5-Minute Guide on Property Risk Management: 10 Steps to Winterize a Wet Pipe Sprinkler System
Intended Audience: Commercial Building Owners, Managers & Facility Maintenance Personnel.
The Problem:
Frozen water pipes are listed by The National Fire Protection Association as the 2nd leading cause of wet pipe fire sprinkler systems failures, after closed control valves.
Between 70 to 90% of the sprinkler systems in commercial buildings are wet pipe.
The percentage of wet pipe sprinkler systems will be lower in regions that experience low winter temperatures compared to more temperate regions.
When the water in piping freezes, it expands in volume by around 9% meaning that it may cause the pipes to rupture or leak.
Interior Temperature Thresholds for Wet Pipe Sprinkler Systems:
40°F is the NFPA minimum required indoor temperature for water in wet pipes with a possibility of freezing.
20°F is the temperature which water in metal piping can begin to freeze with prolonged exposure.
10°F is considered a high risk with pipes freezing within minutes rather than hours.
0°F is considered an extreme freezing hazard for wet pipe systems.
The Reasons Why Wet Pipe Sprinkler Systems Freeze in Winter:
The Lack of Winterization or Regular Maintenance.
Unheated Spaces in Attics, Basements, Crawl Spaces & Garages.
Inadequate or Missing Insulation.
HVAC System Failures Including Power Outages.
Interior Heating Temperatures Set Too Low or Turned Off.
Inadequate Sprinkler System Design.
Ways to Estimate Water Temperature In Wet Piping:
An immersion sensor, usually consisting of a tee fitting and a temperature probe is considered the most accurate and reliable.
Sensors mounted on the exterior of piping are usually cheaper and simpler to install, but less accurate than an immersion sensor.
Room thermometers are generally considered less accurate than either immersion or pipe exterior mounted sensors.
Thermal or infrared cameras are not a reliable means to measure temperature as the water blocks the infrared wavelengths needed for the camera to see through it.
Draining Water From the Sprinkler System Should Not be an Option:
A wet pipe sprinkler system cannot serve its intended purpose without water.
Draining the water can void the property insurance policy as it is considered as a fire system impairment.
It can cause the piping interior to corrode and accumulate rust at a faster rate.
Wet Pipe Sprinkler systems can have low points where the water cannot be completely drained.
Residual water left in the system can freeze.
Refilling a system too rapidly can cause a damaging water hammer effect.
10-Steps to Winterize a Wet Piping Sprinkler System:
Ensure that the sprinkler system is being maintained according to NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.
Confirm that all rooms serviced by the sprinkler system will be heated to at least 40°F at all times.
Verify that the building’s heating system is operating properly and dependably.
Inspect areas that are likely to freeze first such as attics, crawlspaces and basements for sprinkler heads and lines.
Closely inspect the sprinkler riser room for possible cold air leaks around doors, windows and pipe openings through walls.
Test the sprinkler main drain to ensure its serviceability and adequacy of water flow.
Determine that the exterior walls and opening are adequately sealed and insulated against cold air.
Confirm that there will be adequate building staffing levels or sprinkler system water line temperature monitoring during nights, weekends and holidays.
Train personnel on the importance of preventing the freezing of water in wet pipe systems.
Conduct at least weekly winter building walkthroughs with particular attention to thermostat settings, cold spots, water leaks and that the sprinkler control valves are in the correct position and adequately secured.
Key Takeaway:
Freezing in wet pipe sprinkler systems happens when cold air reaches the water inside the pipes at a faster rate than the building’s interior air can keep them warm.
About the Author:
Rob Brooks is the Loss Control Manager for Centurion Insurance Services in Charleston, West Virginia. He has over 40-years experience in his profession having worked for some of the leading insurance carriers and brokers. Rob has professional certifications in both human resource management (CHRS) and workers compensation (CWCP) from Michigan State University’s School of Human Resources & Labor Relations.
Rob can be reached at [email protected] or (606)434-0739.
Disclaimer:
This publication is intended for general educational purposes only, and not to be considered as business, financial or legal advice. Centurion Insurance Services and the writer makes no guarantees or warranties of any kind, express or implied, about the reliability, completeness or suitability of the information contained herein. Readers should consult with appropriate professionals before making any decisions based on the content of this newsletter. We will not be liable for any losses or damages arising from the use of the information provided.
