Flexibility in fire-safety system design improves cold-weather performance

International Fire Protection recently took the opportunity to speak with Daniel Wake to explore the impact freezing conditions can have on fire-protection systems and how system design and product selection can help mitigate cold-weather challenges.

Experts around the world are predicting that the 2020–21 winter will be a relatively mild one for Europe and most of the United States, with only western Canada and the north-west United States likely to see colder-than-normal temperatures. Even with more mild winters, the freeze line in the United States has dropped as low as Dallas, requiring precautionary measures in the event of cold snaps. Freezing temperatures can place fire-protection systems at risk, rendering them useless for life safety, and likely to cause extensive property damage with expensive clean up. Designing systems with the correct length dry-barrel sprinklers and installing dry systems with the correct piping pitch can minimize these effects.

International Fire Protection Why is it important for designers to account for freezing conditions in their system designs?

Daniel Wake Below freezing temperatures can have adverse effects on various types of infrastructure, but they are particularly concerning for fire-protection systems because a frozen sprinkler system will impair the functionality. Managing the effects of cold temperatures on fire-protection systems is vitally important. When frozen pipes impair a system, not only is life safety in jeopardy but owners are also responsible for costly interim measures like fire watch and emergent repairs to the fire-protection system, let alone possible property damage. One way of mitigating a freeze-up is by installing the correct length dry-barrel sprinklers. These sprinklers allow an extension from wet systems into cold environments through a design that has the sprinkler seal at the connection point to the system, in a conditioned area, rather than at the sprinkler frame. The sprinkler is still activated in the same method as a traditional sprinkler, with the internal mechanism allowing water to flow through the barrel and across the frame and deflector. The sprinkler length is based on the lowest possible outside temperatures in conjunction with ‘exposed’ barrel length in the freeze protected space. Sizing correctly will greatly reduce the possibility for ‘localized freezing’ at the connection to the wet system.

International Fire Protection How and why do freeze-ups occur?

Daniel Wake A freeze-up can happen when wet pipes, or connections to wet systems, are placed too close to an exterior wall, when there is incorrect insulation protection, or when they are placed in a climate-controlled space that is not being properly maintained. Not all failures are necessarily the result of incorrect installation. For example, during the winter holidays, it is normal for dormitories and residence halls to be empty. When students and other residents leave for extended periods of time, they often do so without setting their thermostat to the right temperature – sometimes turning the heat down in their living spaces to reduce their energy bills. In situations like these, ‘exposed’ dry sprinkler lengths cannot separate freezing temperatures from the wet piping, and therefore are more likely to fail, leading to extensive damage and costly repairs as well as the replacement of lost property.

International Fire Protection In order to adhere to minimum standards for dry sprinklers and ensure system integrity, designers have added challenges that they need to accommodate for in their design. Can you explain some of these?

Daniel Wake Many different buildings require exterior sprinkler protection. One of the easiest ways to provide this protection, and ensure the system is protected from extreme temperatures is to use dry-barrelled sprinklers. Dry-barrel sprinklers are measured and manufactured in different lengths based on the exposure temperatures and length in conditioned areas described above.

One of the reasons traditional fire-protection systems freeze is that they often are installed along an exterior wall. To protect the pipes from freezing, designers initiated the use of soffits to house longer sprinkler barrel lengths so wet piping could be run in space that was heated. This prevents wet piping from freezing, but it introduces design and construction challenges. Soffits can be bulky, and they require more labour and more material to build, which makes them relatively costly.

Another solution to reduce the impact of freezing conditions on sprinkler systems is to use dry-sprinkler piping with dry sprinklers. While eliminating the water-filled piping, dry-sprinkler systems still present the installation challenges seen with traditional dry sprinklers. Inherent installation difficulties, such as multiple complex measurements and coordination between different trades, can lead to measurement errors, multiple lead time delays and additional expenses – all of which will negatively affect a project’s budget and timeline.

Fixing a frozen fire-suppression system can be quite difficult, and safeguards need to be in place to protect people and property until the system is back up and running. That usually means dedicating a team to watch for fires until the system is working again. The innovation of flexible barrel dry sprinklers allows sprinkler installers to maintain the correct length and appease architects by flexing or bending the sprinkler in the existing wall and ceiling cavities. This technology allows for compliant sprinkler installations while maintaining the desired look for a room.

International Fire Protection Are there better freeze-protection system designs?

Daniel Wake One proven alternative to these approaches is to combine flexible fitting technology with dry-sprinkler technology. With the ability to bend flexible dry sprinklers, installers can keep water farther away from freezing conditions by holding it deeper within the wall, eliminating the risk of frozen and burst pipes.

With a 2-inch bend radius, Victaulic’s flexible dry sprinklers contain no loose parts to complicate installation and can be easily connected to a branch line with a branch line swivel nut. For external areas that need freeze protection, VicFlex^™ dry sprinklers can connect to the automatic sprinkler system and then be flexed through an exterior wall or covered balcony.

International Fire Protection What does the future of freeze protection look like?

Daniel Wake The unique characteristics of flexible technology enable simple installation in conditions where installing a traditional system is fraught with difficulty. Flexible systems can be positioned so they are less prone to freezing in cold weather, increasing safety, reliability and performance. They also are easy to maintain, which means making repairs is minimally disruptive.

Flexible technology frees designers from the strict confines of traditional systems and facilitates creative problem-solving. Developing new ways to use the technology is limited only by the ingenuity of the engineer. That means there are many undiscovered applications, and there is enormous opportunity for expanding its use. New product development has the potential to give finite answers on accounting for freeze protection. With the development of new products and methodologies, engineers can have consistent solutions to accounting for freeze protection, by standardizing lengths of dry sprinklers, eliminating soffits in townhomes and even using integrated seals in cold storage to ensure a fully insulated sprinkler line.

For more information, go to www.victaulic.com