Sprinklers in Lieu of Fire Detectors

[sunyaer]

This is from Ontario Building Code Division B:
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3.2.4.16. Sprinklers in Lieu of Fire Detectors

(1) Fire detectors required by Article 3.2.4.11. and heat detectors required by Sentence 3.2.4.12.(2) need not be provided within a floor area if the floor area is sprinklered and the sprinkler system is electrically supervised in conformance with Sentence 3.2.4.10.(3). (See Appendix A.)

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My question is:

1. Is a sprinkler system not always required to be provided with fire or heat detectors?

2. Does a sprinkler system without fire / heat detectors that is electrically supervised have more advantages than a sprinkler system with fire / heat detectors that is not electrically supervised?

3. In simple word, does "electrically supervised" mean there is staff supervising the system 24/7?

 

[sunyaer]

Think about the clause again, besides those questions asked above, this question came up to my head:

Is an electrically supervised sprinkler system more cost effective than fire / heat detectors? If not, why use a sprinkler system in lieu of fire / heat detectors?

 

[ICE]

If not, why use a sprinkler system in lieu of fire / heat detectors?

One attempts to put the fire out…the other lets you know that it’s burning. People generally install a sprinkler system only when required to do so.

 

[bill1952]

The answers to your questions depend on what sprinkler standard the OBC references. Here is some background if using NFPA 13.

Sprinkler Supervision: What Does it Mean? | NFPA

Automatic Sprinklers have proven to be highly effective over the years. Recent statistics show that sprinklers operated 92% of the time in fires that were considered large enough to activate sprinklers. The leading cause of sprinklers failing to operate is because the sprinkler system had been...

www.nfpa.org

 

[tmurray]

This is from Ontario Building Code Division B:
_________________________________________________________________________________________________________________________________________________________________________________

3.2.4.16. Sprinklers in Lieu of Fire Detectors

(1) Fire detectors required by Article 3.2.4.11. and heat detectors required by Sentence 3.2.4.12.(2) need not be provided within a floor area if the floor area is sprinklered and the sprinkler system is electrically supervised in conformance with Sentence 3.2.4.10.(3). (See Appendix A.)

________________________________________________________________________________________________________________________________________________________________________________

My question is:

1. Is a sprinkler system not always required to be provided with fire or heat detectors?

2. Does a sprinkler system without fire / heat detectors that is electrically supervised have more advantages than a sprinkler system with fire / heat detectors that is not electrically supervised?

3. In simple word, does "electrically supervised" mean there is staff supervising the system 24/7?

The concept that the code is getting at is that as soon as a sprinkler system is electronically supervised, a sprinkler head IS a heat detector. Most sprinklers only discharge when heat causes a bubble to expand and break a glass container in the sprinkler. Typically, when fire starts and it grows large enough to activate a sprinkler, only that sprinkler activates. If the fire continues to grow, it can activate other sprinklers in the same way. There is a large percentage of fires where only 1-2 sprinkler heads activate.

So, Sprinkler head activates and starts discharging water, water moving through the system is registered by the flow valve. The flow valve is one of the parts that is electronically supervised, so when water starts to flow in the system, it reports this back to the fire alarm system. The fire alarm system now knows that there is an emergency in the building and sounds the fire alarm.

1. It would be very rare, but not always. There are a couple of exemptions where the installation of a sprinkler system would not trigger a fire alarm installation, so you could have sprinklers installed without a fire alarm.

2. Just cost of installation. There are times where despite the relaxation in the code, designers will continue to specify the installation of detection systems. Normally, it is where the discharge of a sprinkler system would be catastrophic. They would usually install really expensive air sampling systems that can detect fire at the earliest stages, sometimes thermal cameras, etc. Think about national art galleries and museums. We don't want to know there is a fire when it is big enough to cause the sprinkler to discharge, we want to know about it way before then and hopefully avoid the sprinkler discharging altogether.

3. "electrically supervised" simply means the sprinkler system is connected to the fire alarm system. This connection happens in multiple ways, the flow valve we previously discussed, but all valves are supervised to make sure none are turned off (this typically causes a "supervisory" alert on the fire alarm panel - "annunciator").

Sprinkler systems are more costly to install and maintain than heat detection.

 

[sunyaer]

...
1. It would be very rare, but not always. There are a couple of exemptions where the installation of a sprinkler system would not trigger a fire alarm installation, so you could have sprinklers installed without a fire alarm.
...

Is there a real example of these exemptions?

 

[tmurray]

Is there a real example of these exemptions?

Actually, I was just looking in the OBC, and they appear to have amended out the trigger that when a sprinkler system is installed, a fire alarm must be installed. Here are the requirements from the NBC.

1) Except as permitted in Sentences (2) and (3), a fire alarm system shall be
installed in buildings in which an automatic sprinkler system is installed.
2) Buildings in which a sprinkler system is installed in accordance with NFPA 13D,
“Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings
and Manufactured Homes,” need not comply with Sentence (1).
3) Buildings that contain fewer than 9 sprinklers conforming to Sentence 3.2.5.12.(4)
need not comply with Sentence (1).

(2) is kind of self-explanatory
(3) a good example would be a room for the storage of refuse. It needs sprinklers per code, but the whole building may not. In that case, a fire alarm would not be required based solely on sprinklering that room.

 

[sunyaer]

...

3. "electrically supervised" simply means the sprinkler system is connected to the fire alarm system. This connection happens in multiple ways, the flow valve we previously discussed, but all valves are supervised to make sure none are turned off (this typically causes a "supervisory" alert on the fire alarm panel - "annunciator").

...

Is "electrically supervised" required to have staff 24/7 involvement of monitoring?