What coordination questions should you ask mechanical?
Let’s cover things we need to think about when we’re coordinating with mechanical systems, and mechanical system designers. I’m looking at this from a consultant’s perspective, but just about all of these coordination items are relevant when we prepare shop drawings as well.
For sprinkler design across the world, there are different requirements for the consulting engineer. Though fully-designed systems are required for permitting in many different countries, it's also common that performance specifications from the consulting engineer outline the criteria for the sprinkler system.
With performance specifications, we typically do not go into arrangement detail like a full sprinkler design would. This matters when it comes to coordination with mechanical systems.
LACK OF COORDINATION
Arrangement of sprinkler mains in reference to ductwork can be the single most common cause of construction interference because of lack of coordination. Ceiling space is valuable and coordinating with the discipline that takes up the largest volume within a ceiling space is critical.
One cause of lack of coordination can be caused by performance specifications not detailing where mains should be located in reference to other engineered systems like mechanical ductwork. If the pipe routing is not caught during the contractor shop drawing review, the systems can be in conflict with one another and cause issues for the installers in the field. This can cause construction delays and change orders which never look good for the entire design team or construction team. To avoid construction issues here are some coordinating questions when working with Mechanical Engineers.
WHERE ARE DUCTS LOCATED?
1 - Where are your ducts located? Usually ductwork plans indicate the relative position of ductwork, but they frequently do not show the height of where the ductwork is intended to go. Can sprinkler pipe be routed consistently underneath ductwork? If the ducts are at least 10-12 inches above the ceiling level, and we’re in a non-seismic area, then there may be a zone that sprinkler pipe can route under. If that’s not the case, is there room to route pipe above ductwork? Many times, Mechanical Engineers don’t think about other systems, like sprinkler, and allocating a zone or at least some space for sprinkler pipe to run. This question helps us in fire protection at least get a sense on where the ductwork is supposed to go, so that we can try to avoid it.
2 - Where are your ducts greater than 48 inches (1.2 meters) wide? This affects open-structure areas. If ductwork is more than 48-inches wide, or if there is a bank of ductwork that’s more than 48-inches wide, then they’ll likely be obstructions to the sprinklers, and we’ll need protection beneath these obstructions.
3 - Will the space be heated over 40 degrees Fahrenheit (or 4.4 degrees Celsius)? This affects whether we can keep a wet system in a space, or if we need to look into other solutions like use of dry sprinklers, dry-pipe systems, or alternatives like antifreeze.
4 - Who is providing the incoming water service? Is it a combined system, where fire and domestic water will be split inside the building or will the water service be split outside the building, or will there be two separate taps? We want to coordinate this so the contractor understands a clear scope of work, and we don’t cause confusion later on.
5 - Do you have a fire pump room or a water service entrance room? A fire pump room requires a number of special accommodations under NFPA 20, like a fire barrier, a dedicated space for fire protection equipment without storage or non-water systems, heat, cooling, and possibly ventilation, exterior access, and more.
6 - Have we coordinated the mechanical room layout to provide access to all of our equipment? Accessibility usually means at least 3-ft in front of our operable equipment. Can we fit everything we need for the project? If we have a horizontal backflow preventer or multiple zones, we may need some significant space horizontally. Is that accommodated? Are there conflicts with other equipment?
7 – Are there clearances that we need to work around? Above ceiling spaces, mechanical units such as VAV (variable air volume) units have needly access requirements. We want to be sure we know where mechanical units are going to be located, so that we don’t have to run pipe right through the access space, or, you know, the unit itself.
8 – What about fans, unit heaters, or other equipment? Are there (Big Ass) Fans that we need to coordinate sprinklers with? In walk-in coolers and freezers, there are often exposed cooling units that cause obstructions for sprinklers. These often don’t show up on mechanical plans, but if they’re coordinated early the mechanical engineer can provide some direction. What about unit heaters? Are there heaters that the sprinkler contractor needs to know about to coordinate sprinkler temperatures? All good questions to ask.
COORDINATION IS KEY
These are only a few of the questions you may have in addition to project specific questions that need to be coordinated with the mechanical and/or plumbing engineer. Don't be afraid to ask questions that may be simple like coordinating access because it may end up being an oversight that could be costly later.
These little mistakes lead for challenging maintenance and operation of the life safety systems.
I've seen many different examples of performance specification projects that the sprinkler contractor is the first person on site and begins installing the sprinkler system prior to the mechanical contractor installing their ductwork. Many different times, once the ductwork is routed they find all the conflicts all the areas that the sprinkler piping has been installed that prevent the ductwork from following their design path. This is something that can be prevented if careful coordination during design or even during shop drawing review occurs across multiple disciplines.
Never design a sprinkler system or review a sprinkler system with your blinders on. There's always construction issues and the preventable ones are the problems that owners remember, even contractors remember. This is why going the little extra distance during design, even if you're providing a performance specification and you're not providing a full design, you coordinate with mechanical systems to prevent conflicts in the field.
The other reason you want to coordinate with Mechanical Engineers is to ensure that your sprinkler system is in an environment that is not prone to freezing and maintaining the temperature within the space that your sprinkler piping will be routed or for you to design a sprinkler system to accommodate for freezing conditions.
So coordinating questions for mechanical should include the environment temperature, ability to maintain equipment in the future, location of mechanical equipment in relationship to system valves that need to be maintained, ductwork greater than 48 inches because it poses a potential obstruction to sprinklers, coordinating incoming water services in which trade is going to take responsibility and to what point, and verifying contractor shop drawings or your full design with a multidiscipline review to make sure that your pipe routing coordinates with mechanical systems routing. if this coordination can be done early, you'll see fewer conflicts in the field and smoother installation of your design.
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