Fire hydrants are an essential part of keeping property and individuals safe during a fire. Firefighters connect a hose to hydrants and access the municipality’s pressurized water system. This access allows them to pump high volumes of water to extinguish fires quickly.
Many people can easily recognize fire hydrants. After all, they are meant to stand out. But few people know much more about them than that. Hydrants are much more intricate than they appear.
Wet and Dry Barrel Fire Hydrants
Most fire hydrants extend several feet into the ground. And generally speaking, there are two primary types – wet and dry barrel hydrants. The differences between the two types are related to temperature. Wet barrel hydrants can freeze more easily than dry barrel ones. For this reason, dry barrel hydrants are more common in colder climates.
For both types, the part that can be seen contains a control valve nut and hose parts. Most hydrants have 2.5” ports and 4.5” ports to accommodate both the hose and the steamer line that goes to the fire engine. The part contained below ground has a barrel and valve. These parts are connected to the upper part with break-way flanges on the casting and break-away coupling on the operating rod. It connects to the water main using an elbow. Gate valves or pressure valves can be used to isolate a hose line if a hydrant becomes stuck open. Butterfly valves may also be located somewhere in the water system to direct the flow of water.
Wet barrels hydrants are more common in southern climates with little risk of freezing. They have the potential to operate for a century when properly maintained. All of the mechanical parts of this type of hydrant are located above ground. This means that water is the main supplying the hydrant is present and close to the surface. And while this is convenient when fighting a fire, it can make them susceptible to freezing.
Most fire hydrants in the United States are dry barrel fire hydrants. They are similar to wet barrel hydrants, but the valve remains dry when not in use. The water valve for the hydrant is located far below ground. It is kept below the frost line to ensure that the system doesn’t freeze. Maintenance of dry barrel fire hydrants includes using a plumb line to check for moisture, which would indicate a problem. The absence of water also reduces corrosion inside and leakage from the hydrant head.
While these are the primary types of fire hydrants for most locations, there are additional options, such as:
- Flush hydrants: While similar to a regular fire hydrant, these have one port that functions as a wide-open outlet. These hydrants are used for flushing out water mains and empty to a waterway or storm drain.
- Post hydrants: These hydrants extend in a straight line from the ground at the top of a feed pipe. Since the outlet and handle are elevated at approximately 3 feet, they appear like posts. Post hydrants are found on large campuses and facilities. They are handle operated and contain a valve located below the frost line.
- Standpipes: These hydrants are a bit different than others as they are typically located inside a building. Their configuration allows firefighters to distribute water to defined areas of the building, often allowing people trapped to exit the building.
With several variations of fire hydrants, selecting the right one requires planning and consideration. It should also be noted that hydrants come in a range of colors. Usually, red or green is selected to make them stand out. However, some cities have color schemes that can provide information about the pressure available at each hydrant. The caps on the hydrant can also give pressure information. These caps are a nut most often shaped as a pentagon. Yellow caps often indicate the hydrant is located on a water main and has high pressure. White caps may indicate that it is part of the water system but not near a main.
Cast iron is the most common material used for fire hydrants, although ductile iron or stainless steel may also be used. Bronze is used in many of the parts associated with the main valve and drain valve areas. Some hydrants have automatic flushing devices that keep the water safe for consumers on the distribution system. These systems remove disinfectant byproducts.
Installing a Fire Hydrant
Installing a fire hydrant is a complex process that should only be undertaken by professionals with the right skills and knowledge. Once the right fire hydrants have been selected and orders, a professional should check them before installation to ensure that no damage has been sustained during transit. If the hydrant must be stored before installation, it should be done with the inlet face down. It should also be reinspected before installation.
Professionals working on hydrant installation must also be wary of several elements, including:
- Ensuring adherence to all local cire codes, fire authorities, and municipal design standards.
- Properly coordinating the hydrant installation with water mains for appropriate fire flows.
- Careful handling of all elements to avoid damage.
- Cleaning all foreign materials from the hydrant before installation.
- Identification of a spot that is easy to access.
- Installation of a gate valve to isolate for maintenance and emergency shut-off purposes.
- Once installed, the hydrant should be moved from fully closed to fully open and back to ensure no obstructions block the flow of water.
- The hydrant should also be hydrostatically tested. Following the test, the hydrant should be flushed and checked for damage.
Installing a fire hydrant is no simple task. It often takes weeks – if not months – of planning. This planning ensures you select the right location and design for your needs. Additionally, you often have to obtain the proper permits and adhere to any local regulations. Working with experienced professionals can make this entire process much easier. Legacy Fire has a proven track record for installing hydrants. Contact our skilled staff today to find out more about how we can help with your fire hydrant needs.