AMCA Insite Offers A One-Hour Firefighting Training Program To Teach About Positive Pressure Ventilation

This one-hour AMCA (the Air Movement and Control Association) insite™ Webinar Series covers the evolution of PPVs and AMCA 240 certification, along with ventilation principles, including entrained airflow and back pressure factors.


The broadcast is now starting. All attendees are in listen only mode. Hello everyone. Welcome to today’s AMCA insight webinar on positive pressure, ventilators, PPV, and AMCA 240 updates. I am Lisa Cherney, the education manager for AMCA international, and I will serve as the moderator of today’s webinar.

Before we get going with our few housekeeping notes, there is one special announcement I’d like to share with the audience. AMCA is hosting its annual idea exchange meeting. It will be virtual this year. It’s being held on April 13th. It is a half-day meeting, and the topic is the strength of impact, innovate, involve, and ignite. Details and registration for this half-day virtual event can be found at We invite you to join us.

We have fabulous speakers lined up. We have great topics to address, especially in this era of phenomenal change that we’ve all been going through. We have great ideas that we want to communicate back and forth. Please go to our website and check that out.

Quick introductions and guidelines.

The audience is muted during the webinar. Questions can be submitted at any time for our speaker via the control panel on your screen. If you go to the questions box, type in your question and hit send, we will address all of those at the end of the program. The webinar today is being recorded and that recording will be available within 24 hours on the AMCA website.

If you are interested in earning PDH credit for today, please remember that you must stay on the program for its entirety, and you must also complete the evaluation that will be sent to you after the conclusion. Again, to submit questions, please use your control panel and we will get to those at the end of the program.

In addition to any questions that people submitted in advance, on the registration form, PDH credit is being made available through AMCA International’s involvement with our CEP. We have met the standards and requirements of our CEP and the certificate of completion will be sent to everyone within 30 days of the end of this program.

Content today is not being endorsed or approved by our CEP and a quick disclaimer that the information in this webinar today, is provided by AMCA as an educational service. Only it is not intended to serve as professional engineering or manufacturing advice. The views and opinions expressed are entirely those of the speaker and do not necessarily represent the views of AMCA international.

So, when making this activity available to members and other professionals, we are not endorsing, sponsoring, or recommending a particular company product or application. Under no circumstances, including negligence shall K international, be liable for damages arising out of any parties, reliance upon, or use of the content contained in the web.

The program is copyrighted by AMCA international. So, reproduction, distribution, or use of the materials without written permission prohibited.

So, the boring stuff is over. Let’s get to the fun part of today’s program. Our presenter today is Kyle Weinmeister. He is the international sales director for an AMCA member company.

Kyle has a bachelor’s degree in mechanical engineering. He has an extensive background in business manufacturing, research and development production, and customer satisfaction programs. He has two years of volunteer firefighter experience. He brings a very specific and unique perspective to today’s program.

With that, I will turn the program over to Kyle.

Thank you, Lisa. Good morning, everyone, evening to some. Thank you for joining us with this webinar. Looking here we have four principles that we’re going to try and home in on. By the end of the presentation, you should be able to explain and understand what entrained or induced airflow is.

Explain and understand what backpressure is. Describe how and why. AMCA 240 benefits firefighters and identify AMCA certified PPV on the anchor website.

With that, we’ll start the presentation. I’m going a little too fast already. I’d like to start off with a brief history of firefighting ventilation to give us some context as to what the AMCA 240 does for firefighters and why it was created.

So, before PPVs, there were negative-pressure ventilators. You can see a couple of examples on the right here. In the ’40s and the ’50s, firefighters began repurposing boat and airplane propellers as permanent equipment to evacuate smoke from buildings. They were difficult to set up.

You had to prop them up on windows and find a way to set them indoors. They were just generally a little difficult to handle. They were also often electrically supplied, which produced more tripping hazards as generators were strewn out to supply these ejectors with power. Then in the 1970s, Controlled Airstreams began repurposing some movie production ventilators for use on the fire ground.

So, you can imagine one of those movie scenes with their hair blowing in the wind. The firefighting industry actually got that idea from the movie industry.

