Fire Hydrant system

A fire hydrant, (also known as fire pumps, hydrant boosters, fire water pumps)is a connection point by which firefighters can tap into a water supply.
These are high pressure water pumps designed to increase the fire fighting capacity of a building by boosting the pressure in the hydrant service when mains is not enough, or when tank fed.

A Fire Hydrant with fully-on valve , releasing pressure water.

Safe Operating Procedure- Fire Hydrant

The user attaches a hose to the fire hydrant, then opens a valve on the hydrant to provide a powerful flow of water.  Most fire hydrant valves are not designed to throttle the water flow; they are designed to be operated either full-on or full-off.

Attaching Hose with Fire Hydrant

When a firefighter is operating a hydrant, he or she typically wears appropriate personal protective equipment, such as gloves and a helmet with face shield worn. High-pressure water coursing through
a potentially aging and 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 3 to 5 m or 10 to 15 ft, often indicated by yellow or red paint on the curb. The reason behind these laws is that hydrants need to be visible and accessible in an emergency.

Hydrant Color Coding 

Hydrant-Green color

Hydrant coloring may be due to either purely practical criteria or more artistic. In the United States, the AWWA and NFPA(National Fire Protection Assocation) recommend hydrants be colored chrome yellow for rapid identification apart from the bonnet and nozzle caps which should be coded according to their available flow. Class AA hydrants (>1500 gpm) should have their nozzle caps and bonnet colored light blue, Class A hydrants (1000–1499 gpm) green, Class B hydrants (500–999 gpm) orange, Class C hydrants (0–499 gpm) red and inoperable or end-of-system (risking water hammer) black. This aids arriving firefighters in determining how much water is available and whether to call for additional resources, or find another hydrant

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. Some fire hydrant manufacturers recommend lubricating the head mechanism and restoring the head gaskets and 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.
Watch this short video for correct inspection and use of hydrant system:
https://www.youtube.com/watch?v=HTIBkvDy3vk

Dry Hydrant 

Dry hydrant pipe

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. A dry hydrant is usually an unpressurized, permanently installed pipe that has one end below the water level of a lake or pond.The other end is above ground. 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.

Standpipes

Standpipes are connections for firehoses within a building and serve the same purpose as fire hydrants in larger structures. Standpipes may be "dry" or "wet" (permanently filled with water).

Stand Pipe-Vertical

Note:

- GPM means Gallon Per Minute.
- For Water-Based Fire Protection Systems, check NFPA Code- 13, 14 and 291.

Following are some NFPA-1 standards related to fire hydrant:

• 18.5.7 Clear Space Around Hydrants.
• 18.5.7.1 A 36 in. (914 mm) clear space shall be maintained around the circumference of fire hydrants except as otherwise required or approved. 
• 18.5.7.2 A clear space of not less than 60 in. (1524 mm) shall be provided in front of each hydrant connection having a diameter greater than 21⁄2 in. (64 mm).

NFPA-24

• 6.2.10 All control valves shall be located where readily accessible and free of obstructions.

Hope you've fund this articles very informative.