View source for Fire hydrant

{{More citations needed|date=January 2025}}{{short description|Connection point by which firefighters can tap into a water supply}}
{{use dmy dates |date=August 2022}}
[[File:Downtown Charlottesville fire hydrant.jpg|thumb|upright|Fire hydrant in [[Charlottesville, Virginia]], United States]]
A '''fire hydrant''', '''fireplug''',<ref>{{Cite web |title=Definition of FIREPLUG |url=https://www.merriam-webster.com/dictionary/fireplug |access-date=2025-01-12 |website=www.merriam-webster.com |language=en}}</ref> '''firecock''' (archaic),<ref>{{Cite web|title=Firecock {{!}} Definition of Firecock by Oxford Dictionary on Lexico.com|url=https://www.lexico.com/en/definition/firecock|archive-url=https://web.archive.org/web/20201024214903/https://www.lexico.com/en/definition/firecock|url-status=dead|archive-date=24 October 2020|access-date=2020-10-22|website=Lexico Dictionaries {{!}} English|language=en}}</ref> '''hydrant riser''' or '''Johnny Pump'''<ref>{{Cite web |title=Brooklyn Johnny Pumps |url=https://theglorifiedtomato.com/2024/01/03/brooklyn-johnny-pumps/ |access-date=2024-09-17 |language=en-US}}</ref>{{Better source needed|date=January 2025}} is a connection point by which [[firefighter]]s can tap into a [[water supply]]. It is a component of [[active fire protection]]. Underground fire hydrants have been used in [[Europe]] and [[Asia]] since at least the 18th century. Above-ground pillar-type hydrants are a 19th-century invention.

==Operation==
The user (most likely a [[fire department]]) attaches a [[Fire hose|hose]] to the fire hydrant, then opens a [[valve]] on the hydrant to provide a powerful flow of water, on the order of {{convert|350|kPa|psi|lk=on}}; this [[pressure]] varies according to region and depends on various factors (including the size and location of the attached [[water main]]). This user can attach this hose to a [[fire apparatus|fire engine]], which can use a powerful [[pump]] to boost the [[water pressure]] and possibly split it into multiple streams. One may connect the hose with a [[threaded pipe|threaded]] connection, instantaneous "[[quick connector]]" or a [[Storz connector]].<ref>{{Cite news |last=Wesser |first=James |date=February 25, 2024 |title=How do fire hydrants work? |url=https://www.abc27.com/digital-originals/how-do-fire-hydrants-work/ |work=[[WHTM]]}}</ref>

If a fire hydrant is opened or closed too quickly, a [[water hammer]] can occur and damage nearby pipes and equipment. The water inside a charged [[Hoseline|hose line]] causes it to be very heavy, and high-water pressure causes it to be stiff and unable to make a tight turn while pressurized. When a fire hydrant is unobstructed, this is not a problem, as there is enough room to adequately position the hose.{{Clarification needed|reason=Is this sentence still about the case when the hydrant is opened or closed too quickly? Or is it a separate thought from the beginning of the paragraph?|date=January 2025}}

Most fire hydrant valves are not designed to [[throttle]] the water flow; they are designed to be operated full-on or full-off. The valving arrangement of most dry-barrel hydrants is for the drain valve to be open at anything other than full operation. Usage at partial opening can consequently result in considerable flow directly into the soil surrounding the hydrant, which, over time, can cause severe [[Hydrodynamic scour|scouring]]. [[Gate valve|Gate]] or [[Butterfly valve|butterfly valves]] can be installed directly onto the hydrant opening to control individual outputs and allow for changing equipment connections without turning off the flow to other outlets. These valves can be up to {{convert|12|in|cm}} in diameter to accommodate the large central "steamer" outlets on many US hydrants. It is good practice to install valves on all outlets before using a hydrant as the protective caps are unreliable and can cause major injury if they fail.

