These functional requirements were selected by discussing the properties of existing equipment in addition to speaking with stakeholders about their needs for a potential new piece of equipment. The source of each need is listed in the table below. Each group member was tasked with generating 1 functional requirement to start. After 12 individual functional requirements were proposed, we discussed as a group and generated the additional 9 functional requirements.
Functional Requirement 1: A module should be able to be swapped in XX seconds
The decision for this requirement will be made in the spring semester. This was pushed back to next semester as depending on the device created this time will change. If an eyepiece is made it will take a different time than a body device, so further project information was deemed needed before the finalization of this constraint.
Functional Requirement 2: The system, as sold to fire departments, must cost less than $1000 in total.
The system must not cost more than $3000 to develop as that is the budget given to our team, but this can be negotiated if we find we need more money. The final product should not cost fire departments more than $1000 per device as that is the approximate cost that devices on the market which serve similar purposes are, such as a thermal imager [1].
[1] IFW Staff. “Technologies That Will Transform Industrial Fire Fighting in 2022.” Industrial Fire World, Industrial Fire World, 28 Dec. 2021, https://www.industrialfireworld.com/626600/technologies-that-will-transform-industrial-fire-fighting-in-2022.
Functional Requirement 3: GPS should be able to track the system to within XX meters
The decision for this requirement will be made in the spring semester. This is due to the fact that currently the device may not need a GPS tracker, and this may be an extended feature that will be explored later.
Functional Requirement 4: The system must weigh less than 5 pounds if worn on the body or 3 pounds in worn on the head
Weight of equipment is arguably one of the most important characteristics a piece of gear can have. Firefighters often must carry 60+ pounds of gear into the hazardous situations they are forced to confront. NYC firefighters must pass a test while wearing 50 or more (22.68-kg) pounds of gear and while moving heavy pieces of equipment such as ladders and hoses, while only given a 20 second break in between during the 30 minute exam [1]. The helmet of a firefighter and the mask weighs as much as 6-8 pounds (2.7-3.6 kg) depending on the quality of the gear. Meaning the device we create must be capable of being put on the gear without over exerting the firefighter. So the weight should either be 5 or under pounds if the device is to be put on the body. But if the device is to be supported by the neck the maximum weight should be 3 (1.5 kg) pounds or less. These weights come from when the device is added on top of the gear it should be barely felt and should not impede the user, and adding 10% or less than the additional weight is deemed within that range. Any heavier load may hinder performance in the field adding more risk to the user rather than lowering it, thus countering the whole point of the device.
[1] “Welcome to Nyc.gov | City of New York.” NYC Gov, NYC, 1999, https://www1.nyc.gov/assets/fdny/downloads/pdf/join/join-cpat-orientation_guide.pdf.
Functional Requirement 5: Training with the device should take less than 12 hours
One of the functional requirements I am responsible for is that our design should be simple. It is crucial for our design to be simple to use because in the moment of fire the firefighter should be able to use our product and quickly receive the desired outputs of the product. Compared to other equipment that firefighters use they have to undergo courses that last about 7 weeks for 6 days a week that cover PFT training, strength, grip strength, Bunker Gear/SCBA work capacity efforts, and long mini-events. Our product should take much less time for training as it should only take 10 hours of training. This design will be simple enough that most of the training will be put towards training experience with the product and communication practice and haptic feedback training as well.
[1] “Smoke Diver Training Plan.” Mountain Tactical Institute, Smoke Dicer Training, 12 Dec. 2020, https://mtntactical.com/shop/smoke-diver-training-plan/.
