How to prevent fire sprinkler freeze-ups

December 6, 2012 - The first thing anyone with a fire sprinkler system should understand is that a little maintenance goes a long way toward keeping them functioning throughout the winter. The second thing they should understand is that they are responsible for the maintenance.

Entire systems have been damaged and replaced because the system's owner didn't spend five minutes maintaining a low point drain. When it comes to winter freeze-ups, the majority of cases ironically involve dry pipe systems designed for cold applications.

Dry pipe systems mechanically withhold water from the sprinkler system with pressurized air. The air supplied by a compressor contains a certain amount of moisture. Eventually the temperature inside the system drops and the water condenses. The pipe on dry systems is required to pitch back toward the drain so the condensation does not accumulate in cold areas.

When pitching pipe back to the system drain is not possible, a low point drain is installed in pipe sections holding trapped water. These sections accumulate enough water to freeze. When water freezes, it expands up to 10 percent in volume, which causes the pipes to snap. Such a break results in an air leak that trips the valve, allowing the system to fill with water. This results in costly damage and even more costly interruptions to business operations.

To avoid delays, following a small regimen of maintenance checks during peak freeze-up periods is as simple as it is valuable:

• Provide additional pipe insulation in unheated areas in which the system is located. Insulation helps block the flow of cold air from finding its way into pipe chases and soffits that focus the flow onto sprinkler piping and accelerate freezing.
• Install water flow alarms to alert users that water is flowing in the system and temperature signaling devices to warn users of potential freezing conditions.
• Drain all water and condensation from auxiliary drains and low points as often as necessary.
• Check pressures daily during cold weather, especially at night when temperatures are lowest.
• Install a desiccant dryer in the air line to help absorb moisture before the air enters the system. You can also transfer air from a chilled environment where relative humidity is naturally low.

Though United States Alliance Fire Protection (USAFP) encourages owners to perform regular system maintenance, the services detailed here are also available through USAFP. Contact your representative for more details.

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