Water Restoration Structural Drying And Fire Sprinkler Response Temperatures

Sprinkler Head Types

There are a number of different types of sprinkler heads that meet different needs. This article covers the operation types (fusible link vs. bulb), the distribution types (pendant, upright, sidewall), and response temperatures.

Fusible Link Sprinklers vs. Glass Bulb Sprinklers

All wet-pipe sprinklers are held closed by either a fusible link or a glass bulb that contains a heat-sensitive liquid.

A fusible link sprinkler head has a two-part metal element that is fused by a heat-sensitive alloy. The link holds the pip cap, or plug, in place. Once the ambient temperature around the sprinkler head reaches a specified temperature, the alloy releases and the metal elements separate, which causes the pip cap to fall away. Water is then released. Note that water is only released by sprinkler heads where the ambient temperature reaches a specified level - therefore, water is only released in the area of a fire, which helps limit water damage.

Glass bulb sprinkler heads have a small glass reservoir that holds a heat-sensitive liquid. This glass bulb holds the pip cap in place. When the ambient temperature of the liquid reaches a certain level, the liquid expands causing the glass bulb to break, which allows the pip cap to fall away releasing water. As with the fusible link heads, water is only released where the ambient temperature reaches a certain level, which helps limit water damage.

Sprinkler Response Temperatures

Since ambient air temperatures can vary widely depending on the use of a space or surrounding environment, sprinklers come rated for different activation temperatures. The table below is based on NFPA 13 table 3-2.5.1 (US National Fire Code); however, manufacturers may have sprinklers with different temperature ratings.

CLASSIFICATIONMAXIMUM CEILING TEMPERATURESPRINKLER ACTIVATION TEMPERATUREGLASS BULB COLORFUSIBLE LINK COLOROrdinary100°F135°F - 170°FOrange (135°F)

Red (155°F)black; no colorIntermediate150°F175°F - 225°FYellow (175°F)

Green (200°F)White High225°F250°F-300°FBlue Blue Extra High300°F325°F - 375°F Purple RedVery Extra High375°F400°F - 475°F Black Green Ultra High 475°F500°F - 575°F BlackOrange Ultra High 625°F 650°F Black Orange

Standard Response (SR) Fire Sprinkler Heads

Standard response sprinkler heads work by wetting and cooling areas surrounding a fire to prevent it from spreading. Once the fire consumes all of the fuel around it, it goes out. Standard response fire sprinklers are individually activated, meaning only sprinkler heads directly above the fire will activate.

Quick Response (QR) Fire Sprinkler Heads

Primarily used for light hazard applications, quick response fire sprinkler headsdischarge water higher up on the ceiling. This cools the ceiling, preventing flash-over and increasing people’s odds of survival as they attempt to evacuate. QR fire sprinkler heads are standard for highly populated buildings such as health care facilities, assisted living facilities, and residential occupancies.

Differences Between Standard and Quick Response Sprinkler Heads

The biggest difference between quick response and standard response sprinkler heads is their activation temperatures. As the names suggest, quick response sprinkler heads activate slightly more quickly.

Physically, the only difference between a standard response fire sprinkler and a quick response fire sprinkler is the size of the bulb—standard response sprinklers have a 5 mm glass bulb, while quick response fire sprinklers have a 3 mm glass bulb.

While quick response fire sprinkler heads may seem like the obvious choice, there are other important factors to consider, including:

• Ceiling height
• Ambient temperature throughout the year
• The size of the area to be protected

All of which will determine whether it’s more effective to install a standard response of quick response sprinkler heads.

Maximum Ceiling TemperatureTemperature RatingTemperature ClassificationColor Code (with Fusible Link)Liquid Alcohol in Glass Bulb Color100 °F / 38 °C135-170 °F / 57-77 °COrdinaryUncolored or BlackOrange (135 °F / 57 °C) or Red (155 °F / 68 °C)150 °F / 66 °C175-225 °F / 79-107 °CIntermediateWhiteYellow (175 °F / 79 °C) or Green (200 °F / 93 °C)225 °F / 107 °C250-300 °F / 121-149 °CHighBlueBlue300 °F / 149 °C325-375 °F / 163-191 °CExtra HighRedPurple375 °F / 191 °C400-475 °F / 204-246 °CVery Extra HighGreenBlack475 °F / 246 °C500-575 °F / 260-302 °CUltra HighOrangeBlack625 °F / 329 °C650 °F / 343 °CUltra HighOrangeBlack

What is the temperature that fire sprinklers go off?

You don't need to worry about your building's heating system setting off the fire sprinklers (unless it catches fire!). The lowest temperature required to activate most fire sprinklers ranges from 150 – 165 degrees – levels of heat only a fire would produce