Help! Question on vertical space clearance between sprinkler deflector and AHUs

[Jcqa]

Hello everyone, appreciate it greatly if I can hear some opinions. A few years ago, when I was doing a paid student attachment with a HVAC supplier company, I helped to prepare AHU equipment schedules for building projects. In many of the schedules that I prepared for my company, I failed to add the height of AHU base frames(100mm) to the AHU heights since I did not realize at that time that I was supposed to include it. At that time, I did not consider it as important and did not bring it up with my mentor during my time there.

However, now that I'm working in the MEP field, I realize that the NFPA and my country's fire code have a spacing rule whereby there should be minimally an 18 inch vertical clearance between sprinklers and material below it. I'm very worried that this clearance of 100mm could be compromised if the contractors don't notice the mistakes and just install the AHU equipment while blindly following the AHU schedule dimensions without doing final measurements on site. As I'm still new, I'm still not sure how the whole flow of projects go. From what I see, the 18 inch rule is to ensure the sprinkler discharge pattern works the way it's supposed to be and I keep worrying over the scenario that if a fire happens to break out at the AHU room/equipment room/wherever the AHUs are installed, the sprinkler performance will be compromised and might have dire consequences to property and lives.

Can any fire safety experts advice if this is a legit concern or if I'm overworrying? Is there usually a very safe, large clearance between AHUs and sprinklers in the AHU locations? This is for many projects and while I did tell my mentor much later on after leaving the company that I may have missed out on including the base frame heights in some of the projects, I don't think he is aware of the fire requirements as it is a HVAC vendor, and hence not familiar with fire code/NFPA. ANd I am afraid some of the projects might have already been completed. If anyone has the expertise, please help to advice if there are any real dangers and what I should do! This has been stressming me a lot and I don't wish to have my mistakes put anyone in danger.

 

[cdafd]

My non engineer answer

There are a few variables involved, with fire sprinkler placement.

There is not one general statement, that can be given.

Truthfully, the fire sprinkler installing company should be looking at this, and adjusting.

Now if you are trying to avoid be charged for moving sprinklers, because of your work, get with the fire sprinkler company on the job, and work with them, to avoid obstructions.

 

[nwn_2020]

Don't worry about it. This is what inspections are for before AHJ give the green light for occupying buildings. If anything, it should be the sprinkler installer having a final check and making amendments according to site conditions.