Flexible sprinkler drops can offer a range of significant benefits, depending on the installation scenario
The finishing touches in any project can be the hardest part, and fire sprinkler systems are no different. Measuring and cutting pipe for sprinkler drops—and installing the sprinklers themselves—is one of the last things that happens during a system installation and requires time-taking attention to detail. But fire sprinkler whips, also called flexible sprinkler drops or drop hoses, can speed this process up because they’re bendable.
These braided wire hoses are UL Listed and FM Approved to replace the last few feet of pipe leading to fire sprinklers, among other applications. Their bendability simplifies and quickens sprinkler installation and provides a few more benefits when replacing straight, rigid pipes. But there are some considerations before using them.
Read on to learn these pros and cons:
- Pro #1: Ease of installation and adjustment
- Pro #2: Preventing the effects of ceiling creep
- Pro #3: Seismic protection
- Con #1: Cost compared to straight pipe
- Con #2: Hydraulic pressure loss
If fire sprinkler whips are right for your project, QRFS has the parts you need. Shop our selection of flexible drops and mounting brackets today!
Pro #1: Fire sprinkler whips are simple to install and adjust
Basically, it’s pretty easy to install fire sprinkler whips. Flexible drops reduce the amount of precise measurement, pipe cutting, and pipe threading or grooving (and with that, cutting oil) needed for sprinkler installation. All pros do is:
- Join the whip to the branch line. Many use a threaded connection, but grooved joints are also available.
- Mount the support bracket on the ceiling frame.
- On the bracket, position the clamp horizontally.
- Clamp the sprinkler whip in place, using the ruler guide to get the correct position vertically.
This video from ASC Engineered Solutions shows how to do it:
Compared to traditional rigid piping, sprinkler whips can save a lot of manhours on the job site, especially where a pipe arrangement called a return bend instead of a simple drop is needed. Rather than connecting the sprinkler directly to the branch line with a length of rigid pipe, a return bend goes up, to the side, and down, as shown below:
A purpose of this layout, which NFPA 13: Standard for the Installation of Sprinkler Systems (2025 edition) requires in specific circumstances, is to prevent sediment buildup in sprinkler drops. For example, when the water supply is a raw water source,such as a pond, a return bend may be required (NFPA 13: 16.3.12.1-2). Return bends are also needed when using pendent or sidewall non-dry-barrel sprinklers in climate-controlled sections of a dry system (8.2.2.1.1). Again, this pipe configuration prevents loose sediment and debris from accumulating just above the sprinkler.
Return bends can be fairly labor-intensive. Measuring, cutting, and grooving or threading these short lengths of pipe takes time and parts that could be saved by using a fire sprinkler whip.
Sprinkler whips allow for easy adjustment
Sometimes, a system installer or maintainer needs to adjust the position of a sprinkler. The ceiling or other parts of the building may settle and shift, putting the sprinkler out of position. Perhaps a new obstruction or change to building utilities may require a slight repositioning of a sprinkler head. Whatever the reason, adjusting flexible sprinkler drops is much easier than replacing rigid pipes.
To adjust a sprinkler’s position with rigid drops, pros must isolate and drain the pipe and then redo the piping. This isn’t necessarily so with a flexible sprinkler drop that needs mild changes—pros can loosen and reposition the clamp and bracket, bend the sprinkler whip into place, and re-tighten.
However, just because sprinkler whips make adjustments easy doesn’t mean anyone can or should do it. The exact positions of fire sprinklers are an integral part of sprinkler system design. (You can read more about the rules for sprinkler spacing and the avoidance of obstructions in our previous blog posts.) Because sprinkler position is so important, NFPA 13 requires a warning label on flexible drop anchors to prevent adjustment or movement of sprinklers by unqualified personnel (17.4.1.3.3.4).
Pro #2: Sprinkler whips help prevent the effects of ceiling creep
All buildings and structures move and settle a bit over time, but this is especially true for suspended ceilings with easily movable tiles.
