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How to Use Flexible Drops with BlazeMaster® Fire Protection Systems

By: Paul Winstead on April 24th, 2024

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How to Use Flexible Drops with BlazeMaster® Fire Protection Systems


When installing a fire sprinkler system, it’s common practice to use hard pipe for armovers and drops to connect branch lines to the sprinkler head – a time-consuming process that is prone to errors causing costly rework and delays.

Flexible drops are a popular alternative first introduced in Japan in 1980 to avoid compromising fire protection systems in seismic events. In the 1990s, flexible sprinkler hoses started to be used in cleanrooms and duct systems in the United States, and their use grew from there into applications like schools and hospitals.

What many designers and contractors don’t know is that flexible sprinkler drops can be used with BlazeMaster® Fire Protection Systems. Using flexible drops with BlazeMaster pipe and fittings offers:

  • Easier, faster installation. It takes about one-third the time to install a flexible drop with BlazeMaster CPVC compared to a hard-pipe connection to the sprinkler head. An installer can possibly install 50 flexible drops in a day compared to average 15 for hard pipe. The time savings can help contractors address today’s labor shortage.
  • More flexibility for future renovations. If walls move and sprinkler heads need to shift, flexible drops are easy to adjust. If changes to the piping layout are needed, BlazeMaster CPVC can be easily fabricated and joined on-site, eliminating the need for messy cutting oils.
  • Versatile applications. Using BlazeMaster pipe and fittings for flexible drops is ideal for any project with a finished ceiling (drywall or acoustic ceiling tiles) – schools, hospitals, offices, and many other commercial and residential projects. BlazeMaster Fire Protection Systems are UL listed and FM approved for use in all NFPA 13 light hazard commercial and residential applications, including new construction and retrofits.

Designing and Installing Flexible Drops with BlazeMaster® Fire Sprinkler Systems

Designing a BlazeMaster fire sprinkler system with flexible drops is a straightforward process using ready-made screw-on adapters or mechanical couplings to attach the drop to the branch line and sprinkler head. There are a variety of couplings that meet the requirements of ASTM, UL, and FM. Our BlazeMaster CPVC manufacturing partners, Tyco and Viking, offer couplings that make the attachments easy and affordable.

To install a flexible drop, connect the line to the outlet in the branch line. The sprinkler head is connected to the other end of the flexible drop. Once the ceiling grid is installed, an installer can go to the job site and locate the drops in their final location. The fitter installs a bracket to support the flexible drop, puts the flexible drop into the bracket, and cuts the ceiling tile. This takes about 10 minutes or less on average per sprinkler head.

That’s much simpler than installing hard pipe armovers. Installers must wait until the acoustic ceiling tile is put in to know the lengths of the armover and drop. Unless the design and pre-fabrication of armovers was 100% accurate, the work must be done on-site. It’s a challenging process – trying to plan the installation from drawings is almost impossible. It’s typically a two-person job, with one installer on a ladder making measurements and calling down to a partner with a power machine who cuts the pipe for the armover. This process could take an estimated 15 - 30 minutes for each sprinkler head, depending on the complexity of the ceiling installation.

This time could be extended dramatically for more complex situations where the installer needs to install drops around duct work, cable boxes, plumbing lines, and other mechanical and structural members located within the interstitial space. It may also take more time if the armover is greater in length and may require an additional hanger as required by NFPA 13.

Flexible drops eliminate all that complexity. They are available in a wide range of lengths, up to six feet, so installers can work around anything that’s above the ceiling.

Flexible drops also streamline system testing as per Section of NFPA 13 (2022): “Unless permitted by through, all piping and attached appurtenances subjected to system working pressure shall be hydrostatically tested at 200 psi (14 bar) and shall maintain that pressure without loss for 2 hours.” With hard-pipe sprinkler drops, the installer may need to hydrostatically test of the system again after the sprinkler heads have been installed. With the use of flexible drops, the installer can complete the hydrostatic test as per NFPA 13 during the rough-in stage.

Flexible drops are a smart option for installing BlazeMaster fire sprinkler systems, especially when it comes to saving time and avoiding corrosion. For more information, contact our expert technical support team.

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