The dry hydrants, aka the standpipe, are commonly used by firefighters as the main water supply in rural areas where the municipal water system is a luxury and can’t be easily accessible. Typically, an unpressured, permanently installed pipe, the dry hydrant is well below the water level of a lake or pond at one end, usually with a strainer to prevent debris or foreign objects from entering the pipe.
The other end of the pipe, however, is located on the surface of the ground with a hard sleeve connector on it. A pumper fire engine drafts water from the lake or pond, when needed, with a primer by vacuuming the air out of the dry hydrant as well as the hard sleeve and fire engine pump.
With the pump intake at lower pressure, the lake water is partially forced into the above-ground dry hydrant, and all the way into the pump through the hard sleeve, due to atmospheric pressure on the water along with its own weight. Now the water is available when pumped by the engine’s centrifugal pump.
Installed close to developed water supplies, a dry hydrant can be found in most areas without ready water accessibility which may be rural or not within easy reach of the public water system.
In case of a fire, local dry hydrants play a critical role of providing adequate water in an effective and convenient way to fight the fire. These hydrants, utilizing a non-pressurized pipe system, are installed for good and connected to nearby lakes, ponds, streams, or even reservoirs in these areas. Exempt from standard hydrant testing, they need less maintenance and are more cost-effective than other types of hydrant.
Now we’d like to provide interesting insights into how these non-pressurized hydrants operate.
A dry hydrant is by appearance highly identifiable as a permanently installed aboveground pipe located close to any form of water source. What can’t be seen is the other end of the pipe buried underground connecting with the water source through a strainer that prevents the pipe from getting clogged up by debris.
In this case, firefighters need to use an adapter while pumping lake water with a fire engine’s pump by vacuuming the air out of the dry crank. By doing so, lower pressure will be created in the pump intake that forces enough water into the aboveground hydrant and then into the pumper.
The way how a dry hydrant operates can be easily understood if you know the function of its two main parts — a curve pipe and a strainer. Dry hydrants can provide water supply to areas where standard hydrants are not accessible.
What’s the difference between a wet and dry barrel hydrant?
Wet barrel hydrants are different from dry barrel ones in terms of styles and applications. Literally “wet” and “dry” mean whether the barrel of the above ground hydrant holds water or not after use.
Dry Barrel Hydrants
Water in the barrel of this type of hydrant is drained away or pumped out when not in use. Its shut-off valve is located below the surface of the ground. Because the aboveground hydrant is dry after use, it won’t be frozen during cold weather.
Wet Barrel Hydrants
In contrast to dry barrel hydrants, the wet barrel hydrant, with aboveground shut-off valves, holds no water in the barrel when not in use. With the valve of each outlet operating independently, this type of hydrant has an advantage over its dry barrel counterpart due to easy access to the aboveground mechanical parts for maintenance and adjustments, which of course turns out to be more economical.
Despite all the advantages, the Achilles’ heel of the wet barrel hydrants is freezing, and that’s why they are installed in areas with warm climates.
What is the Difference Between a Wet Barrel and Dry Barrel Hydrant?
Geographically speaking, dry barrel hydrants are commonly used in the cold regions because their underground valves ensure that no water will be left above ground, thus preventing themselves from freezing or breaking.
On the other hand, wet barrel hydrants, always filled with water from top to bottom, are frequently seen in the warm regions. In Arizona, for example, both types of hydrants are installed, but the wet barrel hydrants outnumber the dry ones.
Therefore, what is required is a customized maintenance program to keep this type of hydrant in good condition because the routine maintenance of a wet barrel hydrant is different from that of a dry barrel hydrant.
Can MAFCO’s valves be installed on wet and dry riser hydrants?
Our valves are compatible with hydrants that are designed to handle water.