New [[firefighter]]s are often trained extensively on fire hydrants in the fire academy to be quick and safe while connecting the fire engine to the fire hydrant (usually within one minute). Time is often critical as other firefighters will be waiting for the water supply. When operating a hydrant, a firefighter typically wears appropriate [[personal protective equipment]], such as [[glove]]s and a [[helmet]] with [[face shield]] worn. High-pressure water coursing through a potentially aging and [[Corrosion|corroding]] hydrant could cause a failure, injuring the firefighter operating the hydrant or bystanders.

In most jurisdictions it is illegal to park a car within a certain distance of a fire hydrant. In [[North America]], the distances are commonly {{convert|3|to|5|m|ft|0}}, often indicated by yellow or red paint on the curb. The rationale behind these laws is that hydrants need to be visible and accessible in an emergency. In the event that a car is illegally parked next to a fire hydrant when firefighters need access to it, firefighters are legally allowed to break the car's windows to run the hose through it, while the car owner receives a parking citation.

<gallery mode="packed">
File:Clappered.JPG|Clapper valve
File:Hydrant to truck.jpg|A [[New York City]] hydrant hooked to an [[Fire Department of New York|FDNY]] [[fire engine]] with a [[fire hose]] actively pumping water
</gallery>

=== Other uses===

====Street pooling====
[[File:Philadelphia fire hydrant.jpg|thumb|upright|Children playing in the spray of a fire hydrant in [[Philadelphia]] (1996)]]
In 1896, during a terrible [[heatwave]] in [[New York City]], the Commissioner of [[Public Works]] ordered the opening of the fire hydrants to provide relief to the population.<ref>Marc Bettinelli [https://www.lemonde.fr/societe/video/2017/06/26/street-pooling-d-ou-vient-cette-idee-d-ouvrir-des-bouches-a-incendie-en-periode-de-canicule_5151375_3224.html « Street pooling » : d'où vient cette idée d'ouvrir des bouches à incendie en période de canicule ?] Le Monde, 26 June 2017</ref> Today some US communities provide low flow [[irrigation sprinkler|sprinkler]] heads to enable residents to use the hydrants to cool off during hot weather, while gaining some control on water usage. Sometimes those simply seeking to play in the water remove the caps and open the valve, providing residents a place to play and cool off in summer.

====Preventing misuse====
To prevent casual use or misuse, the hydrant requires special tools to be opened, usually a large wrench with a [[Pentagon|pentagonal]] socket. [[Vandalism|Vandals]] sometimes cause monetary loss by wasting water when they open hydrants. Such vandalism can also reduce municipal water pressure and impair firefighters' efforts to extinguish fires. Most fire hydrants in [[Australia]] are protected by a silver-coloured cover with a red top, secured to the ground with bolts to protect the hydrant from vandalism and unauthorized use. The cover must be removed before use.

In most areas of the [[United States]], [[General contractor|contractors]] who need temporary water may purchase permits to use hydrants. The permit will generally require a [[Water meter|hydrant meter]], a [[gate valve]] and sometimes a [[Check valve|clapper valve]] (if not designed into the hydrant already) to prevent [[backflow]] into the hydrant. Additionally, residents who wish to use the hydrant to fill their in-ground [[swimming pool]] are commonly permitted to do so, provided they pay for the water and agree to allow firefighters to [[Draft (water)|draft]] from their pool in the case of an emergency.

[[Municipal services]], such as [[street sweeper]]s and tank trucks, may also be allowed to use hydrants to fill their water tanks. Often [[sanitary sewer|sewer]] maintenance trucks need water to flush out [[sewerage]] lines and fill their tanks on site from a hydrant. If necessary, the municipal workers will record the amount of water they used or use a meter.

Fire hydrants may be used to supply water to [[riot control]] vehicles. These vehicles use a high-pressure [[water cannon]] to discourage rioting.

