What is a Fire Sprinkler?
A fire sprinkler is one component of a fire sprinkler system. The sprinkler itself is commonly called a ‘sprinkler head’ or just the ‘sprinkler’. The sprinkler head is tied to a network of pipes that delivers a fire retardant onto a fire. Water is the most common type fire retardant used in commercial and residential systems. There are two primary types of sprinkler heads, Automatic fire sprinklers and Open head sprinklers.

How Does A Fire Sprinkler Work?
An Automatic fire sprinkler is held in a closed state by a glass bulb or a two-part metal link. These ‘links’ or ‘bulbs’ use pressure to hold a cap in place which acts as a plug in the system. These links are designed to break at a specified temperature. When heat from a fire rises to a set temperature, the metal link will melt or the glass bulb will break. This releases the cap and allows water to flow through the opening onto the deflector which sprays the water over the coverage area.

The glass bulb is usually filled with a fluid consisting of a non-toxic proprietary glycerin solution. The size of the air bubble within the glass tube determines the heat level needed to break the glass bulb and release the plug.

The color of the bulb helps identify the level of temperature needed to break the bulb and activate the sprinkler head.

• 135-170 Degrees = Red
• 175-225 Degrees = Green
• 250-300 Degrees = Blue
• 325-375 Degrees = Purple
• 400-650 Degrees = Black

The picture of the flowing head (shown in the section below) shows a conventional style head, which are pretty much obsolete. That kind of sprinkler was based on the idea that it was advantageous to put some of the water upward to cool the ceiling.FM testing later showed that cooling the ceiling was much less effective than applying all of the water downward to the fire. All modern sprinklers spray water in a downward parabolic pattern. You can literally sit on the sprinkler piping without getting wet by the sprinkler.

Conventional sprinklers are used in special situations and are required for some installations. When sprinklers cover a pier, they are installed below the fire. In that case conventional heads are used to spray the fire from below. We have yet to see sprinklers on a pier however.

A metal link sprinkler like the one shown to the left, come in many proprietary shapes and designs. Each one operates in the same basic manner. Heat from a fire rises to the head and melts the metal link. Once the link has been compromised, the head releases the cap and opens the sprinkler for water to spay over the coverage area. Most metal link sprinklers also utilize some form of spring device to ensure all the cap components “spring” out of the head and away from the cap. This is a fail safe measure to ensure the head will not fail or be encumbered in some way by the link parts.

An Open Fire Sprinkler (or open nozzle) is a sprinkler head that does not have a heat-sensitive element. Water is not present in the piping system until needed. These heads rely on a fire alarm system to release water at a control valve installed on some other location of the system.

Fire Sprinkler Categories:
There are several categories of sprinklers that most manufactures adhere to. The categories help organize the types of coverage areas that require a sprinkler. But each category may cover varying types of hazards for that space.

• Standard Spray Sprinklers
  Standard spray sprinklers are used in light, ordinary, or extra hazard commercial occupancies.
• Extended Coverage Sprinklers
  Extended spray sprinklers are used in light or ordinary hazard commercial occupancies. The main difference between standard and extended spray is that the extended coverage sprinkler lets you use fewer heads for the same area; provided they calculate on the system.
• Storage Sprinklers
  As their name implies, these are special designed sprinklers for most any kind of storage occupancies. This can include mechanical parts, lumber, canned foods etc.
• Residential Sprinklers
  These sprinklers are used only for residential occupancy. They are designed with ascetics in mind, but are just as functional as other sprinkler heads.
• Dry Sprinklers
  Dry sprinklers are designed to be installed in areas of buildings where the sprinklers or water supply pipes may be subject to freezing, such as unheated attics, freezers and coolers, parking garages, porches and warehouses. Dry heads are primarily used on dry systems where you want a pendant head installed.
• Special Sprinklers
  Once again as their name implies, these are special sprinkler heads designed to protect special areas. For example, special heads with coatings for corrosive areas. Attic heads are designed to protect attic areas with sloped roofs.

Fire Sprinkler Types:
There are four different types of sprinkler heads. These define the location and type of spray the head will deliver to a fire.

• Pendants – This is the most common sprinkler used in commercial buildings. They extends down from the ceiling and spray streams downward over the deflector.
• Uprights – Sit on top of the piping and spray up towards the deflector which disperses water downward over the coverage area.
• Sidewalls – These heads come out of the wall to protect hall ways or small rooms.
• Special Coverage – This type of sprinkler head is designed to protect special areas. For example, special heads with coatings for corrosive areas or to match decorative areas. Attic heads are designed to protect attic areas with sloped roofs.

HFP has designed several commercial, industrial and residential sprinkler systems for our clients. We have the knowledge and experience to help you lay out a plan and design a system that’s right for your business or home. You can learn more about HFP, our experience and services by visiting our Home page or calling us at 704.877.2553

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