The Fire Protection Obstacle Course Part 2: Five More “Gotchas” That Can Make or Break Your Project
by Mike Lehner, P.E.
This article is part of Wood Harbinger’s newsletter series.
In a previous edition of this newsletter, I introduced five “gotchas” related to fire protection systems that could wreak havoc on your project. This list, of course, is far from comprehensive, so I thought I’d follow up with a few more “gotchas” to watch out for. Many of these share the same theme of the others—communication and doing your homework.
The sprinkler valve room
Why is a valve room an issue? What is a “valve room?” for that matter?
The sprinkler valve room is where the main fire protection water supply enters the building and may include a backflow preventer and a sprinkler riser assembly for each fire sprinkler zone. Fire sprinkler zones range from 40,000 SF (extra hazard occupancy) to 52,000 SF (light hazard occupancy). Each riser can occupy a 36-inch square space with additional space in front for access. Add in a backflow preventer (which protects the potable water system) and you have some significant floor space requirements.
Imagine you have a large project, and only some general notes were added to the drawings to instruct the contractor to provide fire sprinkler protection. Then, after the project bids, the contractor sends a RFI and asks, “Where would you like the fire sprinkler room?”
You may ask,” What about the mechanical room? Can we use space in there for the valve room?”
The first problem with this statement is “mechanical room” and “space” in the same sentence. If you’ve ever seen a mechanical room, you know how crowded they can be! It’s a challenge in and of itself to optimally locate all the mechanical equipment that needs to go in this room. There is usually not enough space to add a backflow preventer and several sprinkler risers. In many jurisdictions, the fire marshal requires that sprinkler risers be in their own room.
Let’s say the fire marshal does allow the mechanical room scenario, and it looks like there might be enough room. Is it worth the risk to try to squeeze in there? In many cases, it’s just not workable. Now you have to go back to the architect to see if there’s any other space for your valve room. This may mean shrinking office, storage, or classroom space to meet fire protection needs, which could mean an unhappy owner. Adding on to this challenge, many jurisdictions require that the sprinkler valve room be on an outside wall and have its own access door. Depending on the building layout, this might be a difficult requirement to meet this late in the game.
Don’t let this happen! Discuss the requirements early in the design process and coordinate the sprinkler valve room location with the fire marshal and the project architect!
Standpipes
Standpipes enable the fire department to quickly extend fire hoses into the building without having to run additional fire hose in stairwells, long corridors, or other areas where they could be inconvenient or create an obstacle. Building code usually requires standpipes if the highest or lowest story floor level is more than 30-feet above or below the level where the fire department would access the building. In other words, four-story and taller buildings (and maybe some 3-story applications) will require standpipes.
There are some exceptions to this requirement, and code varies from jurisdiction to jurisdiction. As such, it’s important to verify whether standpipes are required for your specific building project. If you do need standpipes, they are usually located in the code-required building stairwells. This means coordination must happen with the project architect to ensure that the standpipe does not impede exit travel pathways in the stairwell.
Code also requires that standpipes be interconnected, which may require large pipe mains on the lowest floor. All of this can result in additional construction costs if not included early in design.
Special system requirements
There are many kinds of special fire extinguishing systems that come with their own unique design considerations. Examples include wet/dry chemical systems that are often used to protect kitchen hoods or other hazards, and clean agent systems to protect computer rooms and other sensitive spaces while mitigating water damage. Coordination with other disciplines is required with these special systems, for fire alarms, ventilation, floor space requirements, and room integrity for clean agent systems. Clean agent systems are not always considered sufficient fire protection by some jurisdictions, so it is important to contact the fire marshal to clarify the specific requirements.
There are also special building systems (for example, a dust collection system) that may require specific sprinkler protection or other fire protection features. Proper coordination from project onset is crucial to ensure that both the special fire protection system and the special building system it may be serving are designed to work together successfully.
Dry pipe system issues
Dry pipe systems are fire sprinkler systems that only fill with water when the system is activated. The piping is filled with compressed air until a sprinkler head is activated, which trips the valve and admits water into the system.
The first trap is knowing where to provide a dry pipe system. Basically, if the piping is subjected to any freezing conditions, then a dry pipe system is the right choice. This could include cold attics, exterior canopies, open garages, and freezer storage. In some locations, dry type sprinkler heads can be used to eliminate the need for a fully dry pipe system.
The second trap is making sure drain locations are coordinated so the system can be properly drained. Like many sprinkler systems, the fire protection engineer provides a performance-based design, which is completed by the contractor. However, the engineer needs to provide direction to the contractor and coordinate with the mechanical engineer to make sure the drain points are included. Dry piping must be sloped to drain and can cause other coordination issues for long runs of piping, in addition to long trip times, which can be problematic. Proper placement and orientation of the dry system is critical to a successful installation. Finally, coordinating where the dry pipe sprinkler system air compressor is located is critical as well. This is to ensure that it has power and it is not in a sensitive are where noise is undesirable.
General coordination
This category covers many items, including architecturally sensitive areas, working with other disciplines on pipe routing, and coordinating with the electrical engineer for fire alarm points. There are many instances where architectural constraints may prevent concealment of sprinkler piping. If this is not addressed until construction, it can be more expensive to “hide” the sprinkler piping. If no consideration is given to general pipe routing of sprinkler mains, the same issue could come up during construction. Nobody wants to see a sprinkler pipe pierce ductwork!
The fire alarm system monitors all sprinkler risers with a flow switch, and sprinkler valves with a tamper switch. It is important to coordinate with the electrical engineer to ensure that all of these devices are included, or additional cost and/or conduit routing issues will ensue after construction starts.
Fire protection design and construction can go pretty smoothly with the right coordination! Things can be a lot simpler when you’ve done your homework and communicated with project stakeholders and the architect/engineering team. Having a fire protection engineer in your court could help prevent some of these gotchas!