Since fire hydrants are one of the most accessible parts of a [[water distribution system]], they are often used for attaching pressure gauges or loggers or monitor system water pressure. Automatic flushing devices are often attached to hydrants to maintain chlorination levels in areas of low usage. Hydrants are also used as an easy above-ground access point by leak detection devices to locate leaks from the sound they make.

==Construction==
[[File:Hydrantandcb.jpg|right|thumb|Hydrant installation in [[Ontario]], Canada]]
[[File:Reduced pressure zone device connected to a fire hydrant at a construction site.jpg|thumb|A [[reduced pressure zone device]] is used to prevent [[backflow]] when supplying water to a construction site]]
Depending on the country or location, hydrants can be above or below ground. In countries including [[Japan]], the [[United Kingdom|UK]], [[Ukraine]], [[Russia]] or [[Spain]] hydrants are accessible under a heavy metal cover. In other countries, such as the US, and many parts of [[China]], an accessible part of the hydrant is above ground. It can also be mounted in an exterior wall of a building.

In areas subject to freezing temperatures, at most only a portion of the hydrant is above ground. The valve is located below the [[frost line]] and connected by a [[wikt:riser|riser]] to the above-ground portion. A valve rod extends from the valve up through a seal at the top of the hydrant, where it can be operated with the proper [[wrench]]. This design is known as a "dry barrel" hydrant, in that the barrel, or vertical body of the hydrant, is normally dry. A drain valve underground opens when the water valve is completely closed; this allows all water to drain from the hydrant body to prevent the hydrant from freezing.

In warm areas, above-ground hydrants may be used with one or more valves in the above-ground portion. Unlike with cold-weather hydrants, it is possible to turn the water supply on and off to each port. This style is known as a "wet barrel" hydrant.

Both wet- and dry-barrel hydrants typically have multiple outlets. Wet barrel hydrant outlets are typically individually controlled, while a single stem operates all the outlets of a dry barrel hydrant simultaneously. Thus, wet barrel hydrants allow single outlets to be opened, requiring somewhat more effort, but simultaneously allowing more flexibility.

A typical US dry-barrel hydrant has two smaller outlets and one larger outlet. The larger outlet is often a [[Storz]] connection if the local fire department has standardized on hose using [[Storz]] fittings for large diameter supply line. The larger outlet is known as a "steamer" connection, because they were once used to supply steam powered water pumps, and a hydrant with such an outlet may be called a "steamer hydrant", although this usage is becoming archaic. Likewise, an older hydrant without a steamer connection may be called a "village hydrant."

==Appearance==
[[File:Kawaii fire hydrant cover in Tokyo, Shinbashi.jpg|thumb|[[Kawaii]] fire hydrant cover in [[Shinbashi]], Tokyo]]
Above-ground hydrants are coloured for visibility, to signal their characteristics, or for aesthetics. In the United States, the [[American Water Works Association|AWWA]] and [[National Fire Protection Association|NFPA]] recommend hydrants be colored chrome yellow<ref>{{cite web|title=National Fire Protection Association Report (p. 18)|url=http://www.nfpa.org/Assets/files/AboutTheCodes/24/24_AUT_PRI_A2015_FReport01.pdf |work=[[National Fire Protection Association]] (NFPA) |date=August 15, 2013|quote=''All barrels are to be chrome yellow except in cases where another color has already been adopted''.}}</ref> for rapid identification apart from the bonnet and nozzle caps which should be coded according to their available flow. Class AA hydrants (>1500&nbsp;[[gallons per minute|gpm]]) should have their nozzle caps and bonnet colored light blue, Class A hydrants (1000–1499&nbsp;gpm) green, Class B hydrants (500–999&nbsp;gpm) orange, Class C hydrants (0–499&nbsp;gpm) red, and inoperable or end-of-system (risking water hammer) black. These aids arriving firefighters in determining how much water is available and whether to call for additional resources or find another hydrant.

