Fire Sprinkler Heads: Structure, Types, and Working Principle for Fire Safety

Nov 07, 2025

Fire sprinkler heads are a critical component of fire protection systems, designed to detect and suppress fires automatically. Let’s dive into their structure, types, and how they work to keep spaces safe.

What Are Fire Sprinkler Heads?

A fire sprinkler head is a water-spraying device that activates either automatically when exposed to heat within a preset temperature range or via control equipment in response to fire signals. It discharges water in a designed pattern and flow rate to extinguish or control fires.

Structure of Fire Sprinkler Heads

The design of a fire sprinkler head is relatively simple but highly effective, consisting of four main parts:

Sprinkler Head: The component that disperses water when activated.
Heat-Sensitive Glass Bulb: The core element, filled with liquids like kerosene or ether. These bulbs come in various colors and are engineered to burst at specific temperatures.
Pipe Plug: Seals the water pipe until the sprinkler is activated.
Water Pipe: Connects the sprinkler to the pressurized water supply network.

Types of Fire Sprinkler Heads

Fire sprinklers are categorized based on their installation orientation and coverage:

- Pendent Sprinklers: Installed downward from ceilings, ideal for open spaces.
- Upright Sprinklers: Installed upward, often used in areas with high ceilings or where debris might accumulate.
- Sidewall Sprinklers: Mounted on walls, designed to protect the area below and adjacent to the wall.
- General-Purpose Sprinklers: Versatile, suitable for both pendent and upright installations in standard environments.

The Role of Heat-Sensitive Glass Bulbs

The colored heat-sensitive glass bulb is the “brain” of the sprinkler. Here’s what each color signifies:

Red (68°C): The most common type, activating at 68°C – typical for residential and commercial spaces.

Yellow (79°C): Activates at 79°C, used in warmer environments like kitchens.

Green (93°C): Activates at 93°C, suitable for areas with higher ambient temperatures.

Blue (141°C): Activates at 141°C, used in industrial settings with extreme heat.

These bulbs are filled with liquids that expand rapidly when heated. When the surrounding temperature reaches the preset threshold, the liquid expands enough to shatter the glass bulb, triggering the sprinkler.

Working Principle of Fire Sprinkler Heads

Installation: Sprinklers are mounted on walls or ceilings, connected to a pressurized water pipeline.
Activation: During a fire, the heat-sensitive glass bulb is exposed to high temperatures. The liquid inside expands, causing the bulb to burst.
Water Discharge: Once the bulb breaks, the pipe plug is released, and water flows out through the sprinkler head in a designed pattern.
Fire Suppression: The water sprays continuously over the fire, either extinguishing it completely or controlling heat and smoke until the fire department arrives.

Fire sprinkler heads are a testament to engineering simplicity and effectiveness, providing 24/7 fire protection that can significantly reduce property damage and save lives. Whether in homes, offices, or industrial facilities, their reliable operation makes them an indispensable part of modern fire safety systems.

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