chemical process where materials are consumed releasing particulate matter consisting of smoke particles and soot, as well as producing significant heat. The rate at which these items are released is dependent upon the material being consumed and the surrounding environment.

The fastest and most reliable detection method applicable for one situation is unlikely to be the best suited for other situations. Typically, we are concerned with detecting a fire early in its development when it is small, so that action can be

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taken and the fire extinguished, thus negating the need for evacuation of the building or resulting in significant damage to equipment or its operation.

Hopefully, the water sprinklers will not have to discharge, and the fire department will not have to use their hoses.

By assessing the type of fire signature we are dealing with, together with the manner or rate at which it will burn, we can select the fire detection technology most suited to the risk. In all cases, the faster we can detect a fire and begin the response process, the less is the risk to life safety, and damage to the building and its’ contents.

3.9 Chapter Summary

1. The system designer is directed to use automatic fire detectors in various rooms. The Building Code is the document that contains those instructions.

2. The term ‘fire detector’ includes both heat detectors and smoke detectors.

3. Smoke detectors are considered to be life-saving early-warning devices because they will respond to a fire scenario before a heat detector or a sprinkler.

4. Smoke detectors therefore are required by the Building Code to be installed in rooms of a residential nature such as bedrooms in hospitals and nursing homes as well as some exit corridors and stairwells.

5. Heat detectors, on the other hand, are often required in service rooms such as elevator rooms, electrical rooms and boiler rooms.

6. Heat detectors do not have to be installed if automatic sprinklers are present – as long as the Fire Alarm System monitors the sprinklers.

7. Fire detectors depend upon the movement of air within any detection area for proper detection of a fire. Careful placement of the detectors on the ceiling is very important. Optical flame detectors, on the other hand, are line-of-site devices. Infrared (IR) and ultra violet (UV) detectors will therefore react almost instantly to a naked flame.

8. Acceptable detector ceiling locations are determined by referring to CAN/ULC-S524 Installation of Fire Alarm Systems.

9. Different combustibles produce different by-products including heat and various visible and invisible toxic gasses. Proper selection of detection device is critical to the early detection of a fire condition without the nuisance of false alarms.

10. Remember that the requirements provided in the Code are minimum

requirements. The owner/designer may well opt to install a greater degree of fire safety by going beyond the listed minimums.

3.10 Review Questions

# ? Question Section

3-1 Where sprinklers are installed, alarm flow switches on the sprinkler system are __________________to the Fire Alarm System in order to initiate alarm signals to alert the

occupants and initiate fire service response.

A Mechanically altered B electrically connected C pneumatically supervised

D not connected

3-2 In order for a heat detector to respond to a fire:

A sufficient smoke to satisfy the response characteristic of the detector must reach the detector

B sufficient heat to satisfy the response characteristic of the detector must reach the detector

C sufficient products of combustion to satisfy the response characteristic of the detector must reach the detector

D sufficient time and smoke to satisfy the response characteristic of the detector must reach the detector

3-3 Smoke detectors at the top and intermediate levels in stairwells should be located:

A over areas where high humidity is in the environment B in locations where large amounts of saw dust can ignite the

atmosphere

C over the landings wherever possible and not over the open stair where ladders cannot provide access

D in areas where the temperature reaches minus thirty degree Celsius 3-4 Flame detectors are:

A alarm flow switch devices B a type of smoke detector C a line-of-site device

D required in all building transformer rooms

# ? Question Section

3-5 A combined smoke sensor and audible alarm device designed to sound an alarm within a room or suite in which it is

located, upon the detection of smoke within that room or suite is identified as:

A Smoke detector

B Heat detector

C Smoke Alarm

D Air Sampling Type Detector

3-6 Building Code specifies only the _____________

requirements,

A minimum

B maximum

C local authority D municipal specific

3-7 Heat detectors need not be installed where the floor area is A sprinklered, and the sprinklers are monitored by the Fire Alarm

System.

B heated, and the floor temperature is monitored by the Fire Alarm System.

C not occupied, and the presence of occupants are monitored by the Fire Alarm System.

D An assembly area and the storage rooms are not sprinklered.

3-8 Smoke detectors required in sleeping rooms of a care or detention occupancy:

A shall upon activation provide evacuate the entire facility immediately

B shall upon activation provide an audible and visual indication to staff serving those rooms.

C shall only send for the emergency response team D shall remain silent so not to worry the patients

3-9 By assessing the type of fire signature we are dealing with, together with the manner or rate at which it will burn, we can select the fire detection technology most suited to the risk.

A True

B False

# ? Question Section

3-10 When we consider the selection of a fire detection

technology to be used and the density and location of the fire detectors, we generally are looking

A how much does it cost as the primary concern

B at how long it will take to detect a given fire scenario

C how does it look in the environment as the primary concern D at how long it will last following a fire condition