Quick answers
What are the 4 types of fire sprinkler heads?
Pendent, concealed, upright and sidewall. Pendent, upright and sidewall describe the discharge orientation, while a concealed sprinkler is a pendent type hidden behind a listed cover plate that releases when heated.
Do all sprinkler heads go off at once in a fire?
No. In an automatic sprinkler system, normally only the sprinkler or sprinklers heated enough by the fire operate. Each responds to heat at its own thermal element, not to smoke alone.
Can sprinkler heads or cover plates be painted?
No. Painting, caulking or swapping a cover plate can delay or prevent operation. Report painted, corroded, leaking or damaged sprinklers for replacement by a qualified fire-protection professional.
What does the colour of a sprinkler bulb mean?
It shows the temperature at which the bulb bursts. Orange opens at 57°C, red at 68°C, yellow at 79°C, green at 93°C and blue at 141°C. Higher ratings are used near ovens, boilers and hot roofs so the head does not open from normal working heat.
What is the difference between quick response and standard response sprinklers?
A quick response head usually has a thin 3 mm bulb and opens earlier in a fire, which helps protect people in the room. A standard response head usually has a 5 mm bulb and is common where the aim is to protect the building and stock.
What is the K-factor of a sprinkler head?
It tells you how much water the head lets out at a given pressure. A higher K-factor means more water. The common half-inch head is K 5.6 in US units, while storage sprinklers for high-rack warehouses go up to about K 33.6.
Sprinkler systems are one of the best ways to keep your buildings safe from fire. Not all fire sprinkler systems are made equal. There are many different kinds of fire sprinkler systems and sprinkler heads that can be used with them. Depending on the area you want to protect, the type of sprinkler head you use may be different. Some of the most common types of sprinkler heads are:
- Pendents:- This type of fire sprinkler head is the most common. A sprinkler head in the shape of a pendant hangs from pipes near the ceiling. Pendent sprinklers remain visible after installation. This type of sprinkler head has a convex, circular, gapped deflector plate that spreads water out in a conical pattern.
- Concealed Pendents:– Places that need fire sprinklers but want them to look nice do not show the heads. This kind of sprinkler head is built into the ceiling and has a decorative cap on top. The cover plate is held on by a low-melting solder. When a fire heats it, the solder melts and the plate falls away first; more heat then makes the sprinkler itself operate. Never paint a cover plate or swap it for one from another model.
- Upright:- The sprinkler heads are straight up and point to the ceiling. This type of sprinkler head has deflectors that are bent down to spray water in a hemispherical pattern. Straight sprinkler heads work well in places where there are obstacles, open ceilings, or places that are hard to reach, like beams and ducts.
- Sidewall:– Sprinkler heads on the side of a wall are called sidewall sprinkler heads. These are separate listed models made to be fitted on or near a wall. They have their own deflector design and throw water out from the wall into the room in the pattern their listing allows. Sidewall sprinkler heads are put in small rooms, hallways, and other places where the fire sprinkler pipes go up the walls.
Which Fire Sprinkler Head is Right for You?
Talk to a fire protection expert if you want to figure out which type of fire sprinkler head would work best for your situation. They can help you figure out which sprinkler head will protect your application the best.
Bulb colours, temperature ratings and response speed
Look closely at a glass-bulb sprinkler and you will see a small bulb filled with coloured liquid. The colour tells you the temperature at which the bulb will burst and let the water out. The chart below is for standard-response heads with a 5 mm bulb, from one manufacturer’s identification chart; check the data sheet of the exact model fitted.
| Bulb colour | Opens at | Temperature class | Highest normal ceiling temperature |
|---|---|---|---|
| Orange | 57°C | Ordinary | 38°C |
| Red | 68°C | Ordinary | 38°C |
| Yellow | 79°C | Intermediate | 65°C |
| Green | 93°C (100°C on some models) | Intermediate | 65°C |
| Blue | 141°C | High | 107°C |
| Mauve | 182°C | Extra high | 149°C |
| Black | 260°C | Ultra high | 240°C |
The last column matters as much as the colour. Where the ceiling stays below 38°C, as in most ordinary rooms, orange or red heads can be used. Over a bakery oven, a boiler or under a hot tin roof, the designer picks a higher rating so the head does not burst from normal working heat. If you change how a room is used, for example turning a store into a kitchen, ask your fire consultant whether the heads still suit it.
