説明
Wet chemical extinguishing agents, such as potassium acetate and potassium citrate, when sprayed on a grease fire, extinguish the fire by smothering and cooling. The wet chemical agent reacts with the hot grease and forms a layer of soap-like foam on the surface of the fat, which acts as an insulation between the hot grease and the atmosphere, preventing the escape of combustible vapors and oxygen supply.The wet chemical agent also absorbs heat from the grease and lowers its temperature below the ignition point12 References:
What is the Difference Between a Wet and Dry Chemical Fire …
Wet Chemical (Class K) Fire Extinguisher – Portable – WFX

説明
The safety class for propane refrigerant R-290 is A3, which means it has no toxicity but high flammability.
The safety class is determined by the ASHRAE Standard 34, which assigns a capital letter (A or B) for the toxicity level and a number (1, 2, or 3) for the flammability level of a refrigerant. Propane has a very low global warming potential and ozone depletion potential, but it also has a very low flash point and high auto ignition temperature, which make it highly flammable in the presence of ignition sources.References:Propane R-290 | Copeland US;R-290 Propane Refrigerant Fact & Info Sheet;Safety Data Sheet – Refrigerants; NFPA Fire Protection Handbook, 21st Edition, Chapter 3, Section 3.3.4.

説明
The data of a pre-incident plan should be evaluated after an incident, as part of the post incident critique or analysis. This is to assess the accuracy, completeness, and usefulness of the pre-incident plan, and to identify any changes or updates needed based on the lessons learned from the incident.Evaluating the pre-incident plan after an incident can also help improve the emergency response performance and the fire safety management of the site.References:123

説明
valve at the inspector’s test connection.
For wet-pipe automatic sprinkler systems, the only proper way to test the operation of a vane-type water flow alarm initiating device is to open the valve at the inspector’s test connection. This is a small valve that is located at the end of a pipe that is connected to the sprinkler system, usually at the most remote or highest point. The inspector’s test connection simulates the flow of a single sprinkler head and activates the vane-type water flow switch, which in turn triggers the fire alarm panel and the external alarm devices.Opening the valve at the inspector’s test connection also allows the water to drain from the system, preventing corrosion and freezing1234 Opening the main (2 in. diameter) drain is not a proper way to test the operation of a vane-type water flow alarm initiating device, because it does not create enough flow to activate the switch. The main drain is used to drain the entire sprinkler system for maintenance or repair purposes, and it is usually located at the main riser or the fire department connection.Opening the main drain may also cause a pressure drop in the system, which could affect the performance of the sprinklers1234 Opening the alarm test by-pass valve at the system’s main riser is not a proper way to test the operation of a vane-type water flow alarm initiating device, because it does not simulate the actual flow of a sprinkler head.
The alarm test by-pass valve is used to test the operation of the external alarm devices, such as the water motor gong or the electric bell, without activating the fire alarm panel. The alarm test by-pass valve is usually located near the alarm check valve or the water flow switch, and it allows water to flow through a small orifice to the alarm devices.Opening the alarm test by-pass valve does not create enough flow to activate the vane-type water flow switch1234 Opening the check valve from the city connection is not a proper way to test the operation of a vane-type water flow alarm initiating device, because it does not create any flow in the sprinkler system. The check valve from the city connection is used to prevent the backflow of water from the sprinkler system to the city water supply, and it is usually located at the fire department connection or the main riser.Opening the check valve from the city connection does not affect the water flow in the sprinkler system, and it does not activate the vane-type water flow switch1234 References:
Fire Sprinkler Flow Switch & Tamper Switch Inspection & Maintenance3
Sprinkler System Water Flow Device Testing – ORR Protection2
VSR-AT Auto-Test Waterflow Alarm Switch | Potter Electric4
WFDNA Series Vane-type Waterflow Detectors – Steel Fire Equipment5

説明
According to the web search results, 79% of fire departments surveyed participate in the delivery of emergency medical services (EMS).This is based on the NFPA report “US Fire Department Profile 2020″1, which states that nationwide, 37% of fire departments provided no EMS, 46% provided basic life support (BLS), and 17% provided advanced life support (ALS). Therefore, the percentage of fire departments that provided either BLS or ALS is 46% + 17% = 63%. However, this does not include fire departments that provided EMS through a third-party contract or agreement.According to the NFPA fireservice survey from
2018-20202, 16% of fire departments reported having such an arrangement. Therefore, the percentage of fire departments that participated in the delivery of EMS in some form is 63% + 16% = 79%.References:
NFPA report – U.S.fire department profile3
US Fire Department Profile 2020 Supporting Tables2