It took a while for the adoption of PPVs to really grab hold. It began in the west. Then by the 1990s, it had been gradually moving through the US. By the mid to late 1990s, nearly all US departments were training on PPV tactics. There were some major benefits, one being the setback distance. As you can see in the bottom right picture, the fan was not directly flush with the doorway.

So, you had some room to work. It also benefited the airflow by including entrained air. Another benefit was it was faster and easier to set up. You could roll the fan to the scene, set it where you would like it, start it and leave it. It wasn’t without skepticism that PPVs took hold early on, there were ideas that you would feed the fire with one of the three components of a triangle, which has now become a tetrahedron in the fire service on the upper right-hand corner.

You can see the tetrahedron and oxygen being the part that PPVs would enhance through this skepticism fire services have realized that it’s very important to have water on the fire and a flow tap, flow path established before beginning the ventilation.

In the early days, the idea was to seal a doorway. You would take a PPV and position it until bi-directional flow was inhibited. As you can see on the right. I move my cursor here so I can see what we’re talking about on the right. We have a picture that explains bi-directional flow on the top. You have the hot gases and, in this case, even flames coming out of the top portion of a doorway, a neutral plane.

So, the neutral plane here in the center and then fresh, cool air coming in low. As you can imagine this front firefighter, he’s feeling the heat. His helmet is toasty because the hot gases from the fire are coming out of the structure on top. This why the firefighter in the rear is staying low.

Later, it was found that steam conditioners could improve airflow. They stopped trying to preventing bi-directional airflow, which was to some degree inevitable and larger structures. Instead, the idea was to push through in the bottom half of the structure. This created a more effective airflow.

It also aided in ventilation through complex structures, created a higher pressure within the structure that allowed the smoke to be pushed through to the exit. It also allowed farther setback distances with sealed doorways and round guards. Typical setback distances were about one doorway or one door length away.

You can imagine six, seven, eight feet. With these new Airstream conditioners. That distance was extended up to 15, 16, 17 feet to allow more room for the firefighters to work at the entrance of the structure.

Shortly after the PPVs were being introduced, there were concerns of firefighters getting higher than normal rates of cancer. They started measuring carbon monoxide levels to be higher than normal or higher than allowable during the overhaul stage. The overhaul stage is when the main fire is out and you’re searching through to make sure that all the little fires are put out within the structure.

Ideally, you only show up to a fire once as a firefighter. It’s not ideal to have to show up twice to the same place or sometimes even three times, but. Fires have a funny way of hiding inside walls inside addicts. So, the overhaul stage has meant to prevent any kind of flame up after. So, during this time, firefighters were measuring high carbon monoxide levels and therefore found that gas PPVs and gas ventilators were contributing to this. Electrification still continues to this day for benefits outside of low emissions. They produce much less noise and there is less maintenance.

In the mid to late 2000s, we started seeing battery PPVs coming onto the scene. For a long time, they were not usable. The weight was too high. They were bulky. They weren’t reliable. The runtime was very small. The addition of lithium-ion battery technology really changed the reliability, first of all, but also the size of what these PPVs are and the amount of weight. As you can see on the right, it’s fairly simple for a single firefighter to carry a PPV on their shoulder up a stairwell, or even just slide them along the stairs.

Nowadays, battery PPVs are generally accepted for certain applications.

This slide is meant to reiterate that it’s important to stay current. A lot of these tactics are constantly changing. One good example of that is the fire development curve to the right. You’ll see that in the past, firefighters were taught through the four stages of a fire. It’s now understood that many of the structures are experiencing something closer to the bottom picture where the fire has its ventilation limited.

Then when the fire department opens a door, vents, breaks a window, whatever it may be, they see an extreme rise in temperature, a very quick rise in temperature. Then this illustration over to the left here is from Paul Combs. He’s a former firefighter who does really good work with portraying a firefighters view and hitting home. Some of these, some of these ideas.

Now I’d like to transition into the AMCA 240 standard. AMCA has created a video to promote the AMCA 240 standard. We’re going to use that as an introduction into the next part of this presentation.

Thank you, Lisa. So hopefully that gives you guys a brief overview of AMCA 240. I’d like to go into a little bit more detail on each of those. So, in the beginning, why was the 240 created? So, in the eighties and the nineties, there was a wild west era for approaching airflow performance of PPVs.

