Water-based Extinguishment Systems (Fire Sprinklers)
 

INTRODUCTION

Fire sprinklers play an important role in minimizing the damage caused by fire and, more importantly, have been responsible for saving many lives.  Many municipalities in the Lower Mainland make their installation mandatory, for this very reason.  The layout and design, the installation, and the components that comprise a modern fire sprinkler system represent a unique partnership that spans the various manufacturers, trained fitters, engineers, local and provincial governments, and ULC.  Fire sprinklers are often considered an essential component in assessing an insurance underwriter’s risk and their absence may result in increased premiums for the building owner or occupant.

Ceiling Mounted Pendant Sprinkler (Typical)The most familiar object in any sprinklered building is the sprinkler head.  There are several different types of sprinklers, all of which have different applications and installation configurations.  Most sprinkler heads are of similar construction and comprise four basic parts:  the nozzle, the deflector (with a supporting frame), a plug, and a liquid filled glass bulb (or metallic fusible link).  When a sprinkler activates (the official terminology when this occurs is called fusing) water squirting from the nozzle impinges on the deflector which  converts the stream into a mist of fine droplets that spreads over an area on the ground.Discharging Sprinkler Head  Heat from the fire will flash some of the water mist into steam, which serves to accomplish two things:  it robs the fire of oxygen (steam is much heavier than air), and it cools the area.  Oxygen and heat are two sides of the fire triangle (the third is fuel).  If you remove just one side, the fire will extinguish.  Removing two sides is what makes fire sprinklers such an effective means of combating a fire.  Couple this to the fact that the typical head will activate long before the room temperature becomes untenable would suggest that you shouldn’t consider living in a house without a sprinkler system.

 

 

 

FIRE  SPRINKLER 101

Let’s take a tour of a typical sprinklered building, and examine the testing and inspection requirements in NFPA 25 (2008) (the Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems).

The first stop on our tour is the sprinkler room.  This is a heated centrally located room (or area) in your building which is dominated by some rather large water shut-off valves and lots of various sizes of black pipe.  You’ll find a variety of gauges, test and drain valves, and electrically wired flow and tamper switches.  On some older systems, you’ll often find piping leading outside to a water motor gong (which activates whenever a flow is initiated) as well as to the building’s fire department connection (sometimes called a Siamese connection).  You’ll also find a small red box which contains a number of spare sprinkler heads and a special head removal wrench.  Some sprinkler rooms also contain a small air compressor which is used to pressurize sprinkler lines in unheated spaces (like a parkade or storage locker).  An air pressure gauge must always be installed in these types of systems.  All modern sprinkler systems also employ something called a cross-connection control or back-flow preventer.  This unit stops water in the sprinkler lines from leaching contaminates into, and fouling, the building’s domestic water supply.  It has a series of test valves located along the top or sides (depending on whether the unit is vertically, or horizontally mounted) with electrically supervised water shut-off valves on both ends (the inlet and the outlet).

So, let’s venture out into the common areas of your building.

You’ll likely notice that three different types of sprinkler heads are employed in your system (spare units of each type must be provided in the little red box we mentioned earlier).  A sidewall head is designed to mount on a wall at a specific height from the floor.  You’ll often see these types of heads installed on either side of a glass fire partition wall in a parkade.  You’ll notice that there’s a head mounted on both sides of the glass to form a water curtain if a fire should occur that’s hot enough to  fuse the heads.  This helps ensure the glass wall will function as a fire partition for the time required by the Building Code.

An upright head is mounted with the round metal deflector positioned upper most.  The deflector has angled tines around its circumference that give the installed assembly the look of a small metal mushroom.  Properly installed, the deflector’s support frame should be aligned so that it’s parallel to the supply line (or branch) it’s mounted on, not at right angles.  There is a reason for this.  Because the head is mounted ABOVE the supply line, the pipe masks a good portion of the spray pattern.  The support frame also happens to act as a mask to the potential water discharge when the sprinkler fuses.  Best performance of this type of sprinkler head is assured when both the support frame and branch line are in the correct alignment configuration.

The pendant head is what you would see mounted in a typical ceiling.  Some pendants are hidden by metal covers that blend with the ceiling finish.  This is called a concealed head.

Now that we have the basics covered let’s take a look at the two different types of fire sprinkler systems.

