October 15, 2012

How a Fire Hydrant Works

October is Fire Prevention Month.  Learn why fire hydrants are so important to fire protection here.

There are nearly 10,000 fire hydrants in the Des Moines Water Works distribution system, and while fire hydrants are a familiar sight, the business end of the hydrant is something that many people will never see.

Like an iceberg, there is actually more of a fire hydrant below the ground than there is above the ground.  That is because fire hydrants must connect to the water main and the water must be controlled far enough below ground to ensure that water in the piping will not freeze.  If water freezes inside a fire hydrant during the winter months, the ice will block the flow of water rendering the hydrant unusable in an emergency situation.

A fire hydrant is basically a pipe with threaded fire hose nozzles at the top (above ground), and a water control valve at the bottom (six feet below ground).  Fire fighters use a special wrench to open the hydrant’s water control valve which allows water to flow up the “pipe” (the barrel of the hydrant) and out the nozzles.  When the hydrant is shut off, any water left in the barrel drains out through specially designed drain openings which only open when the hydrant is not in use.

Bonus: Do you know why the tops or “bonnets” of fire hydrants are painted different colors? Learn here.

Posted by: Ted Corrigan No Comments
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