What was created was a positive feedback loop. What happened is manufacturers’ self-reported airflows were elevated through different methods. Fire departments would then receive that information from manufacturers. Demand or specify the requirements of their air flows, which in turn made other manufacturers match those report air flows.

 was negative for everybody. Really. It was, it was a deteriorating situation. So, something had to be done. So, in 1996 a group of manufacturers came together and came to AMCA and said, we need to create this standard. We’re having these issues. I think you guys are the right partners and have the scientific background on how to make it happen.

So, what they did is they created the AMCA 240 standard, which included entrained air

96’ for a little context with the first year that Calvin and Hobbs didn’t actually produce anything, but just started selling everything. So, yeah. This is a fun little cartoon there.

So, what is the AMCA240? 210 was the base that 240 was built off. 210 you can see over here on the left side, on the outlet of the fan, you can see that it’s sealed. Through that, you have a curve generated. The problem with PPVs is you don’t have that seal. There is no exhaust seal. So, what they came up with is here on the right.

You can see that there’s a setback distance from the doorway to the PPV. There’s a tilt that says where that PPV is pointed, and this allows the entrained air to be measured

well, behind that wall, the doorway. This is what we’re looking at here on the left is called a nozzle array. It allows AMCA to precisely measure the airflow going through the doorway. It’s a very accurate, repeatable way to measure airflow it’s used in high-rise building’s HVAC systems. It’s really the standard on how to make airflow measurements on the right.

You’ll see the diagram within AMCA 240 standard here. You see the fan that’s placed at a setback distance of S with a tilt of over, been a school for too long, maybe that’s fee or theta, and a height of H. Here in this plane is where you would see the doorway. You effectively have a large room to settle the air so that laminar airflow can be measured.

The nozzle array seen here on the left, another large room, and then a variable exhaust system. The variable exhaust system pulls air through this chamber to allow variable back pressures. It’s what makes the curve and allows AMCA to measure accurately at zero backpressure. Hmm.

So, what is backpressure here? We have a little bit more simplified drawing of the AMCA 240 setup. That pressure is the difference in pressure between the inside and outside of the doorway. It’s what reduces and increases airflow. So as backpressure increases, airflow will decrease as backpressure decreases airflow will increase.

That’s what this fan is doing is changing its speed to pull air at different airflows in effect this back pressure in this chamber here. So why was zero back pressure chosen? In 1996, there was little research available, and an exact number was not known. Continuing research shows the zero back pressure is actually pretty common on the fire ground, especially when ventilation begins.

So, following the water on the fire and a flow path or the exhaust opening establish. Negative pressures can be, can be realistic. Your zero back pressures are also realistic.

Next, we’ll look at entrained or induced airflow. Entrained airflow in the video described is the airflow that does not go through the shroud. However, it is pulled in through the doorway. This effect comes from a law in fluids from Bernoulli’s equation. It’s that faster air has a lower pressure and slower air has higher pressure.

Firefighters might experience this through hydraulic venting. So, as you can see in the bottom left corner, someone’s hydraulically venting through a window. The airflow generated from hydraulic venting is entrained airflow. By the water, carrying some air particles or some air through that, a window opening, whatever it may be, it’s pulling other air with it.

That’s the concept of entrained air. There’s a balance on the setback distance on how to get effective air through the doorway while maximizing the entrained air. Certain tests have found that roughly 15 to 12 feet behind the door is the most effective zero backpressure for the newer technologies, the newer front guards that are coming out from most quality PPB manufacturers.

This is some test data that AMCA provides to the manufacturers. It’s not reported on their website. So if you are interested in this kind of report from your manufacturer, you can always request that what they give is, unfortunately, it got cut off, but here on the bottom of the graph is airflow and the Y-axis shows static pressure, also known as back pressure, how the measurements are made for AMCA 240 there’s five measurements in positive backpressure, meaning that you have lower airflow and there are five matching measurements on negative backpressure, which is increasing your airflow.

You’re effectively pulling the air through the doorway. So, for this curve that is matched as a best-fit curve for all 10 points. Manufacturers report this single value has free air. The reason that that’s done is it’s very difficult to have the test chamber at exact backpressure. The reason behind this is we’re talking extremely low pressures.

