Patent Application
20250073514
The present disclosure relates to extinguishing house fires using Carbon Dioxide and Dry Ice.
Shelby Hall wrote in “Fire Loss in the United States”, “In 2022, local fire departments responded to an estimated 1.5 million fires in the United States. These fires caused 3,790 civilian fire deaths and 13,250 reported civilian fire injuries. The property damage caused by these fires was estimated at $18 billion. On average, a fire department responded to a fire somewhere in the US every 21 seconds in 2022. A home structure fire was reported every 88 seconds, a home fire death occurred every three hours and fourteen minutes, and a home fire injury occurred every 53 minutes.”
U.S. Fire Administration reported that as of September 2024, 40 Firefighters and 1,403 civilians died because of fires.
Currently, spraying water on building fires by firefighters is the normal way of fighting house/building fires. By watching on Youtube at the videos of firefighters spraying water on house fires, it does not seem very effective. It is not easy as fires may be burning in an area unreachable directly by the water. Firefighters could be seen to direct the water into the windows or the roof. The fires kept burning because the water stream was unable to reach the fire behind the wall or inside the ceiling under the roof. Fires continued to burn for quite some time. Any valuable things in the house would also be damaged by water. Thus, it is apparent that we need a new and effective house fire firefighting technique.
Once firefighters arrive at a house fire, packages of Dry Ice powder/small pellets/flakes should be thrown into the house from any available doors and windows. The packages or buckets of Dry Ice should be packed in a way to allow the Dry Ice to spread out as much as possible after being thrown. Dry Ice should be placed on a plastic sheet and the edges should be picked up or collected and hold tight together without tying up with strings. When this pack of Dry Ice is thrown into the window or door, it will release all the Dry Ice which will spread out onto the floor. The more it spreads, the more quickly it sublimates. If the fire is burning upstairs, Dry Ice can even be thrown into the doors or windows downstairs because the Carbon Dioxide from it can be sucked up to the fires.
Drones carrying powder of Dry Ice should be flown into the house to dump packages of pellets of Dry Ice or spray or spread the powder of Dry Ice in as many rooms as possible. After emptying the powder of Dry Ice, the drones can come out to refill and repeat the process again.
Powder of Dry Ice can also be spread outside of the building especially, over the windward side of the fire if fire is burning outside of the building. With other large fires, dry ice has to be spread on the fire and on all sides of the fire to cut off the Oxygen from the surrounding area. The air around the fire is 78% Nitrogen, 21% Oxygen, 0.9% Argon and 0.04% Carbon Dioxide. With plenty of Oxygen, the fire will burn brighter and as the Carbon Dioxide produced by the burning is hot, it rises and creates low pressure at the base of the fire which sucks in more Oxygen to burn.
Oxygen content needs to be more than 15% in the air for diffusion flame production and when the Carbon Dioxide from the dry ice expands and rushes into the fire, it stops burning as there is more Carbon Dioxide around the fire. Kate S. Zalzal wrote for the Earth Magazine saying, “They have found that fires, even if ignited, will not propagate if the atmospheric oxygen concentration is below 16 percent. At our modern oxygen level of 20.9 percent, fires ignite and propagate readily.”
When cold Carbon Dioxide from dry ice overwhelms the inside of the house and the surrounding area, Oxygen cannot get near the fire and the fire will die down.
Powder of Dry Ice will be sprayed or spread out over the fire or close to the fire. The powder or flake of dry ice is small enough to sublimate quickly after hitting the floor. The drone that sprays Dry Ice can be flown closer to the fire and can spray Dry Ice directly into the fire for it to quickly sublimate because of the heat.
Dry Ice is frozen Carbon Dioxide. It sublimates (evaporates directly into gas) at −78.5 degrees Celsius or −109.2 degrees Fahrenheit. Before the carbon dioxide gas gets to the Standard Temperature (0 degree Celsius), it absorbs the heat from the scene of the fire and as it gets hotter, it expands. This cools the temperature of the scene of the fire.
