Free hotel staff training · Safety & security

Fire Sprinklers

How sprinkler heads work, what sets them off by accident, the difference between wet and dry systems, and what to do in the first minutes of a discharge.

10 minutes to read. 9 questions to check yourself. Updated November 2026. Free, no account needed.

For: Front desk, Housekeeping, Maintenance, Managers

By the end you will be able to

• Explain how sprinkler heads activate
• Avoid the accidental triggers staff cause most often
• Take the right first steps when one discharges

This free hotel staff training covers how fire sprinklers actually work, what causes them to go off (including by accident), the difference between wet and dry systems, and what to do if one activates. Not every hotel has sprinklers, and not every activation is a fire, so knowing the basics protects both your guests and your property.

Newer or renovated hotels are usually required to have sprinkler systems under building and fire codes, while older hotels may have partial systems or none, depending on local regulations and whether upgrades were made. Whatever your property has, every employee should understand how sprinklers work and what to do when one discharges.

How a Fire Sprinkler Works

Most sprinkler heads hold a small glass bulb filled with a liquid that expands when heated. When the air around the head reaches the head's rated temperature, the liquid expands, the glass shatters, and water flows. Some heads use a metal fusible link instead of a bulb, but the idea is the same: heat releases the plug, and water follows.

A single head activates when:

• Heat from a fire reaches that head (a common rating in ordinary areas is about 155°F / 68°C)
• The liquid in the bulb expands
• The glass breaks and releases water

Forget what you have seen in movies. Sprinklers do not go off from smoke or steam alone, and they do not all activate at once. Only the head that gets hot enough discharges water, which is almost always the one closest to the fire.

Not Every Bulb Is Red

The bulb color tells you the temperature the head is rated for. Red (about 155°F / 68°C) is the most common in ordinary spaces like guest rooms, hallways, and lobbies. But hotter areas use different colors on purpose: kitchens, boiler rooms, laundry, and attics may have yellow, green, or other colors rated for higher temperatures so they do not trip from normal heat. A yellow-bulb head in the kitchen is not broken. It is the right head for that room.

Accidental Activation Is the Common One

In hotels, the majority of sprinkler discharges are accidents, not fires. A head can go off any time the bulb is struck or broken, such as:

• Hanging clothes, decorations, or anything else on a sprinkler head
• Striking it with equipment, luggage, a bed, or a ladder
• Horseplay or guest tampering

A single head can release roughly 15 to 40 gallons of water per minute. Left running, that adds up to serious water damage in just a few minutes.

Nothing is ever hung or attached to a sprinkler head. Not a coat, not a decoration, not a sign. If you see something hanging from a head, or an item stored close enough to hit one, report it to management right away.

Wet vs Dry Systems

The type of system depends on climate and building design, and many hotels use a mix of both.

Wet Pipe System (Most Common)

The pipes are always full of water, so when a head activates, water releases immediately. Simple and reliable, wet systems are used in heated indoor spaces, which is most of a hotel: guest room hallways, lobbies, and interior areas.

Dry Pipe System

The pipes are filled with pressurized air or nitrogen instead of water, held back by a valve at the riser. When a head activates, the air escapes, the valve opens, and water flows in, which means there is a short delay of a few seconds before water reaches the head. Dry systems are used in unheated or cold areas where standing water could freeze and burst the pipes, such as parking garages, exterior stairwells, and unheated storage. Many hotels run wet systems inside and dry systems in these colder areas.

If a Sprinkler Discharges: Emergency Response

This section is about an accidental discharge, not a fire. Shutting off a sprinkler is only done when there is clearly no fire, by trained personnel, because closing a valve turns off fire protection for that part of the building.

Life safety comes first, always. If there is any sign of fire, smoke, an active alarm, an electrical hazard, or water reaching electrical equipment, do not go shut off a valve. Evacuate and follow your property's fire emergency procedure. Never shut down a sprinkler during a fire or active alarm without the fire department's direction.

Step 1: Confirm there is no fire.

Be certain the discharge is accidental. If you are not sure, treat it as a fire and follow your emergency plan.

Step 2: Get a trained person to the riser room.

The fire sprinkler riser and control valves are usually in a dedicated riser room, and the valves are often locked open with a key. This is a job for maintenance, engineering, or whoever your property has designated and trained. Ask your supervisor to show you where the riser is and who is authorized to operate it, because every property is different.

Step 3: Shut off the affected zone.

Close the control valve for that zone, then open the drain valves. The drain step matters: even after the valve is closed, 100 gallons or more can stay trapped in the pipes and keep flowing to the open head by gravity, so opening the drains is what actually stops the water at the sprinkler.

Step 4: Notify and document.

• Maintenance or engineering, and the general manager
• The fire department or alarm monitoring company, if your policy requires it
• Insurance or corporate, if needed
• Photograph the scene and note the time, what happened, and what was done

Because a closed valve leaves that zone without fire protection, the system needs to be inspected and returned to service quickly. Your property may be required to post a fire watch until it is.

Never try to repair or reset a sprinkler head yourself. Only licensed fire protection professionals replace or reset components. If your property stocks a sprinkler stopper tool for stopping a single head fast, only trained staff should use it, and it does not replace getting a professional in.

Frequently asked questions

Do all sprinklers go off at once?

No. Each head activates individually by heat, so only the head above the fire discharges. The scene in movies where an entire floor sprays at once is not how these systems work.

What accidentally sets off a sprinkler head?

Physical impact is the main cause. Hanging clothes hangers, decorations, or signage from a head, or striking one with a ladder, cart, or furniture during a move.

What should staff do if a sprinkler discharges?

Pull the fire alarm and evacuate the area first, then call the fire department. Notify management and maintenance so the system can be shut down by someone trained to do it.

How much water comes out of one sprinkler head?

Enough to flood a room and the floors below very quickly. Water damage from a single accidental activation regularly runs into tens of thousands of dollars.

How much clearance is required below a sprinkler head?

Keep at least 18 inches of clear space beneath the head. Stacked supplies in storerooms are the most common violation found during inspections.