Functional Requirement 6: The system should be able to be setup in under 1 minute
Whenever there is a situation in which firefighters are needed to respond, every second counts from the moment they are called to the moment they enter a building. A firefighter that operates in a New Jersey residential area provided information in good detail about the set up time and procedure when they arrive at a situation. He described that their staff needs to go directly into a building once arriving on site in order to prevent civilian casualties. This means that the firefighters need to be set up beforehand and be ready to go when they arrive on site. The few exceptions to this rule are the mechanical devices that they’ll use on site, because the firefighters won’t know what they’ll need to use until they arrive. This means that these devices need to be easy and quick to set up so that they do not delay the firefighters from performing their job. Additional information was found online but wasn’t considered because it did not provide numerical values for how long mechanical systems should take when being set up [1]. However the online information did qualitatively agree with the information provided by our stakeholder from New Jersey that everything on site should be set up as quickly as possible. We believe it would be appropriate for our device to be set up in under 1 minute.
[1] “Fire Response Time.” Fire Response Time, https://fems.dc.gov/page/fire-response-time. Accessed Dec 6th, 2022.
Functional Requirement 7: The system uses no gas or hydraulic sources of power or actuation
Our system will be powered by batteries that will be interchangeable so that it is easy to replace batteries while also being easy to charge. Our system may contain subcomponents of sensors, gas sensors, screens, cameras, and maybe even vibrating components that will run off of the battery, as these subsystems run off of electricity. Our group will not work with any gas-powered system as this product will likely be on the firefighter’s body while fighting off a burning building and gas is highly flammable with the use of a hydraulic system as the oil used for the hydraulics system is also highly flammable. The battery run time will be easily changeable as our group will determine that only a set voltage is needed but we can source a battery with a higher amp hour value. The battery in this system will be insulated well so it is not affected by the high temperatures from its surroundings.
Functional Requirement 8: Must be impact rated to IK11
IK rating is an international standard to measure a product’s resistance to impact. When looking at impact ratings the first thing to consider is weight. IK impact ratings are based on impact energy in Joules. First, the weight limit was determined to be 8 lbs (3.63 kg) around the torso and 4 lbs (1.81 kg) for anything on the head. To come up with appropriate measurements, drop height will be determined based on a 7 foot person. This would allow it to be inclusive of almost all users and leave leeway for most. Since the torso height is assumed to be about half of a person’s total height and the weight around the torso is double that of the weight on the head, the IK impact rating will be the same for both. Additionally, it will be assumed that the product will start with an initial downward velocity of zero and all force will be transferred into the impact with no rebound. Setting acceleration due to gravity equal to 9.81 m/s^2 we can determine that the impact energy for a drop would be about 38.1 J. Looking at the table from the website we can see that the closest thing when rounding up is 50 J impact which corresponds to a IK11 impact rating. This would allow for an over 9 foot drop for the head parts and over 4.5 foot drop for the torso part, leaving plenty of room for higher drops or tumbles.
[1] Design plan Lighting. “IK Rating for Impact Resistance.” Designplan Lighting, 28 July 2022, www.designplan.co.uk/technical/technical-information/ik-rating-2.
Functional Requirement 9: Must not be damaged by XX ppm particles in the air (e.g., dust)
The decision for this requirement will be made in the spring semester.
Functional Requirement 10: Must function properly while in contact with water up to IP66K standards
The Ingress Protection (IP) rating system is used to describe a device’s resistance to intrusion by solids and liquids. It consists of two numbers, the first–which goes from 0 to 6–denotes the resistance to solid particulate intrusions such as dust or sand. The highest rating, 6, means that there cannot be any ingress of dust. This is important in a fire because of the harsh environment equipment is subjected to. The second number in the IP rating ranges from 0 to 9 [1]. IPX6K means that the device is protected from pressurized water on all sides. This is a requirement for devices used in a fire because there is a high possibility of being hit with water from a firehose. It is important that this does not ruin the device.
[1] Bloch, Heinz P. “Ingress Protection Code Explained.” World Pumps, vol. 2009, no. 11, Mark Allen Group, Nov. 2009, p. 26. https://doi.org/10.1016/s0262-1762(09)70418-3.