Other codings can be and frequently are used, some of greater complexity, incorporating pressure information, others more simplistic. In [[Ottawa]], [[Ontario]], hydrant colors communicate different messages to firefighters; for example, if the inside of the hydrant is corroded so much that the interior diameter is too narrow for good pressure, it will be painted in a specific scheme to indicate to firefighters to move on to the next one. In many localities, a white or purple top indicates that the hydrant provides [[Drinking water|non-potable]] water. Where artistic and/or aesthetic considerations are paramount, hydrants can be extremely varied, or more subdued. In both instances this is usually at the cost of reduced practicality.

In [[Germany]], the [[Netherlands]], [[Spain]], the [[United Kingdom|UK]], and many other countries, most hydrants are located below ground and are reached by a riser, which provides the connections for the hoses. The covers can also be artistically designed.

<gallery mode="packed" heights="180px">
File:Fire-hydrant-demorest.jpg|Hydrant in the [[United States]] painted with an [[United States|American]] patriotic theme
File:Fire hydrant in Bonifacio Global City.jpg|Hydrant in the [[Philippines]]
File:Standrohr unterflurhydrant.jpg|[[Germany|German]] underground hydrant with [[Storz]] hose connections
File:Hydrant Fredantori Helsinki.jpg|Hydrant at Fredantori square in [[Helsinki]], [[Finland]]
File:Požární hydrant.jpg|[[Czech Republic|Czech]] example
File:Greek fire hydrant.jpg|[[Greece|Greek]] example
File:Red fire hydrant in Lisbon 01.jpg|[[Portugal|Portuguese]] example
File:Hidrante.jpg|[[Brazil|Brazilian]] example
File:Unterflurhydrant 100 0477.jpg|[[Germany|German]] underground example
File:Boca de incendio Barcelona España 1.jpg|Spanish cover in [[Barcelona|Barcelona, Spain]]
File:Fire hydrant at the University of Victoria, BC (DSCF5631).jpg|Fire hydrant in [[British Columbia]]
File:1869BirdsillHollyHydrantSideTop.jpg|[[Birdsill Holly]] hydrant side view from city water supply pipeline right-of-way land
File:Holly 4 sided top nut.jpg|[[Birdsill Holly]] hydrant top view with description and patent date information
File:Left nozzel.JPG|2016 modern fire hydrant
File:Forward nozzel.JPG|Forward hydrant nozzle
File:2016 fire-hydrant.JPG|Hydrant nozzle side view
File:Hydrant 5 sided top nut.jpg|Fire hydrant 5 sided top nut
Stettenfels Hydrant v.jpg|Big pipe hydrant
File:Fireman uses hydrant.jpg|Fireman uses hydrant
</gallery>

==Signage==
In the [[United Kingdom]] and [[Republic of Ireland|Ireland]], hydrants are located in the ground.<ref>BS 750: "Specification for underground fire hydrants and surface box frames and covers" (2012).</ref> Yellow "H" hydrant signs indicate the location of the hydrants and are similar to the blue signs in [[Finland]]. Mounted on a small post or nearby wall etc., the two numbers indicate the diameter of the water main (top number) and the distance from the sign (lower number). Modern signs show these measurements in millimetres and metres, whereas older signs use inches and feet.<ref>{{cite web|title=Good Stewardship for Schools Premises p. 18|url=http://www.cambridgeshire.gov.uk/NR/rdonlyres/C39CB426-397F-43D0-8D3F-31637BE56C3E/0/GSGuidefoSchools2009.pdf|publisher=Cambridgeshire County Council|date=2009|archive-url=https://web.archive.org/web/20120304173525/http://www.cambridgeshire.gov.uk/NR/rdonlyres/C39CB426-397F-43D0-8D3F-31637BE56C3E/0/GSGuidefoSchools2009.pdf|archive-date=March 4, 2012}}</ref> Because the orders of magnitude are so different (6&nbsp;inches versus 150&nbsp;mm) there is no ambiguity whichever measuring system is used.