Carbon Dioxide molecule has one Carbon atom (atomic weight 12) and two Oxygen atoms (each has atomic weight 16). As Carbon Dioxide has a molecular weight of 44 (12+16+16), there is 44 gm in one mole. One mole of gas at Standard Temperature and Pressure (0 degree Celcius and 1 ATM) is 22.4 Liters. So one pound (454 gm) of dry ice will produce about 231 liters (61 gallons) of Carbon Dioxide gas at STP. The temperature at the fire scene can be hundreds of degrees. Let's assume it is about 200 degrees Celsius (It could be up to more than 1000 degrees Celsius). According to Boyle's and Charles' law P1 V1/T1=P2 V2/T2, The volume of Carbon Dioxide from the one pound of the dry ice without considering the air pressure would be more than 400 liters or more than 105 gallons. If 10 lbs of dry ice are dropped in the house, the volume of Carbon Dioxide would be more than 1,000 gallons. When this Carbon Dioxide pushes into the fires, Oxygen does not have a chance to get in and combine with the fuel. House fire will be extinguished.
University of Massachusetts Amherst says in its Environmental Health & Safety page under the heading “What are the hazards”, “Cryogens and dry ice can expand 700 to 900 times their volume upon boiling/sublimation.” Department of Biology at the University of York says on its website that 10 kg of dry ice sublimes into about 5.4 cubic meters of carbon dioxide gas. (That means 22 lbs of Dry Ice sublimes into 1426 gallons and if this expands 800 times, it would be about 1,140,000 gallons.) And the expansion ratio of dry ice is 845. That means 1 lb of dry ice would sublime into 6.5 gallons of carbon dioxide. So if this gas is heated from −78 degrees Celsius to 200 degrees, the volume would be more than 158 gallons. 100 lbs of dry ice would produce more than 15,800 gallons of Carbon Dioxide gas occupying the whole house. However, it should be noted that not all the Dry Ice would sublimate immediately into gas once it gets in the burning house.
Fire engine trucks hold from about 300 to 1,250 gallons of water with an average of 500 gallons. Water sprayed on fires does not expand like Dry Ice and extinguish fires only on contact even though the steam coming out of the fire does suppress the fire. Most of the water just flows down the floors and to the ground. Properties in the house are also damaged by the water. However, Carbon Dioxide is gas and will not damage properties in the house.
A fire that is burning has only three elements: Fuel (wood or furniture), flames and Oxygen from the air. Fuel and Oxygen combine with the help of the heat from the flames and produce hot Carbon Dioxide and other toxic fumes and soot which rise up into the sky because hot air is lighter. Oxygen from the cold surrounding air rushes in towards the flames because the pressure at the base of the fire is low and so the burning goes on. When the Carbon Dioxide from the dry ice expands and comes up from the floors, it pushes out the Oxygen from the surrounding air that is rushing in to the flames. The flames cannot get enough Oxygen to continue burning and the fire is snuffed out. This Carbon Dioxide from Dry Ice, unlike the hot Carbon Dioxide that comes out of the burning flames, is quite cold and so it does not rise up but rushes in to the fires because the low pressure surrounding the burning flames suck in the cold Carbon Dioxide instead of Oxygen. In turn, the fire stops burning because it cannot get enough of the Oxygen it needs.
The volume of Carbon Dioxide from the dry ice is several times greater than the water or fire retardants and also it can extinguish fires that the dry ice does not touch because the cold Carbon Dioxide can rush towards adjacent fires or fires behind the wall or in another room. So using dry ice to extinguish fires is much better.
The cost of dry ice is about $1.00 per lb. Carbon Dioxide to produce Dry Ice is reclaimed from industries and so it is not only cheap but also does not harm the environment. In addition to Dry Ice, Carbon Dioxide gas from cylinders can also be used to fight house fires.
