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Mar 1, 2021

It’s the first solocast episode of Fire Code Tech! In this episode, we talk about the codes and standards involving duct detectors. We discuss how to determine whether duct detectors are needed, what codes and standards may be involved, pro tips and lessons learned from an FPE.

If you like these episodes, be sure to check out for the continuation of the Duct Detectors episode! You can expect these solocast episodes to be released twice a month.



Hello. Welcome to the solo cast of fire code tech in these episodes. It's just gonna be me, your host, Gus Gagliardi. There's gonna be a range of topics, but I'm gonna talk about like specific technologies, installation standards, codes, and how they work as well as some other interesting topics that don't neatly.

Inside of the context of a normal interview. So this is the first solo cast, and I just wanna give everybody an update on what's been going on with the podcast, how I've been doing we're coming up on our first year with fire code tech. And I'm really excited because there's been so much growth and good feedback from the community.

I got my PE last October, I had passed almost a year before last October in acquiring my experience and. In the application process, uh, it took almost another year for me to get the application. I don't know when this episode will come out, but I have some really stellar guests coming up soon. Couple professors that I have been waiting to talk to as well as some.

Really interesting guests from the, um, fire and line safety industry. So I'm excited to share those. Anyways, let's get to the episode content for the solo cast. In this episode, we're gonna be talking about duct detectors. I wanted to talk about duct detectors because. I always sense, a lot of confusion about them generally from mechanical engineers or from also fire protection engineers.

A lot of times we'll get it mixed up duct detectors. So I wanted to narrow in on this specific technology and talk about the codes and standards surrounding it. Some of the common. Pro tips for, um, dealing with some of these devices. Yeah. So I just wanted to explore the topic. Let's get into it by the way.

If you're enjoying these episodes, you can go to code tech, and for the price of a cup of coffee, you can get an extra two of these episodes a month. You'll be supporting the podcast and allowing me to do more and put out more content. So, um, go sign up if this is something you're interested in.

So with duct detectors, it's a good starting place. One of my mentors lean always, anytime we talk about a, a code or a topic, she says, um, you know, gotta start. The applicable codes and standards and what those look like. So if you're in the United States, that's probably a good preface for everything.

Almost everything I put out. This is through the lens of somebody who's working in the construction industry in the us. If you're in the United States and you're working with the international, uh, family of codes, the international building code and, uh, you know, international mechanical code, et cetera, you're going to be using international mechanical code.

Um, by and large to determine when and where you need to locate duct detectors. I'll go over the code section a little bit, just as a baseline at anytime you are using the international mechanical code, unless you get into a, um, air handling unit with a particularly large CFM that it's rated for that.

You're just gonna be putting duct detectors in the return side. So add this caveat because. There, if you are working on government jobs, like, uh, the company I work for works on a number of government jobs. And so if you're working on a job that complies with UFC, you are going to be using NFPA 90 a also that means that you're gonna be locating your duct detector in the supply side.

Duct. That's a common misconception that I see that trips people up, cuz in some instances, if you're, you know, using NF 90 a and the international mechanical code, you can get tripped up. So let's start out with the code section in the international mechanical code. I'm using the 2 20 15 version. We can just start out with, uh, 6 0 6 0.2 in IMC.

Chapter six is duck systems, um, 6 0 6 0.2 is where required. It says smoke detectors shall be installed where indicated in sections 6 0 6 0.2 0.1 through 6 0 6 0.2 0.3. Basically there is a list of conditions in which, you know, the, if you meet these conditions, then you will be required to have a duct detector in your, um, H V a C system.

And to add onto that, there are some exceptions in which you can kind of put a caveat on, you know, the requirement for the need of a duct detector. So 6 0 6 0.2 0.1 says return error systems and the passages smoke detectors shall be installed in the return error systems with the design capacity greater than 2000 CFM.

This is usually what everybody remembers. 2000 CFM is the threshold. And, you know, but they don't quite remember where or how these duct detectors are supposed to be located. And in the passage goes on to describe this a little bit more. It says in the return air, duct plenum, upstream of any filters, exhaust air connections, outdoor air connections, or decontamination equipment and appliances, you know, a very powerful exception is right below.