Functional Requirement 11: Smaller than 46 x 36 x 30.5 cm (L x W x H) for headgear and 35.5 x 56 cm x 94 cm for bodywear
A firefighter close to the team was contacted and asked to measure the different dimensions of both their fire coat and their helmet that they wear on calls. Both the coat and the helmet were designed for a large person which means that the dimensions (L x W x H) should be the absolute maximum that the device takes up. These values are generated with the idea that if the device is to be worn on the face, it should be able to fit within the helmet itself and have dimensions of no more than 46 x 36 x 30.5 cm. The device could possibly have a small portion of it outside of the helmet. If the device is meant to be worn under a firefighter’s coat, it will obviously need to be a different size and shape, and have dimensions of no more than 35.5 x 56 cm x 94 cm. Therefore, separate functional requirement values are needed to describe the size constraint of the device. If the device is to be worn under the firefighter’s coat, the maximum dimensions should be generated from the length, width and height of the large fire coat. For this information, several sources gave dimensions similar to the dimensions of pants and shirts based on the size of the person, e.g. 34-32 or “medium.” Since this functional requirement is based around the idea of storage and transportation, these values need to also be based around the way the device would be stored. This information was difficult to find online, so reaching out to a stakeholder was the best option for gathering it.
Functional Requirement 12: Calibration should not take more than XX minutes
The decision for this requirement will be made in the spring semester, as we’re not entirely sure what type of sensors we’re going to be using or what their specifications and readings will be.
Functional Requirement 13: Maintenance should not take more than 20 minutes a day
Firefighting PPE needs to be regularly checked on to ensure the safety of the user and the longevity of the equipment. Things like turnout gear and helmets should be washed after every exposure to smoke or fire [1]. While a helmet may be quick to wash and dry, turnout gear is supposed to be washed and air dried, which can take 1-2 days [2]. This may discourage firefighters from taking proper care of their gear and put them at risk of further exposure to toxins. Electronic equipment, such as gas detectors, requires frequent testing to confirm that it is working properly. Bump tests, which may only take a few minutes, are conducted on gas detectors to see if they respond to hazardous gasses [3]. These detectors, as well as other electronics, also require decontamination [4]. This is done by simply brushing or wiping down the equipment [5]. Assuming that our solution will likely be more similar in nature to the electronic devices, 20 minutes seems like a reasonable amount of time to inspect and clean the device. A maintenance time equal to or less than 20 minutes after every exposure should be quick enough to not discourage firefighters from taking proper care of the equipment.
[1] Bullard. “Cleaning Your Fire Helmet.” Bullard, Bullard, 31 Oct. 2022, https://www.bullard.com/insights/cleaning-your-fire-helmet/. Accessed 6 Dec. 2022.
[2] Avsec, Robert. “Is Drying Time Keeping You from Cleaning Your Turnout Gear as Often as You Should?” FireRescue1, 17 Sept. 2021, https://www.firerescue1.com/fire-products/turnoutgear/articles/is-drying-time-keeping-you-from-cleaning-your-turnout-gear-as-often-as-you-should-lC4ShxBbeXdT2gob/. Accessed 6 Dec. 2022.
[3] ITM Instruments Inc, director. How to: Bump Test a BW Gas Detector. YouTube, YouTube, 7 Dec. 2017, https://www.youtube.com/watch?v=GcUGjiTKNMQ&ab_channel=ITMInstrumentsInc. Accessed 6 Dec. 2022.
[4] “Deconning a Radio.” 27 Sept. 2016, https://forums.firehouse.com/forum/firefighting/firefighters-forum/2067095-deconning-a-radio. Accessed 6 Dec. 2022.
[5] “Six Tips to Maintain Your Two Way Radio.” TwoWay Radio Gear, https://twowayradiogear.com/blogs/news/six-tips-to-maintain-your-two-way-radio#:~:text=Keep%20your%20device%20away%20from,dirt%20do%20not%20infiltrate%20them. Accessed 6 Dec. 2022.
Functional Requirement 14: Data should be accurate within XX% of the true reading
The decision for this requirement will be made in the spring semester, as we’re not entirely sure what type of sensors we’re going to be using or what their specifications and readings will be.