説明
The weight of items such as furnishings, people, and equipment is called dead load. Dead load is the permanent load that is applied to a structure or a component of a structure1. It includes the weight of the structure itself, as well as any fixed attachments or equipment2. Dead load is one of the factors that determines the fire resistance rating of a structure or a component3. References:
NFPA 557: Standard for Determination of Fire Loads for Use in Structural Fire Protection Design An Overview of Fire Protection for Structural Engineers SFPE Handbook of Fire Protection Engineering, 5th edition

説明

煙探知機
エクスペリエンス
The smoke detector type that contains a small amount of radioactive material and functions by sensing a decrease in conductance of the air when smoke particles enter the chamber is theionization smoke detector.
Ionization smoke detectors use a small amount of americium-241, a radioactive element, to ionize the air molecules inside a sensing chamber. This creates a low-level electric current between two electrodes. When smoke enters the chamber, it disrupts the ionized air and reduces the current flow. This triggers the alarm to sound.Ionization smoke detectors are more sensitive to small particles of smoke, such as those produced by flaming fires1.However, they may also be more prone to false alarms from cooking or steam, and they require proper disposal of the radioactive source2.
参考文献
Smoke Detector Types: Which Type of Smoke Detector Is Best? – X-Sense
How Does Your Smoke Detector Work? – ThoughtCo

説明
ANSI S1.4a
Sound meters used to test notification appliances in fire alarm systems shall comply with the standard ANSI S1.4a, Specifications for Sound Level Meters, Type 2 requirements, according to NFPA 72 2010, the National Fire Alarm and Signaling Code.This standard specifies the performance and accuracy criteria for sound level meters that are used to measure the sound pressure levels of audible signals in fire alarm systems1

説明

Fire pump
エクスペリエンス
A suction in-line fire pump has a pressure range that can exceed 300 psi (2,068 kPa). This type of pump is a centrifugal pump that is installed in a vertical position with the suction and discharge connections in the same line. The pump is designed to handle high pressures and flows, and it is suitable for high-rise buildings and other applications that require high head.According to NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection, a suction in-line fire pump can have a rated pressure of up to 360 psi (2,482 kPa)1.The other types of fire pumps mentioned in the question have lower pressure ranges, as shown in the table below2:
Type of fire pump
Pressure range (psi)
Pressure range (kPa)
Horizontal-end suction
40 to 150
276 to 1,034
Split case
40 to 150
276 to 1,034
Vertical turbine
40 to 150
276 to 1,034
Suction in-line
40 to 360
276 to 2,482
References:NFPA 20: Fire pump design | Consulting – Specifying Engineer;Understanding the Basics of Fire Pumps | Pumps & Systems

説明
Probabilistic fire models are categorized into network, statistical, simulation, and behavioral models. Network models use graph theory to represent the fire spread and the fire protection system in a building. Statistical models use historical data and probability distributions to estimate the likelihood and consequences of fire scenarios. Simulation models use mathematical equations and numerical methods to describe the physical and chemical processes of fire and its effects on the environment and the occupants. Behavioral models use psychological and sociological theories to predict the human response and evacuation behavior in case of fire.
Network models are not a common category of probabilistic fire models, and they are not mentioned in the sources provided by the user. Therefore, network models are the correct answer.
References:Probabilistic Fire Simulation Assessment Using Simplified Model and Zone Modelling of a Kitchen Fire Scenario;Computer Fire Models for Fire Investigation and Reconstruction;Fire Behavior

説明
The types of overspray collectors associated with spray booths can be categorized into venturi scrubbers, waterfall scrubbers, dry filter, and cartridge filter. Venturi scrubbers use a high-velocity water spray to capture the overspray particles in a turbulent zone. Waterfall scrubbers use a curtain of water flowing over a perforated plate to wash down the overspray. Dry filter collectors use a series of filters, such as paper, fiberglass, or synthetic media, to trap the overspray. Cartridge filter collectors use pleated cartridges with high surface area and efficiency to capture the overspray. These collectors also have a self-cleaning mechanism that uses compressed air to dislodge the overspray from the cartridges.
References:Spray Booth Filters: Types and Selection;Spray Booths and Paint Finishing Operations;Spray Booth Filters: Types and Selection;Spray Booth Filters: Types and Selection;Spray Booth Filters: Types and Selection

