Heat trace systems for wet-pipe fire sprinkler systemsMay 14, 2019
Chromalox’s fire sprinkler pipe freeze protection system addresses operability, code approval, cost and installation approved to current NFPA 13, IEEE 515.1 and UL 515A standards for testing, design, installation and maintenance of electrical resistance heat tracing systems for wet-pipe fire sprinkler and standpipe systems.
Several other manufacturers previously listed and approved to UL 515 standards have since been delisted, as the standard was recently updated to address upper temperature limits, associated power controls, feedbacks and fail-safe requirements.
Chapter 9 of the 2018 International Building Code, which specifies fire protection and life safety systems, requires a number of unconditioned air spaces, inclusive of parking garages, loading docks, refrigerated warehouses and porte-cocheres, to be outfitted with automatic sprinkler systems. Installation of a wet-pipe fire sprinkler in unconditioned air spaces exposed to ambient temperatures below 40° F requires freeze protection, and Chromalox has developed the industry’s first third-party-certified fire sprinkler pipe freeze protection system for wet-pipe fire sprinkler systems, an attractive alternative to dedicated dry-pipe systems.
UL 515, the Standard for Electrical Resistance Trace Heating for Commercial Applications, was redacted in 2016 and accompanied by an addendum that addresses trace heating and associated control requirements for use in fire sprinkler and standpipe systems. The current standard, UL 515A, addresses operating temperature limits, control requirements and fail-safe requirements.
Upper temperature limits defined by UL 515A act to eliminate false alarms while emphasizing the need for energy efficiency improvements. Aboveground water-filled lines, main standpipes and risers exposed to ambient temperature below 40° F require a thermally insulated electric heat trace system that effectively maintains fluid temperature above 40° F.
Control system requirements include a mandate for backup power contact or types with a permanent, hard-wired power source. They need to provide audible or visual alarms along with fire control communication capabilities. A fail-safe mechanism with auto-restart capabilities is also required to ensure continuous monitoring and heating capabilities that reliably maintain fluid temperatures at or above 40° F.
Chromalox third-party certified fire sprinkler pipe freeze protection system
Chromalox’s fire sprinkler pipe freeze protection system is listed and approved to NFPA 13: 2019, IEEE 515.1 and UL 515A standards, which collectively define test, design, installation, maintenance and control requirements. It reliably maintains water-filled fire sprinkler system components at or above 40° F and is listed for use in ambient temperatures down to -40° F.
Complications in maintaining an even temperature profile in a wet-pipe fire sprinkler system are due to the inability to insulate sprinkler heads and other exposed system components. Concentrated heat tracing along these exposed sections of the fire suppression systems can lead to temperature spikes that have been known to trigger false alarms.
To address challenges with irregular temperature profiles, Chromalox designed a system with self-regulating (CPR) freeze protection cables, resistance temperature detector (RTD) temperature sensors, an advanced controller and an over-temperature protection device with auto-restart capabilities. The complete system has been tested in accordance with UL 515A and meets all current standards for fire sprinkler pipe freeze protection systems.
CPR freeze protection cables
CPR freeze protection cables provide concentrated heat output with respect to pipe temperature and can be cut to length. A self-regulating polymer core with variable output reduces hot-spots and increases energy efficiency. The cables are designed for circuits up to 660 ft long, feature a minimum bend radius of just 1 1/8 in and are available in several watt densities of 3, 5, 8 and 10 watts per foot.
IntelliTrace ITC-FS heat trace controller
The IntelliTrace ITC-FS single or double-circuit heat trace controller is designed for fire sprinkler pipe freeze protection systems and meets or exceeds test requirements defined by IEEE 515.1-2012. The device contains dedicated dry contacts for interfacing with the fire control panel, is permanently connected to the building systems power source and is designed for use with a Chromalox RTBC line-sensing thermostat for each powered circuit, which is an over-temperature protection device with auto-restart capabilities.
Feedback to the controller is provided by 100 Ohm platinum RTD sensor inputs. It is equipped with local audible and visual alarms while the supervisory signal transmits ground faults, sensor failures, high- or low-temperature alarms, loss of continuity, loss of power and controller failures to the fire alarm control panel.
The complete fire sprinkler pipe freeze protection system is listed and approved to current NFPA 13, IEEE 515.1 and UL 515A standards, although it is not intended for use with third-party controls, cabling or other third-party system components, with the exception of pipe insulation and waterproof jackets. System components are inclusive of the following:
• ITC-FS controller
• CPR freeze protection cable
• RTD sensors
• RTBC line-sensing thermostat (one per circuit)
• DL-series heat trace connection kits
Comparing wet-pipe vs. dry-pipe fire-suppression sprinkler systems
A dry-pipe system works analogous to a wet-pipe system, but instead of water-filled lines a pressurized gas is used to isolate the system. When a sprinkler head is activated, pressure is lost and a valve releases water into the lines.
Dry-pipe fire sprinkler systems carry numerous disadvantages as installation, maintenance and testing requirements are all complicated by an increased corrosion potential. Condensation and moisture content greatly increase the oxidation potential of a dry-pipe system and purging lines of moisture after a leak is detected or post full-flow trip testing can be both problematic and costly. They also carry a delayed response time and while the use of an inert gas like nitrogen lowers the corrosion potential, condensation and water capture points pose complications that can lead to corrosion, freezing and device malfunction.
Dry-pipe fire sprinkler system installations require a pitch of at least 0.5 in per 10 ft for branch lines and at least 0.25 in per 10 ft for mains. Auxiliary drain valves are installed in central locations and serviced regularly. These requirements increase the cost of installation.
Maintenance costs associated with a dry pipe system are also more substantial. Inspections need to be carried out more frequently to ensure no leaks are detected, that gas pressure is maintained and any amount of moisture content, due to either leaks or condensation, is effectively removed from the system.
Wet-pipe fire suppression sprinkler systems are regarded as the most reliable and economical fire suppression systems commercially available. Oxidation potential is greatly reduced, installation costs are lower and it is much easier to purge lines of gas than it is to remove any amount of moisture, as is required in a dry-pipe system. A wet-pipe system supported by Chromalox’s fire sprinkler pipe freeze protection system is not only more economical, but also has a longer life span, is simpler in design and has a faster response rate in the event of a fire.
The integrity and effectiveness of automatic fire sprinkler systems are addressed by the development of NFPA 13, IEEE 515.1 and UL 515A standards. In the case of wet-pipe fire sprinkler systems and standpipes in unconditioned air spaces subject to ambient temperature below 40° F, UL515 was recently redacted to address operating temperature limits, control requirements and fail-safe requirements for sprinkler pipe freeze protection systems.
When existing freeze protection systems on the market failed to address requirements of UL515A, vendors opted for an alternative solution: dry-pipe fire sprinkler systems. However, these systems carry several inherent disadvantages, including system complexity, high installation and maintenance costs, low design flexibility, lengthy response times and great corrosion potential.
Chromalox’s fire sprinkler pipe freeze protection system is third-party certified to the latest NFPA 13, IEEE 515.1 and UL 515A standards for use with wet-pipe fire sprinkler and standpipe systems. The system provides for installation cost reductions, eliminates fluid delivery delays and increases system reliability when compared to dry-pipe systems, while providing a longer service life and lower total cost of ownership.
To learn more about Chromalox’s heat trace solutions and how they can address your wet-pipe fire sprinkler applications, visit their website or contact them directly.