Quick response and standard response
A quick-response head usually has a thin 3 mm bulb; a standard-response head usually has a 5 mm bulb. The thinner bulb heats up faster, so it opens earlier in the fire. Engineers measure this with the Response Time Index (RTI): 50 or less for quick response, 80 or more for standard response. Quick response is used where people’s lives are the main concern, because early water keeps the room cooler for longer. Standard response is common where the aim is to protect the building and stock until the fire brigade arrives.
K-factor in one line
The K-factor tells you how much water a head lets out at a given pressure: a bigger K means more water, and the common half-inch head is K 5.6 in US units.
Which head suits which building
- Homes and flats: residential fast-response sprinklers, made to stop a room reaching flashover so the family has time to get out. Concealed or sidewall versions are chosen where looks or ceiling space matter.
- Offices, shops and hotels: quick-response pendent or concealed heads below the false ceiling, and upright heads above it or where the pipes run exposed.
- Warehouses and godowns with high racks: large-orifice storage sprinklers, such as ESFR (Early Suppression Fast Response) heads from K 22.4 to K 33.6, which throw heavy drops that can push through a strong fire plume. Rack height, what is stored and roof height decide the design, so this is never a plain swap from office heads.
In India, sprinkler design and installation follow IS 15105:2021, and the National Building Code of India 2016, Part 4 (Fire and Life Safety), sets fire protection requirements by type of occupancy and building height. Your fire NOC conditions and the local fire service have the final word. When a head is replaced, the new one must match the old in colour, K-factor, response type and orientation unless a designer has approved the change.
What needs attention
- Pendent sprinklers direct water downward onto a deflector below the orifice
- Upright sprinklers use a deflector above the orifice and are common where piping is exposed
- Sidewall sprinklers produce a listed directional pattern from a wall and are not simply half of a pendent sprinkler
- A concealed cover plate releases when heated before the sprinkler operates; it does not fall because room temperature drops
- Only the sprinkler or sprinklers heated sufficiently by a fire normally operate; all heads do not automatically open together
- An attractive concealed finish does not permit painting, caulking or substituting a cover plate
- Obstructions and ceiling features can delay activation or block water even when the chosen orientation looks correct
Controls that reduce risk
- Read the model and temperature marking from a safe position without touching the sprinkler
- Compare every installed model with the approved sprinkler schedule and hydraulic drawings
- Check ceiling pockets, beams, ducts, racks and new services for obstruction conflicts
- Remove storage encroachment according to the approved clearance requirement
- Flag painted, corroded, leaking, loaded, bent or mechanically damaged sprinklers for qualified replacement
- Keep the correct listed spare sprinklers and wrench in the required cabinet
- Require fire-protection review before any ceiling, partition, light, HVAC or storage change
- Document model, orientation and location during inspection rather than recording only 'heads checked'
Common unsafe practices
- Calling concealed pendent a completely separate orientation instead of a listed pendent variant
- Selecting a sprinkler by appearance, price or pipe direction alone
- Painting a sprinkler or cover plate during renovation
- Using a cover plate from another model, manufacturer or temperature rating
- Installing a pendent sprinkler upright or an upright sprinkler pendent unless the exact listing permits it
- Adding ducts, lights, signs, shelves or tall storage beneath sprinklers without design review
- Hanging decorations, cables or objects from sprinkler frames or pipe
- Replacing a damaged head without matching model, K-factor, response, temperature and listing
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