Suspended ceilings, also called false ceilings, conceal plumbing, fire sprinkler pipes, HVAC ducting, electrical systems, and the building’s structural elements above (usually off-white) panels. The tiles keep utilities out of sight while providing easy access. However, the flexible nature of these ceilings allows them to move easily relative to rigid building elements. This is sometimes called “ceiling creep.”
As Means of Escape explains, this combination of a creeping flexible ceiling and inflexible sprinkler pipe can lead to the misalignment of fire sprinklers, resulting in temperature-activation problems or issues with spray pattern obstruction. Fire sprinkler whips can prevent this issue. Because the brackets for flexible drops mount directly to the false ceiling frame, sprinkler heads can move with the ceiling.
Pro #3: Reduced clearance needed for seismic protection
Piping systems are particularly vulnerable to earthquake damage. Unfortunately, earthquakes also increase fire danger by damaging gas and electrical infrastructure, making working fire sprinkler systems even more essential. The American Society of Civil Engineers (ASCE) defines specific categories of earthquake-prone areas where seismic design principles are needed. These are:
- Category C includes buildings essential for emergency response (hospitals, police, fire, defense) subject to moderate shaking, or buildings subject to more severe shaking.
- Category D includes buildings subject to severe and destructive shaking, but not near a major fault.
- Category E includes buildings near active, major faults.
- Category F includes buildings essential for emergency response near active, major faults.
In buildings that fall within these categories, flexibility is one seismic design principle that protects sprinkler systems against earthquake damage. And sprinkler whips can be useful tools to achieve it.
Our previous blog explained how flexibility and wide clearance around pipes and sprinklers reduce the risk of damage during earthquakes. If pipes and sprinklers have some freedom to move around without hitting the structure or being torqued against it, they’re more likely to survive an earthquake’s shake. That said, the flexibility of sprinkler whips may be used instead of clearance to achieve the same effect.
For example, both NFPA 13 and the International Building Code (IBC) say that fire sprinklers (really including drops) should be kept at least 3” away from the building’s “structural elements,” but this clearance gap isn’t necessary when sprinkler whips are used:
From the 2025 edition of NFPA 13
18.4.11 The installed clearance between a sprinkler and structural elements not used collectively or independently to support the sprinklers shall be at least 3 in. (75 mm).
A.18.4.11 Structural elements include, but are not limited to, beams, girders, and trusses. Frangible ceilings should not be considered structural elements for this purpose.
18.4.11.1 Where sprinklers are installed using flexible sprinkler hose, clearance for the sprinkler shall not be required.
These requirements are echoed in Chapter 16, “Special Inspections and Tests,” of the IBC (2024: 1705.13.6), except IBC specifies “automatic sprinkler system drops and sprigs” instead of NFPA 13’s general “sprinklers.”
Regardless, these components must usually be kept at least 3 inches from the building’s structural elements—beams, trusses, girders, and the like—so they don’t collide with these objects during an earthquake. However, sprinkler whips can be used instead of rigid drops because they flex and bend, eliminating the need for this amount of space.
This rule doesn’t address the clearance needed around sprinklers where they penetrate ceilings—in fact, NFPA 13 doesn’t seem to cover that at all. Instead, ASCE 7: Minimum Design Loads for Buildings and Other Structures (a publication of the American Society of Civil Engineers) is referenced by NFPA 13 and ICC codes and has the info.
Per ASCE 7, sprinklers in Category C buildings need 1/4″ clearance around their ceiling penetrations, and those in Categories D, E, and F need at least 1″ of movement in all directions. These clearance requirements might require using oversized “seismic” escutcheons or trim rings. However, alternatively, installers may avoid cutting large holes and using oversized escutcheons by using flexible sprinkler drops instead.
Con #1: Flexible sprinkler drops cost more per foot than rigid pipe
While sprinkler whips are easier and faster to install than custom-length rigid drops or armovers, flexible drops cost significantly more than an equivalent length of metal pipe. At wholesale prices, installers can get many feet of pipe for the cost of a relatively short flex drop.