And then basically states that, you know, smoke air smoke detectors are not required in the return air where all portions of the building serve by the air distribution system are protected by area smoke. Connected to the fire alarm system in accordance with the IFFC the area smoke detection system shall comply with section 6 0 6 0.4.

There's not too many instances in the vanilla, uh, building code in which you need area smoke detection. This is one of those instances. I am not a huge fan of area smoke detection, but there are situations in which it can't be avoided due to ceiling plenum height, or, you know, uh, physical construction of a mechanical unit.

There can be situations in which. You know, you can't physically get a duct detector in a unit or in a, a return duct. So in some instances, there are no ways to get around having area smoke detection. When you have a, a system, a H V a C system that has the design capacity greater than 2000 CFM. And. You know, is not separated.

Uh, if you forget where this is located, you know, always remember international mechanical code, and then if you have a searchable document, I would, uh, always search detector and usually you can get to 6 0 6 pretty fast. So the other most common, um, exception to the rule of when you need smoke detectors, I missed.

Up at the top, but you know, it says smoke detectors shall not be required where air distribution systems are incapable of spreading smoke beyond the enclosing walls, floors, ceilings of the room or space in which the smoke is generated. This is a great exception. You know, if you have a large unit that is just, um, dumping air into a space, like a big warehouse space or, um, you know, for the company that I work for, we have, um, you know, hangers in which we.

Dumping large volumes of air, but it's just serving one space. You don't need a duct detector. However, I will say, as a cautionary tale, there are jurisdictions that don't recognize this provision. You know, I was working in California on a job late in the design period. I got bit on, you know, not having, uh, duct detectors in.

That would normally be omitted with this provision. So it's, it's worth noting that, you know, check your local ordinances. Um, if you're in California, of course, you can just kind of throw the standard international mechanical code out the door and you need to read the code. Like you've never, you know, designed a system specific system application before.

It's worth noting that duct detector is a supervisory signal. So this is not an alarm condition. There is some really interesting information about the supervision condition for duct detectors and 6 0 6 0.4 0.1. Says the duct smoke detector shall be connected to a fire alarm system where a fire alarm is required by 9 0 7 0.2 of the international fire code.

So 9 0 7 in the building code and in the fire code are the fire alarm chapters. So basically this point, you. To, um, how you determine where a fire alarm system is required. And, and so this code section is saying, if you are required to, you know, have a fire alarm system and you have a duct detector, you need to, you know, have a supervisory condition.

When the duct detector is activated. So, and then there's some interesting exceptions below reading. This it's kind of interesting. It says, uh, the supervisory signal at a constantly attended location is not required where the duct smoke detector activates the buildings, alarm indicating appliances. Uh, you have never used this provision.

That's kind of interesting. Generally, if you have a fire alarm system, that's monitored. And so I guess this is a way you could short circuit that and then, uh, exception number two is in, occupancy's not required to be equipped with fire alarm system, actuation of a smoke detector shall beta visible and audible signal in an approved location.

Duct smoke detection, trouble conditions shall activate visible or audible signal and approved location shall be identified as a duct detector trouble. So basically this is another unique provision for a building that is not required to have a fire alarm system. But is required by the IMC to have a duct detector.

Yeah. I imagine there's some specific use cases in which you would see this, but I've not had, uh, any experience with buildings, um, with this unique configuration. Usually if the building's that small, they're not gonna require that much air. Yeah. I guess there's some unique cases which I might not be aware of, but so that wraps up our first solo cast episode of fire code tech.

Um, really excited about these. Don't forget. If you like these, and you wanna hear a couple more of these a month, go check out code tech. The first episode on the Patreon is another, uh, similar length of exposition on duct detectors. So if you enjoyed this little dive into duct detectors, then there's more of that where you can find on, uh, code tech.

So check it. Thanks for listening. Everybody. Be sure to share the episode with a friend, if you enjoyed it, don't forget that fire protection and life safety is serious business. The views and opinions expressed on this podcast are by no means a professional consultation or a codes and standards interpretation.

Be sure to contact a licensed professional. If you are getting involved with fire protection and or life safety. Thanks again. And we'll see you next time.