As you can see over here, one PSI is equal to about 6,900 Pascal. Yeah, we’re at 25 Pascal she’s roughly 0.0036 PSI. It’s a special pressure transducer that was necessary to create this setup and allows AMCA to effectively and accurately measure 10 different air flows at very low-pressure changes.

Also in the test report, is this a table? You can see that the name, model number, the diameter, and some of these setup parameters, setback, distance, tilt, and a center line-height are reported. These are necessary to report on the AMCA website per their CRP program, which I’ll talk about later. Only certain variables are necessary so that it’s easily understood by the end-user.

We don’t expect everybody to dig through this table of data and try to understand what the airflow is. So, we the group at AMCA 240 are attempting to make this easily digestible and provide only one single number of free airflow.

Cool. So, the AMCA 240 is going through a review right now every five years. Then there’s a committee that reviews the standard and makes sure that it’s up to date. I’m part of that group this year. We’ve been discussing how to include battery PPVs into the standard and how to effectively measure those. One way about one way of doing that is by using a DC power supply, this gets away from any kind of AC power, as well as any kind of battery power.

The reason behind this is that battery power can be extremely good for a short period here in this curve. However, a majority of their power level will be on this portion of the curve, which is called the nominal voltage. So, what we’re trying to do is test these battery PPVs at their nominal voltage. To exclude any of these large curves in the front or the tail end of the battery’s life.

What we’re also doing is creating a supplementary runtime test. The reason behind that is you can imagine there’s a certain amount of power in a battery manufacturer can choose to dump all that power really quickly, or they can measure out that power as they see and extend the runtime. So, if we’re going to measure airflow performance, then we’d also have to measure runtime to make sure that the manufacturers are not.

So, to say, turning the dial on their equipment. We’re also looking at how to best report that in our test reports. I still haven’t come to any conclusions on that. Hopefully, in the near future, we can have some more traction and, and find a good solution. The other thing that the group is doing is looking at the different doorway sizes.

In the past, we had used an 80 inch, 80-inch-tall doorway, 36 inches wide, and in an effort to include international partners and manufacturers we’re changing that doorway so that it can be repeatable in other continents. That is, therefore allowing more people to be AMCA certified and have that access.

So, the AMCA 240, how does it benefit firefighters? First and foremost, and because certified PPVs are publicly available if you go to the AMCA cause website and you find the tab called certify. Certified product search and then positive pressure ventilator. You can find a list of manufacturers that are certified click on any of those manufacturers.

You can find a list of the ventilators that they’ve certified for. Can’t remember how to do that. Simply search positive pressure ventilator, and it’ll, it’ll pop up. This allows the end-user to double-check keep the manufacturer honest, make sure that the datasheet, the spec sheet that’s been distributed matches what’s publicly available on the AMCA website.

This creates a group of standardized results. You can see up here on the top, right? There’s a number of standardizing groups, a number of acronyms out there that do standardizing, and FPA, SME, NIOSH. Ventilators don’t really fall on any of those. So, we believe that it’s best for a third party to standardize the results and make those commercial or commercially available publicly available to the end-user, the firefighter.

Finally, they’ve been established for over a hundred years. They got their start in kind of the same way a group of HVAC companies got together, decided to make a standard. It’s all history from there, but they’ve been a long stent long-term partner. That’s trusted in the HVAC industry, and we hope to utilize their, their benefits.

This question was submitted during one of the registrations. How do you find the best PPE for you? It’s a good question. One, most firefighters are most interested in, so we’ll just kinda run through the logic there. So, what, what kind of space do you have? What, what compartment are you fitting a fan into?

That should be step one. How much space after that? You can start looking at different options. Do you need a gas, power fan? Could you fit two battery fans in the place of gas-powered fan? Maybe you like the water driven technology because there’s no emissions and you already have your hose laid out.

Whatever that may be. This would be a good time to decide on what is powering the fan next. Initially, you think maybe how much air do you or do I want? and I think I can safely say that the more air, the better, if you can. Get people back into their house. If you can get firefighters back to the station and cleaning their equipment faster.