In areas of the [[United States]] without winter snow cover, blue [[raised pavement marker#Reflective raised pavement markers|reflectors]] embedded in the street are used to allow rapid identification of hydrants at night. In areas with snow cover, tall signs or flags are used so that hydrants can be found even if covered with snow. In [[rural]] areas tall narrow posts painted with visible colours such as red are attached to the hydrants to allow them to be found during heavy snowfall periods. The tops of the fire hydrants indicate available flow in gallons per minute; the color helps make a more accurate choice of what hydrants will be utilized to supply water to the fire scene.<ref name=trict>{{cite web|last1=Lamm|first1=Willis|title=Hydrant color codes and markings|url=http://www.firehydrant.org/info/hycolor.html |year=2001 |website=Fire hydrant.org|publisher=Water supply office|access-date=31 March 2015}}</ref>

*Blue: {{convert|1500|USgal/min|impgal/min L/s|0|lk=on}} or more; very good flow
*Green: {{convert|1000|-|1499|USgal/min|impgal/min L/s|0}}; good for residential areas 
*Orange: {{convert|500|–|999|USgal/min|impgal/min L/s|0}}; marginally adequate
*Red: below {{convert|500|USgal/min|impgal/min L/s|0}}; inadequate

The hydrant bodies are also color-coded.

*Chrome Yellow: Municipal System
*Red: Private System
*Violet: Non-potable supply
 
These markings and colours are prescribed in ''[[National Fire Protection Association|NFPA]] 291: Recommended Practice for Water Flow Testing and Marking of Hydrants''. but most municipal water authorities do not actually follow these guidelines.<ref>{{cite web |url=https://www.muellercompany.com/sites/muellercompany.com/files/uploads/media/mueller_wp17303_paintingfirehydrants_f13807_v8.pdf |title=The Proper Painting of Fire Hydrants for Maintenance and Color Classification |access-date=August 14, 2022}}</ref>

In [[Australia]], hydrant signage varies, with several types displayed across the country. Most Australian hydrants are underground, being of a [[ballcock]] system (spring hydrant type), and a separate standpipe with a central plunger is used to open the valve. Consequently, hydrant signage is essential, because of their concealed nature.
* Painted markers{{snd}}Usually a white or yellow (sometimes reflective paint) triangle or arrow painted on the road, pointing towards the side of the road the hydrant will be found on. These are most common in old areas, or on new roads where more advanced signs have not been installed. These are almost always coupled with a secondary form of signage.
* Hydrant Marker Plates{{snd}}Found on power poles, fences, or street-signs, these are a comprehensive and effective system of identification. The plate consists of several codes; H (Potable water Hydrant), RH (Recycled/Non-Potable), P (Pathway, where the hydrant cover can be found), R (Roadway). The plate is vertically oriented, around 8&nbsp;cm wide, and 15&nbsp;cm high. It usually faces in the direction of the hydrant. Found on this plate, from top to bottom, are the following features:
** The codes listed above, Potable/Non-potable at the top, Path/Roadway on the bottom of the plate.
** Below this, a number giving the distance to the hydrant (in meters), then a second number below that giving the size (in millimeters) of the water main.
** A black line across the center of the plate indicates the hydrant is found on the opposite side of the road to which the plate is affixed.
** Plates for recycled water have a purple background, as well as the RH code, normal potable hydrants are white, with the H code.
* [[Raised pavement marker|Road markers]] or [[Cat's eyes (road)|Cat's eyes]]{{snd}}Almost exclusively blue, these are placed on one side or the other of the centre line of the road, to indicate on which side of the road the hydrant lies. They are visible for several hundred meters at night in heavy rain, further in clear conditions.

