Sprinkler heads are an important piece of your intricate sprinkler system. As such, it is necessary to understand how they work and what is required in maintaining them.
A fire sprinkler system is made up of a network of piping connected to a water supply. Individual sprinkler heads are placed along the piping to protect the area beneath them. These sprinklers individually activated by a heat source. Unlike in the movies, when a fire occurs only the sprinkler head above the fire activates, efficiently applying water only where it is needed.
How a Sprinkler Head works
Each sprinkler head consists of a plug held in place with a trigger mechanism. The most common type of trigger is a glass bulb filled with heat-sensitive, glycerin-based liquid. When the temperature around the sprinkler head is high enough to expand the glycerin-based liquid (most commonly designed at 155 degrees) the glass bulb breaks and the plug is forced out by the pressurized water or air in the pipes. This allows the water to flow out of the sprinkler and directly into the deflector plate of the sprinkler head which is designed to distribute water in an even pattern. Water will continue to flow until the main valve is shut off.
A less common trigger mechanism than the glass bulb is a two-part metal link which is held together with a solder point. When the ambient temperature is high enough to melt the solder point, the plug is released and water flows over the sprinkler head.
Smoke will not activate a fire sprinkler and only the sprinklers close enough to the heat source to reach the rated temperature activate. When a sprinkler activates, the water flows forcefully down over the flames, extinguishing them completely in most cases, or at least controlling the heat and spread of the fire and limiting the development of toxic smoke.
Sprinklers are so effective because of how quickly they react. They reduce the risk of death or injury from a fire because they dramatically reduce heat, flames and smoke which gives people time to evacuate.
Required and Recommended Inspections and Testing
As you can see, sprinkler heads are an important component of your sprinkler system. They must be inspected visually annually. Sprinkler head inspections ensure that water can discharge properly; they are checked for obstructions, damage, corrosion, and paint or other foreign material which may interfere with the sprinkler head operation.
Once your sprinkler heads are 50 years old, they should be tested at that time, followed by testing every 10 years after until they are 75 years old, at which point they must be tested every 5 years. Unlike plumbing, electrical, or HVAC systems, sprinkler systems can sit inactive for years if no fire emergency occurs. As a result of this idleness, proper testing is the only way to ensure the sprinkler system and the sprinkler heads are working correctly. To test your sprinkler heads, your Life Safety Partner will remove 1%, but at least 4, of your sprinkler heads from different areas of your sprinkler system and perform a plunge test. The plunge test measures the amount of time it takes for the sprinkler head to activate. If a sprinkler head fails, then all sprinkler heads in the area from where that particular head was taken must be replaced.
Dry-type sprinkler heads have a much higher failure rate than other types and must be tested every 10 years, starting at 10 years instead of 50. This is due to their susceptibility to corrosion both internally, when moisture condenses inside the device, and externally. In addition, dry-type sprinklers are usually installed in harsher environments which provide greater opportunity for damage to the sprinkler heads. In addition sprinklers with fast response elements should be tested every tested or replaced after 20 years and sprinklers exposed to a harsh environment every 5 years. You should consult with your Life Safety Partner about the costs of testing them versus replacing them.
Another requirement for sprinkler heads is that you have a cabinet with spare heads onsite. A sprinkler head may need to be replaced for any number of reasons, it may have become coated with a foreign material or activated due to a fire. The area the sprinkler was protecting is now unprotected until it is replaced. Worse, if the sprinkler is damaged and cannot hold pressure, the entire sprinkler system must be shut down and is rendered inoperable which leaves the entire facility unprotected. Sprinkler heads need to be replaced as quickly as possible to keep your system running or get it back in service. There are many different sprinkler head types, depending on the availability of the type you need it could take days or even weeks to order a new one. Keeping extra sprinkler heads onsite is required and ensures uninterrupted fire protection of your business, life, and property. You can read more about spare sprinkler head cabinet requirements here.
Posted on: October 20, 2016