The wet system is the most prevalent in use today.  It’s primarily used indoors in buildings and homes around the world.  And as the name suggests, the system is maintained in a wet condition (fully charged with water) from the local mains supply.  What most insurance companies considered the main drawback of homes with installed sprinkler systems is that if you accidentally trigger a head, water will instantaneously discharge.  This used to be a huge factor in determining whether-or-not you even qualified for insurance (or required a special exclusion which limited their liability in the even the sprinkler system accidentally discharged).  But then organizations like NFPA and CASA (in Canada) commissioned extensive studies into sprinkler related accidents and the real benefits of actually having a fire sprinkler system (i.e. reducing physical property loss in a fire and saving lives) was made manifest.  These days, it’s rare for an insurance company to shy away from a fully sprinklered building.  In fact, you may find yourself paying MORE for insurance if your building ISN’T protected.

The dry system is utilized where low or freezing temperatures are encountered (i.e. unheated building parkades and areas which may be exposed to the elements such as building overhangs or carports).  The water one would normally expect to fill the supply lines is actually replaced with air under pressure maintained by a small compressor located in the water or sprinkler room.  The air pressure secures the top half of a valve clapper housed in a large dome-like structure normally located right above a manual shut-off valve.  When the air is evacuated (as would be the case if a sprinkler in the system were to fuse), the water pressure under the clapper will eventually exceed the downward force of the air holding it closed.  Water then floods the system and will eventually discharge from the activated sprinkler.
 

 

 

 

SPECIAL PROTECTION SYSTEMS

Then there’s some special applications (there are more than the two we happen to mention here, but we won’t be going into that much detail here).  Suffice it to say, if you have any questions about your sprinkler system please feel free to Contact Us!

A Kitchen Fire Suppression System operates on a very similar principal to a fire sprinkler system, the main difference being that instead of water, the nozzles discharge a special water based chemical mixture which is largely made up of potassium carbonate (known in the industry as Karbaloy).  This is stored in sealed pressurized cylinders of various sizes (depending on the area coverage required by the kitchen hood and the types of cooking appliances).  The discharge nozzles employ small plastic or foil end caps to keep cooking activities from clogging them.  Unlike a sprinkler head, the nozzles themselves don’t have a role in detecting a fire, though.  This is accomplished by carefully positioned fusible links kept under tension by a cable attached to the agent storage cylinder’s releasing head.  When the fire’s hot enough to melt the link, the cable releases the extinguishing agent in a single long burst through all of the discharge nozzles at once.  The trip cable also releases a special valve which shuts off the gas supply and activates a series of switches to control hood fan functions and activate the building’s fire alarm system.

Deluge Type Systems are engineered to maximize agent discharge over a large area in cases where special hazards exist that may quickly overcome the functional limits of a normal sprinkler system (note the function of  this type of system is often erroneously portrayed in Hollywood disaster pictures as what you would get when a standard sprinkler head is fused).  Deluge type systems employ open type sprinkler nozzles and are actuated by a separate fire detection means that often involves a two-step process (one step being electronic while the other step is mechanical).  Additionally, other types of extinguishing agents may be employed in lieu of water.  Carbon dioxide, FM-200, Halon, Halotron, FOAM, etc.

The professionals at Anubis Systems Technologies possess both the knowledge and experience in servicing, maintaining, and testing a variety of suppression systems.  And remember, you’re under no obligation to contract our services when you call us to survey your site.  We will give you an honest, straight forward appraisal and make some recommendations to help you get the most out of your building’s fire protection systems.

For more information you can email us or telephone (778) 863-7147.

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SUPPRESSION  SYSTEM  FAQ

I have a sprinkler system installed in my home.  Does it require maintenance or testing?

In a recent article published to the NFPA Fire Sprinkler Initiative News (we’re posting the video separately below), the simple testing procedures outlined in the accompanying video should be followed to the letter.  What the article misses mentioning however, is the required testing of the back-flow preventer.  Chances are you’ll have two installed.  One for the fire sprinkler system and the other for your automatic lawn sprinklers.  BOTH need to be tested by qualified personnel and the test report will likely have to be filed with your local jurisdictional authority (Water Board).  It’s also a good idea to have the sprinkler system drained and the water tested for bacteria or other potentially corrosive contaminants.

