When you drive around a typical city in British Columbia, you see them everywhere: red fire hydrants on every corner, solidly connected to the municipal water mains.
The sight of a cast iron hydrant is so common, in fact, that most people take it for granted and forget it exists until a fire needs to be extinguished.
If you’ve ever spared a thought to typical fire hydrants in your city, perhaps you’ve also wondered how they came to be.
Meet Mr. Holly
Some inventors’ contributions are recognized immediately; Thomas Edison is an example. Others—like Mr. Birdsill Holly—are hardly household names, even though their contributions are nearly as prolific.
In point of fact, Mr. Holly and Mr. Edison were friends. Holly was especially talented in engineering, and became a partner at a hydraulic engines company in 1845. His first patented invention was a rotary water pump.
It didn’t take very long for others to notice Holly’s designs. Eventually, he patented an “improved fire hydrant” that delivered water with steady pressure from water mains below. Of course, the fact that he improved on previous systems also tells us that his was not the first attempt at a fire hydrant.
In the early days of municipal water works, hydrants were really more like a typical on/off spigot. When someone yelled “Fire!” everyone gathered with buckets in hand to form a bucket brigade and attack the fire the old-fashioned way.
And as far as the underground systems were concerned, long before the spigot model there were wooden water mains. When the volunteer brigade showed up during a fire, they’d remove cobblestones above the main, bore a hole or ‘plug’ in the wood, then water would flow out through the hole. This is where the term ‘fire plug’ originated.
After some of the worst fires in history occurred (for example, the 1666 fires of London that destroyed most of the city), engineers created above-ground plugs so it would be quicker to dig up the plug during subsequent fires.
Cast Iron Systems
Eventually, iron foundries began to flourish, and engineers eagerly made improvements to existing water systems by casting branched fittings to attach to the mains. Even then, however, the water was not pressurized, so fighting fires was still a rather crude operation.
In the early 19th century, a Philadelphia, Pennsylvania engineer named Frederick Graff fashioned an above-ground stand pipe that would be ready for immediate use when a fire occurred. It used a spring valve above a main valve and had a nozzle about two feet above the ground.
During the winter months, these stand pipes were covered by iron or wooden boxes that could be removed to allow valve access. By mid-century, though, most fire hydrants began to resemble the cast iron hydrants we use today.
For this, we can thank inventors like Birdsill Holly and Frederick Graff—among others.
Modern Hydrants: How They Work
Perhaps you’ve been in the area when municipal water workers are flushing a fire hydrant. They do this for several reasons:
To check for leaks in the system
For testing purposes (water colour, turbidity, flow speed, pressure, etc.)
To flush out rust and corrosion
To ensure proper valve operation
All this is critical to the working of the city water system, but it doesn’t explain the basics of how a hydrant works.
To start with, when you see a typical fire hydrant, you’ll notice a pentagon-shaped nut on top. The unusual shape requires a specialized wrench, which is a good way to keep unauthorized users from opening the hydrant.
By turning the operating nut, the hydrant main valve opens. This valve is well below ground to protect it from freezing during frigid winter temperatures. This also protects the hydrant from spraying water in the event of vehicular impact.
There are really two kinds of fire hydrants: dry barrel and wet barrel. Unpressurized hydrants are the dry barrel type. This is common for regions that have cold winters, as the upper section never contains water that would freeze and damage the entire hydrant. Instead, as the hydrant is opened, the hydrants main valve assembly allows water into the base and up into the hydrant body. Hoses attached to the hydrant body will deliver water to the fire truck, where the pumps further boost the pressure for firefighting capabilities.
Why Hydrants Matter
As mentioned earlier, most people tend to take fire hydrants for granted. We assume that we will always be protected in a fire emergency. However, if we didn’t have modern hydrants, designed for strength and durability in any weather condition, that protection simply wouldn’t exist.
Knowing more about the origins of fire hydrants helps us appreciate modern technology, and the engineers and first responders who have our safety in mind.
So, the next time you see that friendly red fire ‘plug’ on a nearby street corner, thank the engineers, the cast iron foundry workers, and—most of all—your neighbourhood’s first responders who make your life safer.