World Library  
Flag as Inappropriate
Email this Article

Fog nozzle

Article Id: WHEBN0006768960
Reproduction Date:

Title: Fog nozzle  
Author: World Heritage Encyclopedia
Language: English
Subject: Firefighter, Impulse Fire Extinguishing System, Miami Fire-Rescue Department, Firefighting, Rollover (fire)
Collection: Firefighting Equipment, Nozzles
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Fog nozzle

A fog nozzle

A fog nozzle is a firefighting hose spray nozzle that breaks its stream into small droplets. By doing so, its stream achieves a greater surface area, and thus a greater rate of heat absorption, which, when compared to that of a smoothbore nozzle, speeds its transformation into the steam that smothers the fire by displacing its oxygen. Specially designed fog nozzles (with no stream adjustment) have been certified by Underwriters Laboratories (UL) for use on Class B & C hazards.

Contents

  • Roles 1
  • Variations 2
  • Pattern 3
  • Images 4
  • See also 5
  • References 6

Roles

Fog nozzles play an important part in firefighting tactics due to their versatility. The wide variety of fog nozzle manufacturers allows them to accommodate different sizes of fire hose- most often attack hand line- and streams and are capable in both fire protection and attack. With regard to flow rate, it is imperative to be sure that each fog nozzle be able to handle the flow rate of its water supply because the master stream devices to which they are sometimes attached can expel up to 2,000 US gallons (7.6 m3) per minute. Nevertheless, as with almost all fog nozzles, those on master stream devices come with either automatic or manual spray pattern and stream adjustments. However, one significant disadvantage of fog nozzles is that Compressed Air Foam (CAF) bubbles' ratio of surface area to volume (which are formed by mixing air into a solution of water and foaming agents at the pump) exceeds that of fog nozzles' water droplets; therefore, the mechanical deflection in the nozzles themselves causes a loss of bubble structure, thereby reducing the CAF's ability to absorb heat. Despite this drawback, provided an appropriate nozzle pressure and water supply, fog nozzles are effective for any ground fire situation.

Variations

Fog nozzles come in many in different styles and sizes, but there are three types which encompass most: automatic, selectable, and manually adjustable. All contain an adjustable baffle that, like a thumb placed on the end of a garden hose, keeps their flow rates and stream reaches steady and finely adjustable despite variations in water pressure at the nozzle. To adjust the flow, the first two types use a control handle, or 'bale' located at the top of nozzle; however, selectable nozzles have a fixed set of flow rates (e.g., 60, 95, and 125 GPM) that are chosen with a ring or bezel located at their tips. It is important to note that selectable nozzles will only flow if the pump pressure exceeds the nozzle pressure. Moreover, the selectable nozzle will change its nozzle pressure and reach as the handle is moved, but the automatic nozzle will automatically re-adjust its opening as the firefighter adjusts its flow rate in order to maintain the correct pressure.

Pattern

All styles of fog nozzles have a spray pattern adjustment. These nozzles can produce three different types of streams; the straight stream for long reach, the narrow-angle cone for advancing an attack line into a structure or fire room, and the wide-angle cone for protection and ventilation.

Images

See also

References

  • Fundamentals of Fire Fighting Skills. Sunbury: Jones and Bartlett Publishers, Inc. 2004. 
  • Hall, Richard, and Barbara Adams (1998). Essentials of Fire Fighting. 6th ed. Stillwater: Fire Protection Publications, Oklahoma State University. 
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.