説明
According to NFPA 70: National Electrical Code (NEC) 2020 Edition, Article 230.71(A), each service shall have only one disconnecting means unless the requirements of 230.71(B) are met, which provide four specific service configurations. In each configuration, there shall be not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, per service grouped in any one location. Therefore, the maximum number of additional switches or circuit breakers allowed for a separate service is six.References:
NFPA 70: National Electrical Code (NEC) 2020 Edition, Article 230.71(A) and (B)12 ElectricalLicenseRenewal.com, 230.71 Maximum Number of Disconnects3

説明
According to NFPA 101: Life Safety Code, 2018 Edition, the travel distance limit for a new unsprinklered educational occupancy is 175 ft. (53 m). This is the maximum distance that an occupant has to travel from any point within the building to reach an exit or exit access door. The travel distance limit for a new sprinklered educational occupancy is 250 ft. (76 m).These limits are based on the assumption that the building has at least two exits or exit access doors from each room or space12 References:
NFPA 101: Life Safety Code, 2018 Edition, Chapter 14
Deco DeD – I Dig Hardware

説明
Process safety is the type of process hazard analysis program that addresses the prevention of flammable and hazardous materials released from containment. Process safety is a discipline that focuses on the prevention and control of incidents that have the potentialto cause catastrophic consequences involving fire, explosion, or toxic release. Process safety involves the application of engineering and management principles, criteria, and techniques to identify, understand, and control process hazards. Process safety covers many aspects of a process, such as design, operation, maintenance, inspection, testing, and emergency response.
References: Process hazard analysis – Wikipedia1; What does the OSHA standard, – Occupational Safety and Health Administration2; Fire Protection Handbook, 20th Edition, Volume 1, Chapter 8, Section 8.3.13.

説明

Acetylene
エクスペリエンス
The ignition temperature of acetylene gas is 581° F (305° C). This is the minimum temperature required to ignite a gas or vapor in air without a spark or flame being present. The ignition temperature of acetylene gas varies according to composition, initial pressure, initial temperature, and water vapor content.As a typical example, an air mixture containing 30 percent acetylene by volume at atmospheric pressure can be ignited at about 581 °F (305°C)1.
References:Fuels and Chemicals – Autoignition Temperatures – The Engineering ToolBox;Ignition Temperatures and Group Classifications for Flammable Gases and Vapors;Is Acetylene Flammable? – Firefighter Insider;Ignition temperature acetylene – Big Chemical Encyclopedia;Acetylene Gas- its Characteristics and Safety Requirements

説明
0.62
The discharge coefficient of a solid stream nozzle for a standard orifice with sharp edges is a dimensionless number that indicates the ratio of the actual flow rate to the theoretical flow rate of the nozzle. The discharge coefficient depends on the geometry and the flow conditions of the nozzle. According to the web search results, the typical discharge coefficient of a solid stream nozzle for a standard orifice with sharp edges is about 0.62, which means that the actual flow rate is about 62% of the theoretical flow rate.This value is based on the experiments conducted by the National Bureau of Standards (now NIST) and reported in the paper
“Discharge Coefficients of Fire Nozzles”1.The paper also provides a formula to calculate the discharge coefficient for different nozzle diameters and pressures123

説明
Spontaneous combustion is the exception to the requirement of a combustible material, an oxidizing agent, and an ignition source for combustion to take place. Spontaneous combustion is a phenomenon in which a material can ignite without any external heat or flame, due to a chemical reaction within the material that generates enough heat to reach the ignition temperature. Spontaneous combustion can occur in certain materials that are prone to self-heating, such as oily rags, hay, coal, and compost. Spontaneous combustion is a type of smoldering combustion, which is a slow, low-temperature, flameless form of combustion.References:
Fire Protection Handbook, 20th Edition, Volume 1, Chapter 2, Section 2.2.1.11 NFPA 921: Guide for Fire and Explosion Investigations, 2021 Edition, Section 4.3.12