That’s good. So, the more airflow, the better now having said that you want to compare apples to apples, you can’t compare an AMCA certified airflow. That’s been third-party tested and is publicly available to something like according to AMCA 240 or another version that is that has been out there in the industry because certified values are found on ample websites.

 certain manufacturers make those available in their catalogs as well. However, there’s also a, an uglier side that says according to AMCA 240 or something thereof, it’s basically saying not tested through. Well, it could be tested through, AMCA 240, but typically they’re not. You can imagine somebody saying, as you’re receiving, you’re doing the, the final checks on your truck.

The manufacturer says, oh, by the way, this is mostly an FPA compliant. In your mind. That’s not FPA compliant. So, this is something similar. A trick I use is, you know, how many zeros can you count on the end of an airflow is the more zeros you see, the less likely it is a lab accredited to test it in a technical setting.

So be sure to compare apples to apples when making measurement comparisons. Finally, kind of the, the extras features and accessories, you know, do you want to, want to mount it in with your truck. Once you found the right fan, then, then that should kind of aid in the decision process. Hopefully that helps you guys.

I’d like to end it with some good resources. UL’s firefighter safety and research Institute. Their team has been very good at pushing the, the way in, in providing open easy information for firefighters about certain situations you can see here on the right. They build a structure; they wire it up.

They, they put pressure transducers and they put thermistors. They measure everything that they can, and then they burn it down. Not always do you get that opportunity. This series of pictures to the right is from their effectiveness of fire service, positive pressure ventilation. You can see that it’s got a lot of wires going into it and they actually burn it down.

Their team’s been really good. They do a number of good things. They’re homing in on what a coordinated attack needs. That’s the balance between positive pressure, ventilation and positive pressure attack. Kind of hone it in that you really need water on the fire before you start ventilating, you need to have some kind of some path

actually, high rise buildings. I mistakenly put this under UL’s headline. However, the high-rise buildings and how to positively pressure stairwells came from the NIST study. So, my apologies there both websites, NIST, and UL have publicly available reports that you can read. They’re a little bit lengthy, so be ready for some reading, but they, they have a lot of good content if you want to dig into it.

Also, what UL’s team is doing is promoting the reduction of back pressure. It’s kind of commonly thought that the exhaust or the outlet of the flow path should be about two times larger than the inlet. UL did a study that measured the air flow. When the outlet is increased, they, they stopped at five times larger than the inlet and found an ever-increasing airflow.

So my takeaway is that if you need more air flow, increase the outlet, the exhaust of that flow path. It’s not always feasible in every situation, but if airflow is the critical path, then look at extending that exhaust opening. If you’re coming from Europe or across the pond Stefan Svensson. Sorry, Stefan, if I’m butchering your name, but he has a lot of good information out there written a number of books and papers.

He’s from Sweden. He’s a firefighter himself as well as a professor. He provides a lot of good information about ventilation tactics general rules of thumb. A really good resource over there, obviously I think is your regional fire instructors. They’re going to understand your situation, the best.

They’re going to take more into account than maybe your manufacturers and understand that not every department has all capabilities. So, I’d reach out to your regional fire instructor and of course, trusted manufacturers of PPVs, we make equipment the best we can for firefighters. We take a lot of input, a lot of questions from firefighters and, and hopefully we have answers. If we don’t, we should be looking to find those answers for you.

So, it kind of wraps up my presentation. That gives us a little bit more time than I had planned for questions and answers.

Perfect. So, thank you, Kyle. We’ll move on to Q&A. Before we get to that point, I do want to let people know that if you are looking for. PH credit for today, please.

Don’t forget to complete the survey at the end. Those credits will be issued within 30 days.

So, Kyle, what do you say that we let people see us so that they know we’re actually here live with them? What do I say? I don’t know. Say yes and turn on your camera. Oh, of course.

Right. Let me see if I can get mine working if it’s feeling alright. It’s feeling good today. We have just to remind everyone, if you do have questions to submit for Kyle, please go ahead and go to the questions box on your control panel and type that question in, and we will get to as many as we can.

There are two advanced questions, Kyle, that I want to bring up with you. One question is, could you please speak about the use of mixed flow direct drive fans for use in ventilation systems? Mixed flow fans are not Not the preferred type of fan that firefighters use. Seen that question. I looked them up real quick.