Functional Requirement 15: Video quality should be XX resolution
The decision for this requirement will be made in the spring semester, mainly because we’re not entirely sure if our device will have some form of video yet.
Functional Requirement 16: System should store at least 256 gigabytes and have at least 4 gigabytes of processing memory
The minimum requirement for random access memory (RAM) to run a standard 64-bit operating system is 2 GB [1], and it’s unlikely that our system exceeding that of a fully realized user interface; RAM sticks typically come in 4 GB sections, so one DIMM would likely be enough for the purposes of our computerized system. This requires the system to be of a certain size (Standard DIMM – 133.35mm x 30mm x 5.1mm; mini-DIMM – 82mm x 30mm x 3.8mm) in order to fit the memory stick [2]. Should the system require more than the expected amount of memory, the sticks are thin and can be easily stacked on top of one another without needing much expansion in the way of physical size. Should the system need to store data, standard micro-SD cards typically range between 128 and 256 GB (some even go up to 1 TB), while only being 15mm x 11mm x 1mm in size [3].
Depending on the sensors we use, we will need to record data to be stored for a set amount of time (i.e. record for 30 minutes while in a fire), which will translate to a set amount of GB based on what the sensors will measure. These values may be updated accordingly when we have a better idea of the size of our sensor data.
[1] “How Much Ram Does Your Windows 10 Pc Need?” ZDNET, accessed Dec. 6 2022, https://www.zdnet.com/article/how-much-ram-does-your-windows-10-pc-need/.
[2] “Introduce of DDR4/DDR3/DDR2/DDR1 Memory Module Form Factors.” CST Inc,DDR4,DDR3,DDR2,DDR,Nand,Nor,Flash,MCP,LPDDR,LPDDR2,LPDDR3,LPDDR4,LRDIMM, Memory Tester Automatic DIMM SODIMM Handler Company Provides Memory Solution, accessed Dec. 6 2022, https://www.simmtester.com/News/PublicationArticle/168.
[3] “SD Card Types, Form Factors & Specs.” CDW, accessed Dec. 6 2022, https://www.cdw.com/content/cdw/en/articles/hardware/types-of-sd-cards.html#:~:text=The%20dimensions%20of%20a%20Micro,and%20other%20devices%20more%20easily.
Functional Requirement 17: Must be able to run for 60 Minutes
The average house fire takes anywhere from approximately 5 minutes to 2 hours to put out from the time the fire first starts [1]. So, excluding the time it takes for a person to notice the fire and contact 911 (~3-5 minutes), time for dispatch to contact the local fire station (~1-2 minutes), and time waiting for firefighters to arrive (~5-10 minutes), it takes an average of 38 minutes (usually ranges from 20-40 minutes) to put out a house fire once the firefighters arrive [1]. This amount of time varies based on factors such as construction, fire department response time, the number of emergency resources, cause of the fire, water supply and how far advanced the fire is when it is called in. An entire house can be ignited in as little as 5 minutes to up to multiple hours. Fires typically spread quicker in smaller houses with more synthetic construction materials that are more commonly found in modern homes than in the past. A fire can double in size in a time range as small as every 15 seconds, while on the slower end it can double in size about every 2 minutes depending on these various factors. After conducting research independently as well as talking to various firefighters and stakeholders, we found firefighters are very commonly limited to 15 minutes of air supply inside a burning building at one time. Thus, firefighters are trained to give themselves 7 minutes to enter the building and 7 to exit [2]. So, because the average house fire takes 38 minutes to extinguish and each firefighter is limited to 15 minutes inside a burning house at once, the device we create should be able to run for at least an hour at once. This ensures that the device’s power supply will last 4 times as long as the required time for one trip in and out of a burning building, and it will provide sufficient power in the event that the fire lasts longer than the average 38 minutes and give the firefighter a time cushion in the event this occurs.
[1] “How Long Does It Take to Put out a House Fire?” A Website about Firefighters and What They Do, https://firefighterinsider.com/how-long-put-out-house-fire/.
