01162017Mon
Last updateMon, 16 Jan 2017 4pm

i

Is Your Favorite a 2016 Top 10 Article?

Is Your Favorite a 2016 Top 10 Article?

Since VALVEMagazine.com was inaugurated ...

Portable Alloy Verification Devices

Portable Alloy Verification Devices

Q: What are the differences between the ...

Force and Direction Controls for Valve Actuators

Force and Direction Controls for Valve Actuators

Valve actuators deliver either linear or...

The Weekly Report

New Products

  • ja-news-2
  • ja-news-3

Industry Headlines

PA Town Approves $6B Shell Ethane Cracker Plant

Monday, 16 January 2017  |  Chris Guy

Potter Township in western Pennsylvania has granted a conditional use permit for a $6 billion petrochemical plant to be built by Shell Chemicals. The ...

Readmore

Loading...

Industry Headlines

David Paradis Named President of Weir Flow Control Division

3 DAYS AGO

The Weir Group PLC has appointed David Paradis to its group executive as president of the Weir Flow Control Division. He will take up this new role on January 23, 2017. Paradis succeeds John Heasley who was appointed Weir Group CFO in October 2016.

Paradis is currently president of Weir Oil & Gas&r...

Readmore

GE, Transocean Announce Performance-Based Service Agreement

5 DAYS AGO

GE Oil & Gas has secured a new contractual service agreement (CSA), valued at approximately $180 million, with Transocean. Under the agreement , GE will provide condition-based monitoring and maintenance services for pressure control equipment on seven of Transocean’s rigs over the next 10 t...

Readmore

PA Town Approves $6B Shell Ethane Cracker Plant

4 HOURS AGO

Potter Township in western Pennsylvania has granted a conditional use permit for a $6 billion petrochemical plant to be built by Shell Chemicals. The location was chosen because more than 70% of North American polyethylene customers are within a 700-mile radius of Pittsburgh, PA. More state and fede...

Readmore

$4.17B Canadian Trans Mountain Pipeline Expansion Approved

4 DAYS AGO

Kinder Morgan’s Trans Mountain Expansion Project has received its environmental certificate from British Columbia, Canada. The proposed $4.17 billion Trans Mountain Expansion Project would increase the capacity of the pipeline to 890,000 barrels per day. The current capacity of the pipeline is 3...

Readmore

Texas Economy Poised to Shift into ‘Second Gear’ in 2017

5 HOURS AGO

Texas job growth should increase slightly from 1.6% in 2016 to about 2% in 2017, says Federal Reserve Bank of Dallas assistant vice president and senior economist Keith Phillips.

“Job growth picked up in the second half of 2016 due to a stabilization of the energy sector,” Phillips said. ...

Readmore

World Bank: U.S. Could Boost Global Economy in 2017

4 DAYS AGO

Global growth for 2017 is projected at 2.7%, 0.1% lower than the June 2016 forecast, and 0.4% higher than the estimate for 2016. Going forward, according to the World Bank, global growth is projected to pick up modestly, reaching 2.9% by 2018.

Downside risks to global growth include increasing policy u...

Readmore

The Ubiquitous Fire Hydrant

“Form follows function” is a principle typically associated with the appearance of things that serve their purpose effectively without wasted embellishment. Once the function of such an item is determined, its shape then merely shrouds working parts and provides containment.

 

This principle is evident in the appearance of the modern fire hydrant. Virtually every aspect of a fire hydrant has a direct part to play in moving water from a buried main to its application on the surface. It’s easy to see why the fire hydrant evolved into a specialized valve resembling a pipe sticking out of the ground.


A Hole in the Ground

In the 17th century, water for fighting fire usually came from a barrel located near a building’s entrance and was thrown by hand onto the fire. This was only effective in putting out the initial flames. In time, pumps were developed that threw water farther and higher, but their effectiveness was still limited by the water source. Water mains, if they existed at all, were made of bored-out logs. To access the water meant digging a pit in the street down to the main. Then a hole was bored into the main allowing water to fill the pit to supply the pumps and the lines of bucket brigades. Once the fire was out, the hole in the main was plugged and the pit filled and marked for future use. This is why fire hydrants are sometimes called “fire plugs”

This method had obvious drawbacks. Precious time was lost finding the main, digging and drilling a hole. Debris from the hole tended to foul the pumps. By the early nineteen century when cast iron began to replace wooden mains, it became common to lay out the cast-iron water system with fire plugs at designated locations. These were cast-iron risers extending from the main to the surface through which the plug, already installed in the main, could be extracted to fill a portable canvas cistern.