I wasn’t familiar with a mixed flow fan was, and to my understanding the benefits of a mixed flow fan come from a reduced sound. So, in an industrial setting like a hospital this makes a lot more sense or a restaurant, a school maybe however, on the fire ground sound, isn’t really the largest consideration.

What a firefighter is trying to do is get as much air flow through the building it’s already going to be extremely loud. So, the benefits of a mixed flow fan to my understanding wouldn’t necessarily make sense for a fireground doesn’t mean that you couldn’t test it on the AMCA 240 setup and have that report, although to my knowledge, mixed flow fans are not utilized by the firefighting industry.

Thank you for that. Another question that we received this person is asking, would this include this being PPV, assuming stair pressurization, fans and fans provided for smoke control systems? If they’re referring to permanent installations, then no. However, if you are talking about a temporary ventilation, if you’re talking about non-permanent setups, then yes.

So PPVs are commonly used to pressurized, stairwells and high rises or other apartment complexes. It’s. The goal to isolate smoke and a certain level or a certain room. So that the tactic is to pressurize the rooms around it and isolate the smoke and try to establish a flow path that allows the exit to, smoke, err, exit most closely to the seat of the fire as you can.

So yes, it is used on stairwells. If you ask for the test report, you may even find a more applicable airflow. If you have a charged stairwell and you place a PPV at, say a some somewhere along the high rise, you’ll have a higher you’re having less back pressure fight against the fan. So, if you asked for the test report from your manufacturer, you may be able to better figure out what your airflow affected airflow would be.

So, we have a question that’s come in. This person is saying that the testing setup that you showed has an incline for the PPV to sit on and blow towards an open door. The incline is not very likely to be there in most real-world scenarios. So does the PPV allow for rotating the discharge, according to the incline used for the testing standard and I, by the way, want to let you know Kyle, you can take control and go back on slides anytime you want.

Let’s see if I can get it to work here. All right looks good. So great question. First of all, great catch that’s less Western recognized and I think what they’re referring to is this platform that’s built on to the the actual floor.

What that’s meant is to represent the floor of a house or some kind of balcony, stoop, whatever it may be leading up to the doorway. So, doorways are flush with the ground for their setup. It was necessary to have the doorway off of the actual concrete floor of the lab. So, this is a runway, it’s actually flat.

It’s not inclined at all. It’s meant to represent the ground. The idea there is that you don’t want entrained air flow from below. You can imagine if this fan were propped up on a stand and there was a doorway across the room, and there was no ground simulated in between, you would get elevated airflow.

That would not be existed in reality. You want that ground to be there. So that entrained air flow is, isn’t pulled in from the bottom of that doorway. So, the intent is to keep the test as realistic as possible with the real-world situation that you would apply PPV to. Thank you for that.

Another question that we have is, are all battery fans tested on battery power? Currently,

I only speak for the, my company and if you’re interested, the test reports have many different photos, so we would be happy to provide the proof that AMCA gives to us as to how these fans are tested. It’s hard for me to say for anybody else. I don’t necessarily go to my competitors, asked for their test reports.

However, if you’re willing to reach out to your manufacturer and they, and they’re AMCA tested, then they’ll have photos at the bottom of that test report that will prove to whoever’s interested what the power source was.

Good point. Maybe we could start a new trend of asking competitors for their reports for full disclosure.

Yeah. All right. So, you have talked A good amount about entrained air in your presentation. So this next question is on that topic. This gentleman is asking how much of the doorway co how much of the doorway, the cone of air from the fan should take up? What is the additional air volume gained?

Perfect, great question. It hits home on why there’s new front guards attached to many of the latest PPVs. If the, if the idea is to seal the doorway, then you’re going to position forward and back until you reduce the smoke escaping from the top of the doorway, as best as you can. If the idea is to use these stream conditioners and really punch through the bottom half of the door.

Then what you’re trying to do is really get a feel for how much when does it your back, if you’re at a relatively stable state. So not a whole lot of wind, we would recommend 12, 15 feet. What that’s going to do is it’s going to increase the air through the doorway, approximately one and a half to two times, and that’s all-laboratory settings. So, this doesn’t include external factors that you might see on a fire ground. There’s a number of those that you can see shorts stoop in front of you a raging fire versus, you know, grandma cooking the soup a

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