Three fire sprinklers

A few simple tips can streamline fire sprinkler replacement

Finding the right fire sprinkler replacement can be challenging. Do you have a 1/2" or 3/4" fire sprinkler? Is it standard response or quick response?

If you don't know the answers to those two questions, you're not alone. Knowing the answers to a few simple questions can make all the difference when ordering replacement fire sprinklers. In this article, QRFS provides five tips to help you properly identify and replace a malfunctioning, mismatched, or otherwise unsuitable head.

Tip 1: Get expert help when replacing sprinklers

A qualified professional should replace fire sprinklers or in any other way modify a fire sprinkler system. If you do not know a trusted sprinkler contractor, contact us at [email protected] or phone at (888) 361-6662. You can also read our entry on selecting a fire sprinkler contractor. We'll point you in the right direction.

Tip 2: Measure from the inside, not the outside

A fire sprinkler's size describes the inner orifice diameter—either half inch (1/2"), three-quarter inch (3/4"), or in some very rare cases one inch (1"). If you measure the outside diameter of a half inch (1/2") sprinkler's threads it will read close to three-quarters of an inch. The outside diameter of a three-quarter inch (3/4") sprinkler is almost one inch.

In our experience, most customers need a 1/2" fire sprinkler. When ordering replacements, if the outside diameter of the sprinkler's thread is (3/4") three-quarters of an inch you should request a (1/2") half-inch sprinkler.

Fire sprinkler orifice view

This is a half-inch fire sprinkler head. If you measure the orifice, or hole, at its widest diameter, you'll find that it's roughly 1/2" across. If you measure the wrong way—from thread to thread across the outside diameter—you'll end up with a measurement of 3/4".

Tip 3: Check the deflector for the response type

Always to match the sprinkler's response type to the one you're replacing. Replace quick response fire sprinklers with quick response fire sprinklers. Replace standard response fire sprinklers with standard response fire sprinklers—unless fire code or fire officials recommend using quick response sprinklers instead. The difference is critical: quick-response sprinklers activate more quickly and specialize in helping a building's occupants safely escape. Standard-response sprinklers activate later and attempt to keep a fire in its place of origin.

For more on the difference between quick- and standard-response fire sprinkler heads, click here.

There are two ways to tell a sprinkler's response type. You can typically find the letters SR (for standard response) or QR (for quick response) stamped on the deflector—the round piece of metal located at the tip of the sprinkler head.

Fire sprinkler deflector with stamp

The "QR" stamped on the right-hand side of this head's deflector indicates that it's a quick-response fire sprinkler.

An alternative is to look at the width or diameter of the bulb. A 5 mm bulb is standard response, while the significantly slimmer 3 mm bulb indicates that it's a quick response sprinkler. However, not all sprinklers have a bulb. Instead, some have temperature-sensitive metal components that allow the sprinkler to spray when surrounding temperatures rise.

Standard response vs quick response sprinkler

Bulb size is a subtle but important difference with life-saving implications. The larger 5 mm bulb on the left activates more slowly than the 3 mm bulb on the right.

Tip 4: Keep spare sprinkler heads as required by code

Spare fire sprinkler heads and a wrench should be stored in an impact-resistant sprinkler head cabinet (available here). This cabinet must remain accessible at all times in a facility with a fire sprinkler system installed. State regulations often apply in this matter. Check with your local fire department.

Spare sprinkler head cabinet

Spare fire sprinklers placed in a cabinet are more than a good idea—in most cases, having extras on hand is a code requirement.

Cabinets generally require matching sprinkler wrenches and a list of the property's existing sprinklers. For more on these requirements, check out our article on fire sprinkler head cabinets.

Tip 5: Conduct professional and do-it-yourself inspections as required

If you take nothing else from this article, remember: fire sprinkler systems should be visually inspected often—generally, on a monthly basis—and professionally inspected annually. Failure to conduct these inspections can result in code violations and place anyone in any building at risk. It's always better to be safe than sorry.

The following resources can help you learn more about what fire sprinkler system inspections entail:

If you're ordering replacement fire sprinklers for your residential or commercial building, take a look at what QRFS has to offer. We carry commercial fire sprinklers and residential fire sprinklers in a wide variety of sizes, response types, and finishes to suit your building's needs.

Cherry wood cover plate

Our stock of fire sprinklers even includes fully-functional concealed heads designed for when aesthetics are a priority.

View our selection of commercial fire sprinklers, or our selection of residential fire sprinkler heads.

Still confused? Need help choosing a replacement head? You can search our knowledge base using the search bar above, call us at (888) 361-6662, or email [email protected].

This blog was originally posted at If these fire sprinkler tips proved helpful, check us out at or on Twitter @QuickResponseFS.