[2] “Firefighter Search and Rescue Manual & Tips 2021.” Fire Training Toolbox, 21 Oct. 2018, https://www.firetrainingtoolbox.com/firefighter-search-rescue/.
Functional Requirement 18: Should last for XX uses for YY cost
The decision for this requirement will be made in the spring semester. This is mainly because we’re not entirely sure what device we’re going to design yet, so we have no frame of reference on what to compare the design to.
Functional Requirement 19: Must operate at 160 ℃/ 433.15 K for at least 15 minutes
Standard house fires can reach temperatures of 1100 °C in as soon as 3.5 minutes [1] [2]. While this may be a baseline for initial temperatures of house fires, we do not expect the product or its power supply to be directly exposed to these conditions. A study performed by Michelle K. Donnelly, William F. Young, and Dennis Camell describe the behavior and operation of handheld portable radios at set temperatures and times [3]. The conditions for the first tests were 100 ℃ for 25 minutes, 160 ℃ for 15 minutes, and 260 ℃ for 5 minutes. At Thermal Class 1, the portable radios were able to maintain a stable frequency. At Thermal Class 2, all radios experienced some kind of issue. Four radios were not able to transmit at all during the exposure to these conditions, while the other 3 radios experienced signal drift. Lastly for Thermal Class 3, all radios with exposed components did not survive the fire or cool-down period essentially limiting effective operational temperatures to Thermal Class 2. These radios listed the operational temperature to be 60 ℃ [4]. The time it takes for an average house fire to be suppressed can take anywhere between 5 minutes to 2 hours. This can all be dependent on the size of the area, the response time, available resources, cause of the fire, and how far it has spread [5]. Knowing that the time it takes for fires to be put out can vary greatly, we should consider developing a containment unit to protect the radio or product from extreme heat, developing a new product with higher heat resistance altogether, or figuring out how to limit the signal drift caused by intense heat. Based on this research, the device should operate at 160℃ for approximately 15 minutes.
[1] San Francisco Fire Department. “Home Fire Facts.” SF Fire, https://sf-fire.org/home-fire-facts. Accessed 6 Dec. 2022.
[2] “What Is the Temperature of Fire?” Target Fire Protection, 17 Jan. 2020, https://www.target-fire.co.uk/resource-centre/what-is-the-temperature-of-fire/#:~:text=Orange%20flames%20range%20from%20around,C%20to%203000%C2%B0C. Accessed 6 Dec. 2022.
[3] Donnelly, Michelle K., William F. Young, and Dennis Camell. “Performance of Portable Radios Exposed to Elevated Temperatures.” (2014). Accessed 6 Dec. 2022.
[4] “Firefighter Radios May Fail During High-Temp Fires.” NIST, 27 Nov. 2017, https://www.nist.gov/news-events/news/2006/09/firefighter-radios-may-fail-during-high-temp-fires. Accessed 6 Dec. 2022.
[5] “How Long Does It Take To Put Out a House Fire?” Firefighter Insider, https://firefighterinsider.com/how-long-put-out-house-fire/. Accessed 6 Dec. 2022.
Functional Requirement 20: Audio must be audible at XX decibels to audience and audio must be received at YY decibels
The decision for this requirement will be made in the spring semester because it is not yet known what type of audio the system will be producing and whether it will only need to be heard by the firefighter using the device or by other firefighters in the area as well.
Functional Requirement 21: Must fix problems in the field within 10 minutes or fewer
During a fire every second counts, so the quicker you can identify a problem and fix it the better. The problem should be able to be identified and dealt with all while en route to emergency. The standard time to travel to a fire is 8 minutes so the system should be able to be fixed in a comparable amount of time, 10 minutes [1].
[1] “Fire Response Time.” Fire Response Time, https://fems.dc.gov/page/fire-response-time#:~:text=and%20incident%20command.-,NFPA%20Standard%201710%20establishes%20an%2080%20second%20%E2%80%9Cturnout%20time%E2%80%9D%20and,than%2090%25%20of%20dispatched%20incidents.