In [[Germany]] the hydrant marker plates follow the style of other marker plates pointing to underground installations. Fire hydrant marker plates have a red border. Other water hydrants may have a blue border. A gas hydrant would have a yellow background instead of a white one for fire hydrants. All of them have large central T with the installation identification on top of it{{snd}}an "H" or older "UH" is located in the ground, a "OH" is above ground, followed by the pipe inner diameter in millimeters (with a small 80&nbsp;mm in residential areas). The numbers around the T allow to locate the installation in reference to the plate's location{{snd}}the number left of the T is in meter left of the sign, the number right of the T is in meter right of the sign, and number below the T tells the distance in meter in front of the sign, where a negative number would point to a place behind the sign. The distance numbers are always given with a comma decimeter precision. If it is not a common fire hydrant type then another identification may be used, for example "300 m³" would point to a cistern usable to pump water from.

In [[East Asia]] ([[China]], [[Japan]] and [[South Korea]]) and former [[Socialism|Socialist]] countries of [[Eastern Europe]], there are two types of fire hydrants, of which one is on the public ground and the other inside a building. The ones inside a building are installed on a wall. They are big, rectangular boxes that also provide alarms (sirens), a fire extinguisher and, at certain times, emergency kits.

<gallery mode=packed heights=150px>
File:1858 FC plaque.jpg|Hydrant sign in [[Cork (city)|Cork, Ireland]], dated 1858. The letters "FC" indicate the old name for a hydrant: ''[[Wiktionary:firecock|firecock]]''.
File:Fire hydrant UK (cropped).jpg|British fire hydrant and sign{{snd}}the sign indicates the hydrant is 100&nbsp;mm in diameter and 1 metre from the sign
File:Birmingham Fire hydrant cover - 2020-07-24 - Andy Mabbett.png|'[[Birmingham City Council|Corporation of Birmingham]]' hydrant cover, [[England]], circa 1920s
File:Fire hydrant in Korolyov.jpg|Underground hydrant in [[Russia]], marked with a plate and a red cone
File:Hydrantenschild_rot_und_blau.jpg|Red fire hydrant marker plate in [[Germany]], along with another blue special-purpose water hydrant marker plate{{snd}}The numbers indicate the diameter (80&nbsp;mm) and the location (2.8 meter in the back, 1.5 meter to the right).
File:Fire_Hydrant_and_blue_reflector.jpg|A blue reflector marks the location of the fire hydrant
</gallery>

==Inspection and maintenance==
In most areas, fire hydrants require annual inspections and maintenance; they normally only have a one-year warranty, but some have 5- or even 10-year warranties, although the longer warranty does not remove the need for periodic inspections or maintenance. These inspections are generally performed by the local municipalities or fire departments, but they often do not inspect hydrants that are identified as private. Private hydrants are usually located on larger properties to adequately protect large buildings in case of a fire and in order to comply with the [[fire code]]. Such hydrants have met the requirements of insurance underwriters and are often referred to as UL/FM hydrants. Usually, companies are contracted out to inspect private fire hydrants, unless the [[municipality]] has undertaken that task. 

Some fire hydrant manufacturers recommend lubricating the head mechanism and restoring the [[Head gasket|head gaskets]] and [[O-ring|O-rings]] annually in order that the fire hydrant perform the service expected of them, while others have incorporated proprietary features to provide long-term lubrication of the hydrant's operating mechanism. In any case, periodic inspection of lubricants is recommended. [[Lubrication]] is generally done with a food-grade non-petroleum lubricant to avoid contamination of the distribution system.

Occasionally a stone or foreign object will mar the seat gasket. In this case, most hydrants have a special seat wrench that allows removal of the seat to replace the gasket or other broken parts without removing the hydrant from the ground. Hydrant extensions are also available for raising a hydrant if the grade around the hydrant changes. Without extending the height, the wrenches to remove caps would not clear and the break flanges for traffic models would not be located correctly in case they were hit. Hydrant repair kits are also available to repair sacrificial parts designed to break when hit by a vehicle.