説明
NFPA 484: Standard for Combustible Metals, 2020 Edition, provides requirements for the storage and handling of aluminum powders, flakes, and pastes. This standard covers the production, processing, finishing, handling, recycling, storage, and use of all metals and alloys that are in a form capable of combustion or explosion. It also covers operations where metal or metal alloys are subjected to processing or finishing operations that produce combustible powder or dust.NFPA 484 includes specific chapters for various metals and alloys, including aluminum and aluminum alloys12 References:
NFPA 484: Standard for Combustible Metals
NFPA 651: Standard for the Machining and Finishing of Aluminum and the …

説明
Scenario groupings is a data analysis approach that provides the broadest perspective of a fire problem by identifying and comparing different types of fire incidents based on their characteristics, such as ignition source, fuel, location, time, and outcome. This approach can help reveal patterns, trends, and relationships among fire scenarios and support fire prevention and protection strategies.References:Fire Data Analysis Handbook, Chapter 5: Scenario Groupings; [Fire Protection Handbook], Section 2, Chapter 3: Fire Data Collection and Analysis.

説明

Fire extinguisher
エクスペリエンス
smothering.
The primary mechanism by which carbon dioxide extinguishes fire is smothering, or displacing the oxygen that the fire needs to sustain combustion. Carbon dioxide is a gas that is heavier than air, so when it is released from the extinguisher, it forms a blanket over the fire and pushes away the oxygen.Without oxygen, the fire cannot continue to burn and is extinguished1234 Cooling is a secondary mechanism by which carbon dioxide extinguishes fire. Carbon dioxide is stored as a liquid under high pressure in the extinguisher, and when it is released, it expands rapidly and cools down. The cold gas absorbs heat from the fire and lowers the temperature of the fuel below its ignition point.However, cooling is not the main effect of carbon dioxide, as it is less effective than water in reducing the heat of the fire1234 Saponification and chemical inhibition are not mechanisms by which carbon dioxide extinguishes fire.
Saponification is a process by which wet chemical agents react with fats and oils to form a soapy foam that seals the surface of the fire and prevents re-ignition. Chemical inhibition is a process by which dry chemical agents interfere with the chemical chain reaction of the fire and stop the production of free radicals that propagate the combustion.These mechanisms are used by other types of fire extinguishers, such as Class K and Class D extinguishers, respectively1234 References:
Carbon Dioxide Extinguishers – University of South Carolina4
How Does A Co2 Fire Extinguisher Work2
Why is Carbon Dioxide Used to Extinguish Oil Fires3
What is a Carbon Dioxide Fire Extinguisher?- Safeopedia1

説明
The coefficient of discharge of a fire hydrant when the outlet is smooth and well-rounded is 0.90. This is the highest coefficient given by NFPA 291 for fire hydrant outlets, and it means that the stream is almost as large as the outlet diameter. The coefficient of discharge is a factor that accounts for the difference between the actual flow and the theoretical flow from an orifice, based on the shape and condition of the outlet1. A lower coefficient means that the stream is more restricted and has a smaller cross-sectional area than the outlet. NFPA 291 provides three coefficients for fire hydrant outlets, depending on how the outlet projects into the barrel: 0.90 for smooth and well-rounded outlets, 0.80 for outlets with a hexagonal or square projection, and 0.70 for outlets with a long projection or adamaged edge2. The coefficient of discharge is used to calculate the flow rate from the pitot pressure measured at the centerline of the stream3. References:
Fire Fighting Foams – Chemguard
Guide to Hydrant Flow Testing | WSRB
New Fire Hydrant Flow Test Charts (PDF) – MeyerFire

説明
25%
Explosions or fires from flammable gas or oil fuel vapor-air mixtures may be prevented by ventilation and controls that keep the flammable vapor content below 25% of the lower flammable limit (LFL) of the vapor-air mixture, according to the web search results. The LFL is the lowest concentration of a gas or vapor in air that can produce a flash of fire in the presence of an ignition source. Below the LFL, the mixture is too lean to burn. The LFL varies for different gases and vapors, and it is usually expressed as a percentage by volume of air at 25°C and atmospheric pressure. For example, the LFL of methane is 4.4%, which means that a mixture of methane and air with less than 4.4% methane cannot ignite. To prevent explosions or fires, the concentration of flammable gases or vapors should be kept below 25% of their LFL, which is equivalent to
1.1% methane in this case. Ventilation, natural or mechanical, is one of the methods to achieve this by diluting the flammable gases or vapors with fresh air.Controls, such as gas detectors, alarms, valves, and interlocks, are another method to monitor and regulate the flammable gas or vapor levels and prevent them from reaching dangerous concentrations1234