FIR201 Assignment 5A

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Eastern Gateway Community College *

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201

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Mechanical Engineering

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Feb 20, 2024

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1 Fire Streams and Nozzles Bobby Roseberry Fire Science Department, Eastern Gateway Community College FIR 201 Fire Service Hydraulics Professor Mansfield November 26, 2023
2 Fire Streams and Nozzles The type of fire nozzle being used will determine what type of fire stream can be produced from the nozzle. Each nozzle type and fire stream will have its own advantages and disadvantages. Firefighters will have a working knowledge of which nozzle and fire stream is best suited for the type of fire they are carrying out suppression tactics on. The purpose of this paper is to identify and discuss the types of nozzles, the specific fire streams each nozzle produces, the advantages and disadvantages of each type of nozzle and fire streams, and to identify and describe the difference between the nozzle pressure and nozzle reaction. Literature Review The National Fire Protection Association (NFPA) set standards for equipment to be used in the fire service. NFPA 1964: Standard for Spray Nozzles and Appliances set the standard for the manufacturing of nozzles. The two basic types of nozzles that will be found in the fire service are, smoothbore/solid stream and fog/combination nozzles. However within the fog/combination nozzle category there are actually 3 different nozzles that can be found. Those nozzles are the fixed-gallonage combination fog nozzles, selectable-gallonage nozzles, and the automatic fog nozzles. The smoothbore nozzles can have either a short tip or longer tip, they have no internal parts other than the valve assembly that opens and closes the nozzle. They produce a solid stream that is considered to have better penetration than a fog nozzle that is set on a straight stream. The smoothbore nozzle steam is less affected by the wind (Crapo, 2017). Fixed-gallonage combination fog nozzles has a rated stem inside the fog nozzle tip, along with a valve assembly that shuts the water flow on and off, and a fog pattern selector that can be rotated by the operator. This type of nozzle keeps a fixed flow rate as the pattern selector is turned. These nozzles are best used in hydraulic ventilation tactics, vapor suppressions, and specialized delivery tactics due to the ability to deliver water in a fog pattern that absorbs heat (Bettinazzi, 2023). Selectable- gallonage nozzles are a combination fog nozzle that is equipped with a selectable ring for
3 choosing gallonage that is located between the valve and internal nozzle stem (Bettinazzi, 2023). The operator can turn the ring to select a specific flow needed but can not change the fixed nozzle pressure. The best use of this nozzle is for foam operations (Bettinazzi, 2023). Last nozzle is the automatic fog nozzle, they are different from the other two nozzles in the way they operate. They do not operate in a set flow rate, instead they operate in a variable flow rate or flow range throughout a rated operating pressure (Bettinazzi, 2023). Each type of nozzle has its own advantages and disadvantages. All three types of fog nozzles do share one common disadvantage. Smoothbore nozzle advantages are they are low cost, come in multiple sizes, they have good reach and penetration, operate at low pressure, they can easily pass debris, they do not contain moving parts, they are easy to operate, and have low reaction force. The disadvantages include they do not have variable streams, poor foam production, poor hydraulic ventilation, and the pattern must be broken by nozzle movement to increase heat absorption (Firefighter Nation Staff, 2012). Fixed-gallonage fog nozzle advantages include the option at variable streams to include straight, narrow fog and wide fog, decent foam production,decent reach abilities, low pressure operation, produces less nozzle reaction, is rugged, easy to operate, and costs less than other fog versions. The disadvantages for the fixed- gallonage fog nozzle are can not pass debris easily, has moving parts inside nozzle that may lead to mechanical failure, can have water deposits that affect operation, high pressure versions can have poor flow at low pressure, and they are larger, bulkier,heavier than smoothbore counterparts (Firefighter Nation Staff, 2012). Selectable-gallonage fog nozzles advantages include the following: they produce high gallons per minute at low nozzle pressure, they have high heat absorption abilities, and have minimal back pressure or reaction force. The disadvantages for the selectable-gallonage nozzles are they cost more, do not have variable streams, and are larger, bulkier, and heavier than smoothbore counterparts (Firefighter Nation Staff, 2012). Automatic fog nozzle advantages are, they have decent reach capabilities, have variable stream
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4 patterns,such as straight, narrow fog, and wide fog, have good foam production, are rugged and easy to use, and have constant nozzle production. The disadvantages include, they are the most expensive nozzle, can have varying gallons per minute without regular maintenance, does not have good stream production at low gpm, will shut off or may not even open at low nozzle pressure, has poor flow at low nozzle pressure, and is larger, bulkier, and heavier than smoothbore counterpart (Firefighter Nation Staff, 2012). Nozzle pressure and nozzle reaction are two very important things that a pump operator must understand. They are two separate concepts in the firefighting operateration. Nozzle pressure is the pressure that comes out of the nozzle that produces an effective fire stream needed for fire suppression operations. Where nozzle reaction is the force exerted on the firefighter that is operating the nozzle that is created by the water stream as it exits the nozzle. Conclusion With all the different types of nozzles that are available in the fire service it is important for all firefighters to understand which nozzles their department uses and the location of each nozzle. Once learning this information it is a good idea to understand what all the advantages are and the best uses of each nozzle. If firefighters know what nozzles they have the trucks equipped with and the best uses of each nozzle they will be assembled to determine which nozzle to grab at each fire for the most part.
5 References Bettinazzi, V. (2023, November 13). Nozzles 101: Smooth-bore vs. combination/fog nozzle. FireRescue1. https://www.firerescue1.com/making-the-cut-the-definitive- guide-to-firefighting-tools/nozzles-101-smooth-bore-vs-combination-fog-nozzle Crapo, W. F. (2017). Fire protection hydraulics and water supply (3rd ed.). Jones & Bartlett. Firefighter Nation Staff. (2012, June 21). Nozzle Types, Pros and Cons. FirefighterNation. https://www.firefighternation.com/firerescue/nozzle-types-pros-and-cons/#gref