Many [[Fire department|fire departments]] use the hydrants for flushing out water line sediments. When doing so, they often use a hydrant diffuser, a device that diffuses the water so that it does not damage property and is less dangerous to bystanders than a solid stream. Some diffusers also [[dechlorinate]] the water to avoid ground contamination.<ref>{{cite web|url=http://www.ashevillenc.gov/Portals/0/city-documents/Water/Hydrant_Flushing_FAQ%281%29.pdf|title=Hydrant Flushing FAQ, United States of America|access-date=12 March 2012|archive-date=6 October 2011|archive-url=https://web.archive.org/web/20111006125858/http://ashevillenc.gov/Portals/0/city-documents/Water/Hydrant_Flushing_FAQ(1).pdf|url-status=dead}}</ref> Hydrants are also sometimes used as entry or exit points for [[pigging|pipe cleaning pigs]].

In 2011, [[Code for America]] developed an "Adopt a Hydrant" website, which enables volunteers to sign up to shovel out fire hydrants after snowstorms. As of 2014, the system has been implemented in [[Boston]]; [[Providence, Rhode Island]]; [[Anchorage, Alaska]]; and [[Chicago]].<ref>{{Cite news| last = Raja| first = Tasneem| title = Is Coding the New Literacy?| work = [[Mother Jones (magazine)|Mother Jones]]| access-date = 2014-06-21| date = 2014| url = https://www.motherjones.com/media/2014/06/computer-science-programming-code-diversity-sexism-education}}</ref>

<gallery mode="packed" heights="150px">
File:Hydrantenschluessel Oberflur gross.jpg|Fire hydrant wrench ([[Germany]])
File:Fire hydrant knocked over.jpg|A fire hydrant that was hit by a snowplow and knocked over, damaging only the sacrificial bolts
File:2011-02-12 Fire hydrant flushing 1.jpg|A fire hydrant flushing water through a diffuser in [[Durham, North Carolina]]
File:Fire hydrant flushing rusty water.jpg|A fire hydrant without a diffuser, flushing discolored water
File:Fire hydrant inspection by firefighters in Oklahoma.jpg|Hydrant testing by firefighters
</gallery>

==Non-pressurized (dry) Hydrants {{anchor|DRY|Fire pond}}==
[[File:Dry Fire Hydrant in East Haven, Vermont April 2018.jpg|thumb|upright|A dry hydrant by [[Passumpsic River]] in rural [[Vermont]]]]
In rural areas where municipal water systems are not available, dry hydrants are used to supply water for fighting fires. A dry hydrant is analogous to a [[standpipe (firefighting)|standpipe]]. A dry hydrant is usually an unpressurized, permanently installed pipe that has one end below the water level of a lake or pond. This end usually has a strainer to prevent debris or wildlife, such as fish, from entering the pipe. The other end is above ground and has a hard sleeve connector.

When needed, a pumper fire engine will pump from the lake or pond by [[drafting water]]. This is done by vacuuming the air out of the dry hydrant, hard sleeve, and the fire engine pump with a primer. Because lower pressure now exists at the pump intake, atmospheric pressure on the water and the weight of the water forces water into the above-water portion of the dry hydrant, into the hard sleeve, and finally into the pump. This water can then be pumped by the engine's [[centrifugal pump]].

==Other types==
*[[Water wells]] are also sometimes classified as fire hydrants if they can supply enough water volume and pressure.
*[[Standpipe (firefighting)|Standpipe]]s are connections for firehoses within a building and serve the same purpose inside larger structures as fire hydrants do outdoors. Standpipes may be "dry" or "wet" (permanently filled with water); a dry standpipe requires an external source of water such as firefighting equipment.