Eventually, the plug was replaced by a valve to better control the water, but it was still at the bottom of a riser. Fire crews carried a long standpipe with hose connections they would attach to the valve to bring water to the surface. Once the fire was out, the standpipe was removed and the riser covered, leaving the “fire plug” flush with the ground surface, but little to mark the spot for future use.


From a Hole to a Post

Historic records cite the Philadelphia Water System as the origin of the fire hydrant as we know it in the United States. A post-style hydrant, designed by Philadelphia’s water superintendent in 1803, used a conical main valve made of leather with a brass seat placed on top of the water main. The main valve was connected by a long stem to a handle on top of the hydrant barrel that stood about two feet above the ground surface. Threads under the handle moved the stem and valve up or down when the handle was turned. A separate rod down the outside of the hydrant’s barrel and connected to the handle, also moved to control a small drain opening located below the frost line on the side of the barrel just above the main valve. It opened when the main valve was closed allowing water drainage to prevent freezing in winter. Hydrants of this type are called “dry barrel” because water is only in the upper part of the hydrant above the frost line during use.

One of the more challenging aspects of recording the history of fire hydrant design is the variety of designs that existed, especially from the middle of the 19th century. The variety stems in part from the great pride towns had in their water systems. Hydrants, perhaps the single most visible feature of a system, became objects of that pride and were cast with elaborate surface decorations. Like Philadelphia, almost every water system had its unique hydrant design custom made by a local foundry.


Americans Favor Philly Design

At the time, both European-style “flush hydrants” and Philadelphia-style “post hydrants” were in use. It was also a time when several volunteer fire brigades might arrive at a fire at about the same time, vying for control of the available hydrants. It was pride, once again, that seemed to favor the post style winning out in America. According to an 1865 article, “In the hurly-burly of a fire-alarm...a fireman looks more picturesque seated on the hydrant which he has secured for his ‘machine,’ and can maintain his position better against the next comers, than over a flush case, without such salient points; besides this, it [the post-style hydrant]...certainly looks better in the engraving of his certificate or elaborate art adornments of his engine and fire house.”1

It wasn’t just exterior decoration that set the early hydrants apart. Several ways were used to control water, including gate and compression main valves, and a “knuckle” arrangement .

Most of today’s hydrants share the basic design concept of the 1803 Philadelphia design. The compression-style valve, now made of rubber, closes in the direction of water flow. Water pressure tends to force the valve into tighter contact with its seat, making it easier to achieve a reliable seal. Modern main valves are made to be removable through the top of the hydrant if repairs are needed.

The stem terminates at the top of modern hydrants with an operating nut instead of a handle. The operating nut is usually in the shape of a pentagon to make it difficult to be engaged by common tools and prevent unauthorized operation of the hydrant. A square shape is also common.

Typically there are two or three threaded nozzles in the top of the hydrant for connecting hoses. The type and specification for the threads can vary; however, National Standard Hose Coupling Thread is now the most common standard used. The larger nozzle, called the pumper, is for connecting the fire pumper truck. It provides the primary supply of water to fight fires. The smaller nozzles are for connecting hoses for street flushing and other utility purposes. For fire fighting, hoses are not normally connected directly to hydrants as water main pressure is insufficient to extinguish most building fires. Until recent years, nozzles were sealed in place on the hydrant barrel with lead packing, making it difficult to replace a damaged nozzle. On newer hydrants, they are threaded in for easier repair in the field.

  • Latest Post

  • Popular

  • Links

  • Events

Advertisement

Looking for a career in the Valve Industry?

ValveCareers Horiz

To learn more, watch the videos below or visit ValveCareers.com a special initiative of the Valve Manufacturers Association