To help reduce the chance of freeze-ups, a primary objective is maintaining adequate building heat in all areas where water filled systems are present. This objective can be achieved through:
- Pre-season preparations
- Periodic cold weather inspections
- Special action plans when cold waves (or Artic blasts) are predicted
- Special precautions for extended idle periods
- Response plan for low building temperature conditions
When water-filled systems freeze, the formation of ice can develop into significant obstructions that can leave the systems impaired. For domestic systems, a freeze-up may be identified by a loss of water pressure or flow. For fire protection systems, the freeze-up may represent a hidden impairment that is not immediately apparent.
Water is unusual in that it expands when it freezes. Water that freezes within piping systems can impose significant loads that can eventually break pipes, valves, and fittings. This secondary impact can lead to further system impairments. Not only must the ice thaw, but repairs will be needed.
If temperatures moderate and ice plugs thaw before broken pipes are detected, a tertiary impact can develop as water escapes from the systems and damages the building and contents. At this stage, not only can the freeze-up impair and damage a water-filled system, but it can potentially magnify into wide spread property damage, business interruption, and irate tenants and customers.
A primary objective to help reduce freeze-ups is maintaining adequate building heat. A likely question will be what is adequate building heat?
As ice forms at 0°C (32°F), building temperature will certainly not be adequate if they are at or below this freezing threshold. So, what temperature is considered sufficient?
NFPA codes and standards use 4 degrees C (40 degrees F) as the threshold for an adequate building temperature. At this point, actions should be initiated to identify and correct the cause of the low building temperature condition.
Monitoring a building for a low temperature is a challenging effort. Three methods are typically used:
- Normal building occupancy
- Security patrols
- Electronic low building temperature supervision
Normal building occupancy is a simple and reliable approach to monitor a building during normal business hours. Of course, there may be some normally unoccupied areas that would require a special effort to maintain periodic human presence.
Outside of normal business hours, security patrols can maintain periodic human presence throughout an unoccupied building. Hourly patrols in accordance with NFPA 601 would be Zurich best practice.
With electronic supervision, room temperature supervisory devices would be provided as part of the building fire alarm system in accordance with NFPA 72. Room temperature supervisory devices initiate a supervisory signal when the temperature falls below 40C (400F). These devices are typically installed only at automatic sprinkler system risers. As such, the extent of coverage provided with these devices is typically quite limited.
Overall, there is no substitute for human presence, and few businesses provide human presence at all times. As a result, continuous monitoring of building temperature is a challenge. No doubt this explains a continuing experience with freeze-ups, and the importance of taking appropriate actions to prepare for cold weather, periodically conduct cold weather inspections, and have a special action plan when extreme cold weather is expected.
Guidance
The following guidance applies to buildings that are exposed to cold temperatures at any point during the year. Implement a plan to maintain adequate heat throughout the cold weather season. Make sure the plan includes the next series of items.
Before the cold weather season begins, have qualified persons conduct the following inspection and maintenance actions:
- Heating systems – Provide annual service
- Air-handling units – Verify dampers work and fans are controlled by thermostat for automatic shutdown in the event of freezing temperatures
- Non-freeze fire protection systems – Check air sources, air pressure levels, low point drains, and antifreeze solution in accordance with NFPA 25
- Insulating systems protecting water filled pipe – Verify coverings are intact
- Heat trace systems protecting water filled pipe – Verify system performance and supervision
- Building envelope – Verify windows and doors are functional, weather tight, and in good repair
- Fire alarm systems – Check building low temperature and sprinkler system air pressure supervisory devices in accordance with NFPA 25 and NFPA 72
- Correct any noted deficiencies before cold weather arrives
Some building spaces such as stairwells, lobby vestibules, elevator penthouses, above ceiling spaces, fire pump rooms and houses, and dry pipe valve closets, seem to have a greater exposure to freezing.
In preparation for cold weather these spaces should be reviewed. Consider actions such as:
- Installing thermometers to simplify periodic inspections. For above ceiling spaces, provide remote reading thermometers that allow temperature checks from floor level.
- Replacing wet-pipe sprinklers with non-freeze type systems in areas that are difficult to heat.
Once cold weather arrives, begin periodic inspections. Ideally, conduct periodic inspections on a daily basis using a form to record each inspection. If you don’t have a form, develop one to capture the following data:
- Building windows, doors, and walls are closed and weather tight
- Building temperature in each area including those with a greater exposure to freezing
- Heaters are working
- Air pressures in each dry-pipe or pre-action sprinkler systems
- Dry-pipe system low point drains that have been opened to remove accumulated water
- Water-filled pipe insulations are intact
- Water-filled pipe heat tracing systems are working
When extreme cold temperatures are forecast, recognize that unusually frigid conditions could overwhelm normally effective combinations of building heat and building insulation. Take time to implement a special action plan before the cold wave arrives including conducting a periodic cold weather inspection, safely increasing building heat to all areas, and overriding energy saving set-back thermostats or building management programs that may automatically reduce building temperatures during the cold wave.
When extended idle periods are planned during cold weather, recognize that the interruption of normal human presence during a long weekend or holiday period increases the potential that a freeze-up may occur. Implement special precautions to maintain periodic cold weather inspections, an awareness of weather forecasts, specifically cold waves, an availability of knowledgeable personnel to promptly respond to abnormal conditions.
Develop and implement a written procedure to respond to abnormal conditions identified during a periodic cold weather inspection. Whether it is a broken window, a heater failure, or low building temperature conditions, prompt action will be needed. For each condition listed on the cold weather inspection form, identify potential actions that may be appropriate. This may include a contractor contact list to expedite requests for heater repairs, glazing repairs, or sprinkler system service.
In conclusion, reducing the chance of freeze-ups depends upon maintaining adequate building heat in all areas where water filled systems are present. While this goal is easily stated, the ongoing freeze-ups experience demonstrates just how difficult it is to achieve this goal.
When disaster strikes, be prepared to implement a good communication strategy, maintain best loss prevention practices, and take appropriate actions to expedite restoration while avoiding further loss. Maintaining a strong commitment to a well managed response will provide the most direct route back to business as usual.
References
- NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems. Quincy, MA; NFPA, 2011. Print.
- NFPA 72, National Fire Alarm and Signaling Code. Quincy, MA; NFPA, 2010. Print.
- NFPA 601, Standard for Security Services in Fire Loss Prevention. Quincy, MA; NFPA, 2010. Print.