==History==
Before piped mains supplies, water for firefighting had to be kept in buckets and cauldrons ready for use by '[[Bucket brigade|bucket-brigades]]' or brought with a horse-drawn fire-pump. From the 16th century, as wooden [[mains water]] systems were installed, [[firefighters]] would dig down to the pipes and drill a hole for water to fill a “wet well” for the buckets or pumps. This had to be filled and plugged afterwards, hence the common US term for a hydrant, 'fireplug'. A marker would be left to indicate where a 'plug' had already been drilled to enable firefighters to find ready-drilled holes. Later wooden systems had pre-drilled holes and plugs.<ref>{{usurped|1=[https://web.archive.org/web/20150912094219/http://www.sewerhistory.org/photosgraphics/pipes-wood/ The History of Sanitary Sewers]}} Retrieved August 2019</ref>

When [[cast iron]] pipes replaced the wood, permanent underground access points were included for the fire fighters. Some countries provide access covers to these points, while others attach fixed above-ground hydrants{{snd}}the first cast iron ones were patented in 1801 by [[Frederick Graff]], then chief-engineer of the Philadelphia Water Works. Invention since then has targeted problems such as tampering, freezing, connection, reliability etc.<ref>[http://www.firehydrant.org/info/ Firehydrant.org] Accessed Aug 2019</ref>

<gallery mode=packed heights=150px>
File:Wooden fire plug, New Orleans, c 1900.png|Old style wooden "fire plug" still in use {{circa|1900}}
File:L-Hydrant.png|Cast iron hydrant, 1904
</gallery>

==See also==
{{Commons and category|Fire hydrant|Fire hydrants}}
{{div col|colwidth=23em}}
*[[Active fire protection]]
*[[Birdsill Holly]]
*[[Fire extinguisher]]
*[[Fire hose]]
*[[Fire protection]]
*[[Fire sprinkler]]
*[[Flushing hydrant]]
*[[Hydrant wrench]]
*[[Portable water tank]]
* [[Stanchion#Stanchions to locate fire hydrants under deep snow|Under snow locators]]
{{div col end}}

==References==
{{Reflist}}

==Sources==
*{{cite book|last=Hinds|first=Conrade C. |title=The Great Columbus Experiment of 1908: Waterworks that Changed the World|url=https://books.google.com/books?id=0ZF2CQAAQBAJ&q=Lockport%2C+New+York%2C+was+the+first+city+to+employ+this+system&pg=PT32|date=9 October 2012|publisher=Arcadia Publishing|isbn=978-1-61423-685-6}}
*[https://www.thesaurus.com/browse/fire-hydrant (29/5/2024) https://www.thesaurus.com/browse/fire-hydrant]

==Further reading==
*{{US patent|909}} — Issued to John Jorden on September 8, 1838, for "...a new and useful improvement in Fire-Plugs and Hydrants...". This is an early wooden bodied hydrant, the earliest hydrant patent extant; the [[patent office]] itself burned to the ground in 1836, taking with it all prior hydrant patents.
*{{US patent|37466}} — Issued to Richard Stileman on January 20, 1863. An early iron hydrant, believed the first patented hydrant with the larger size '''steamer port''' to supply steam fire engines. Manufactured and marketed as the Stileman hydrant. See also [http://www.firehydrant.org/pictures/stileman.html Stileman page at FireHydrant.org].
*{{US patent|80143}} — Issued to Zebulon Erastus Coffin on July 21, 1868. This is a cast iron hydrant very similar to modern fire hydrants, it was produced by Boston Machine Co. See also [http://www.firehydrant.org/pictures/boston-machine.html Boston Machine page at FireHydrant.org].
*{{US patent|94749}} — Issued to Birdsill Holly on September 14, 1869. See also [http://www.firehydrant.org/pictures/holly.html Holly page at FireHydrant.org].
*Wohleber, Curt. [https://web.archive.org/web/20100428162059/http://www.americanheritage.com/articles/magazine/it/2002/3/2002_3_10.shtml "The Fire Hydrant"]. In ''[https://web.archive.org/web/20051230102554/http://inventionandtechnology.com/ The American Heritage of Invention & Technology]''. Winter 2002. Provides a history with dates of fire hydrant development. (Archived from [https://web.archive.org/web/20100428162059/http://www.americanheritage.com/articles/magazine/it/2002/3/2002_3_10.shtml the original] on April 28, 2010)

==External links==

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