Firefighters can carry a 10 lb, 20 lb or 50 lb Carbon Dioxide cylinders on their backs or by hand and can spray the gas into any opening of the house or building or a Condo apartment. Drones carrying Carbon Dioxide cylinders can be sent out to spray the gas into the windows or doors or into the house or room where the fire is burning. They don't have to even enter the building. If the fire is too big, each fire fighter could even use two cylinders at the same time to spray Carbon Dioxide gas into an opening. The gas will expand and reduce the ratio of available Oxygen to below 16% so that fire can stop burning. Carbon Dioxide just needs to dilute Oxygen to below 16% to snuff out the fire. Fire fighters should be careful because Carbon Dioxide spray coming out of the cylinders can be very cold and could hurt eyes and skins.
It should be noted that Carbon Dioxide is heavier than air and will flow to lower levels and if there are people in the house, people inside the room or basement or lower floors will not be able to get enough Oxygen to breathe. After the fire is extinguished, big fans or leaf blowers can be turned on to push the Carbon Dioxide out until it is safe for people to enter the house of the building or the apartment.
Fire trucks can also carry bigger Carbon Dioxide cylinders and plastic pipes and (garden hoses) reels. Instead of unrolling water truck hose and joining them, just unrolling the long plastic pipe will save time. Firefighters can then aim the Carbon Dioxide gas into the doors or windows or openings of the house or building to extinguish the fire. The spraying end of the hose can even be carried by drones to higher rooms.
Not every local Fire and EMS station in a city needs to store Dry Ice or Carbon Dioxide cylinders. Only a few of the stations need to store them and bring to the house fire when necessary.
There are important things to note when using Dry Ice and Carbon Dioxide as firefighting agent. Firefighters handling Dry Ice should be trained in the handling and dangers of it. It cannot be in totally closed box. It must not be handled with bare hands. It cannot be transported in a car with windows closed. People handling Dry Ice need to wear Safety glasses. If there are people in the building, firefighters should consider whether it is prudent to use Dry Ice. Both the fire with toxic fumes and the Carbon Dioxide from the Dry Ice can kill a living person. Firefighters going into the house after the fire dies down must be careful. Carbon Dioxide from the fire and from the Dry Ice or the Carbon Dioxide cylinder will linger in the house and any person or animal may die from lack of Oxygen. So as soon as it is safe to go into the house, it should be immediately checked to see whether someone is inside. If so, they should be immediately treated and bring out to fresh air.
A website “co2meter dot com” says, “CO2 cylinder pressure is about 860 psi at normal room temperature. Typical CO2 cylinders store about 20 lbs or 50 lbs. of liquid CO2. Two pounds of liquid CO2 expands to about 20 cubic feet of gaseous CO2 at atmospheric pressure, or expands at a rate of 535:1. This means that in an enclosed room the CO2 gas can quickly fill with CO2 and either poison an individual or displace all the oxygen available for breathing. Because CO2 is heavier than air it will also fill any low areas like basements or under floor service areas first. If there is little air movement, pools of CO2 can exist for many hours. Liquid CO2 temperature is also important. If the gas escapes quickly, it is discharged at sub zero temperatures and produces a mixture of CO2 gas and “snow”. This “CO2 snow” is momentarily the same temperature as dry ice (about −110 F. or −79 C.) and can quickly result in frostbite or frozen skin.” However, most of the Carbon Dioxide would be suck up by the low pressure of the fire.
When fighting metal fires, one should be careful about the use of Dry Ice. “Note that certain metals react exothermically with nitrogen or carbon dioxide, so the only acceptable inert gases for these metals are helium and argon. Halons should not be used on metal fires.” (PDHonline Course M282: Fire Dynamics Series: Fire Protection Fundamentals. Instructor: Lawrence J. Marchetti. p-31).
One should also know that according to Hazmat University, Dry Ice is regulated in transportation and shipping is limited to 200 Kg (441 lbs). Whoever handling Carbon Dioxide cylinders should also be familiar with 46 CFR § 147.65—Carbon dioxide and Halon fire extinguishing systems.