To decide whether flexible sprinkler drops are worth it, pros have to weigh the cost of materials against the installation hours needed—and consider other sprinkler-whip advantages like ease of adjustment and seismic benefits. On a large project that requires putting in a lot of sprinklers, using flexible drops can make dollars and sense.
Con #2: Hydraulic considerations and equivalent feet of pipe
Water pressure is the guiding principle of fire sprinkler system design. Each choice, from the size of the pipes to sprinklers’ spacing and K-factors, is made to achieve enough water flow, pressure, and coverage (“design density”) to control or suppress a fire effectively. One way to help accomplish sufficient pressure and flow is to minimize pressure loss in the system due to friction as water moves to the sprinklers. Unfortunately, fire sprinkler whips cause significant pressure loss compared to straight pipes.
All fire sprinkler pipes and fittings cause pressure loss because of the friction their internal surfaces and shapes create against the flowing water. NFPA 13 details calculations like the Hazen-Williams formula to determine the pressure loss caused by friction in terms of PSI per foot of pipe. For fittings like elbows, NFPA 13 expresses pressure loss in terms of an equivalent length of pipe.
For example, using one 1” 90-degree elbow fitting for Schedule 40 steel pipe causes the same pressure loss as using 2 feet of straight pipe. You can read more about these calculations in our previous blog: “How Much Water Pressure is Required for Fire Sprinkler Systems?”
For all their benefits, fire sprinkler whips cause additional friction that fights against water flow. Just like a standard elbow fitting, the pressure loss caused by flex drops is calculated in terms of the equivalent length of pipe. Manufacturers publish this information in their data sheets. For example:
For example, a 28” SprinkFlex hose can have the same friction loss as 29 feetof 1” Schedule 40 Steel Pipe. During system design, these equivalents can eat into a water pressure ‘budget.’ The exact number depends on whether the system and Authority Having Jurisdiction require using FM Global values or UL values, as the two organizations have different standards and assume/allow different maximum quantities of 90-degree bends.
Note that Victaulic, which is famous for pioneering grooved pipe, offers some sprinkler drops (VS1 and VS2) that are sort of ‘no-calc’ (They require “No equivalent length calculations.”)
How? Victaulic does it by preinstalling specific sprinkler heads on the end of the whips that have larger orifices than their nominal K-factors. For example, a specific sprinkler/whip combo like the Victaulic VS1/V3505 has an effective, nominal K-factor of 5.6, but the hole leading into the sprinkler is larger than one in a normal 5.6k sprinkler. This extra room for water to move is precalculated to offset the additional friction created by the flexible drop.
For this reason, VS1 and VS2 users never just purchase a sprinkler whip; they also purchase a specific sprinkler with a unique sprinkler identification number (SIN). Regardless, regular whips that attach to a variety of sprinklers, including ones sold by Victaulic and other manufacturers, are more common. And they work well, as long as hydraulic calculations account for them and system pressure and flow are adequate.
Fire sprinkler whips: a useful and innovative tool in fire sprinkler systems
Fire sprinkler whips offer speed, convenience, and various functional benefits. At the end of a job, their quick installation saves labor for sprinkler fitters. And during the life of a sprinkler system, flexible sprinkler hoses mitigate the impacts of ceiling drift, allow easier repositioning, and offer seismic protection advantages. However, all these benefits must be balanced with some considerations when using them, including whips’ increased cost-per-foot and the hydraulic demand they may create.
If sprinkler whips right for your next project, QRFS has you covered. Our selection of SprinkFlex flexible sprinkler drops includes 1/2” and 3/4” hoses from 28” to 71” in length, plus mounting hardware. You can also contact our customer service team for help with a quote, to purchase other special models, such as no-calc whips, or additional accessories.
This blog was originally posted at blog.qrfs.com. If this article helped you, check us out on Twitter @QuickResponseFS.