A FEW CAUTIONARY NOTES!

  1. On some of these older systems a separate valve was installed for the home sprinkler system.  Make sure this is ON and secured with a chain lock to make sure it’s not inadvertently closed and forgotten about.
  2. If you have never had your home sprinkler checked out, please ensure that you contact a qualified professional to do so as soon as possible.  A number of sprinkler heads have recently been the subject of mandatory recalls and if your home happens to be equipped with an affected unit, it may NOT FUNCTION properly when you need it to.  It may, in fact, MALFUNCTION at some point.
  3. The flow switch depicted in the video is also likely present and interconnected to your home’s smoke alarms.  It is extremely important to ensure that you confirm the operating voltage of the interconnection before you replace smoke alarms that may be older than ten years.  Many older models switched 120VAC directly through the interconnect wire (it’s ORANGE if 120VAC, YELLOW or RED if 9 VoltsDC).  If you don’t install a compatible low voltage module with your new smoke alarms, you could very well impose 120VAC onto an interconnection circuit that’s only supposed to operate at a nominal low voltage DC.  This is extremely hazardous, will damage your new smoke alarms and may may actually cause a fire in your home!

 

 

What testing is required for a backflow preventer on a fire sprinkler system?

For the answer to this question, we’ll have to refer to NFPA 25 (2008) as well as the clarification provided in the 2013 Edition of the same Standard.  Clause 13.6.2.1 of NFPA 25 (2008) reads:

    “All backflow preventers installed in fire protection system piping shall be tested annually in accordance with the following:

      (1) A forward flow test shall be conducted at the designed flow rate, including hose stream demand, of the system, where hydrants or inside hose stations are located downstream of the backflow preventer.

      (2) A backflow performance test, as required by the authority having jurisdiction, shall be conducted at the completion of the forward flow test.”

NFPA 25 (2013) Clause 13.6.2.1 reads:

    “All backflow preventers installed in fire protection system piping shall be exercised annually by conducting a forward flow test at a minimum flow rate of the system demand.”

Clause 13.6.2.2 of the same Edition reads:

    “Where hydrants or inside hose stations are located downstream of the backflow preventer, the forward flow test shall include hose stream demand.”

The answer is:

There are two tests required on a backflow preventer serving fire protection system piping.  The forward flow test and the performance test and since this is required on an annual basis, the permanent installation of a suitable test header must be undertaken.

How often must a sprinkler system be inspected?

NFPA 25 (2008) requires a number of inspections be performed on your sprinkler system.  Your fire safety plan manual should outline what they are.  There are daily, weekly, monthly, quarterly, semi-annual, and annual testing/inspection requirements, most of which have to be physically documented on forms similar to what you’ll find in the Sprinkler Test section of the Annual Building Life Safety Systems Test Report. You’ll need to access the sprinkler room and should have received some training on what to look for (normal valve open / closed positions, gauge readings, fire pump controller switch positions and visual indicators, etc.).  The air pressure gauge on your dry sprinkler system should be marked with indications for compressor on and off pressures as well as a mark for the low air switch activation.  If these aren’t indicated, then you should request your service provider to do so.  Fire sprinkler systems must undergo an annual inspection, with some systems requiring additional inspection and testing on a two, three or five year cycle.

Why is the air compressor on my sprinkler system activating every sixty seconds or so?  Is this normal?

There are two reasons this might occur.  You could have a pinhole leak (caused by corrosion) or an improperly installed coupling.  The compressor pressure switch may be installed incorrectly ahead of the check valve.  If this is the case, then the switch is activating when the line from the compressor is purged following an operating cycle (this process is often indicated by an audible hiss when the unit shuts down).  In this instance, moving the pressure switch to the other side of the check valve will solve this problem.

How often should the air compressor on a dry sprinkler system be serviced?

Good question!  Many dry sprinkler systems employ compressors that utilize a sight glass which enables you to visually check both the level and colour of the oil.  When the oil is milky in appearance, this is an indication that water is present.  When the oil is dark brown or black, it should be changed.

How often should our kitchen fire suppression system be serviced?

Every six (6) months.  Fusible linkages should be replaced on a regular basis (in accordance with the manufacturer’s service requirements), and the nozzles checked.

 

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