DISCUSSION OF METHODS FOR RESTORING FROZEN FIRE HYDRANTS TO SERVICE
While There Are Many Methods for Thawing Frozen Hydrants, Not All Will do the Work in the Short Time Required
THE man within his well heated home has paid his fire insurance premium, and of course has paid his city taxes. Therefore, he feels that he has done everything possible to safeguard himself in the event of fire. Part of his taxes make possible the fire protection service provided by the Water Department and the Fire Department, and the insurance is some compensation for losses that may result, if fire does occur.
Outside his home there is a hydrant. It is one of the many that stick out like hitching posts in the residential part of the city. Not every home has a hydrant in front of it. because with the aid of hose lines and department pumpers, it is possible for one hydrant to safeguard a large group of houses.
However, if anything should happen to a hydrant that would put it out of service, the man within the well heated home, and those residing in the neighboring houses are deprived of a major fire-fighting defense which they believe the city is providing without interruption.
To insure continuous hydrant service through the winter months, it is the practice for the Water Department or the Fire Department, or sometimes a ioint crew from both, to make inspections in the fall. When the inspections are made, the stuffing boxes are examined. and particularly the drip valves through which the water in the barrel drains out after the hydrant is used. If a hydrant barrel is free from water, the chief cause for a frozen hydrant is removed.
However, it is not possible to keep all hydrant barrels dry. Some hydrants are set in low, moist ground, and water seeps into the barrel. For such installations, the drip ports are closed.
But in spite all precautions, hydrants will freeze. Perhaps some thoughtless Street Department employee used the hydrant, or children, not realizing the seriousness of the prank, turned the operating nut.
When a frozen hydrant is found, it must be restored to service as rapidly as nossible. Time is a very important factor, for no one can foretell which hydrant will he operated within the next few hours. Each should be considered the most important part of the fire protection system of the city, and since each hydrant protects a group of houses rather than one, the fire protection danger that follows when a hydrant is out of service, is greatly increased.
There are several ways to thaw a hydrant. Rock salt has been used with good, but very slow results. The salt is emptied into the barrel of the hydrant, and as salt lowers the freezing point, the ice is melted. This method is not to be recommended where time is an important factor.
Electricity Not Suitable
One hears so much about electricity as a thawing medium that the inexperienced fireman is apt to give this system first consideration. He reasons that since it has proven so effective in thawing frozen services, it must also be efficient for thawing hydrants.
But he forgets that a service has a comparatively small cross sectional area. A hydrant may be considered equal to a six-inch main. Therefore, while high amperage electricity has been effective in thawing a frozen service, it is a different matter when the transformer or generator is connected to a six-inch main. Since time is so important a factor, one must remember that possibly three hours may be required to thaw a hydrant electrically.
The basic rural method of thawing, that is the hot water kettle, is also used. With this plan, a tube is inserted into the hydrant barrel and hot water poured down the tube into the barrel. The hot water melts the ice and makes it possible to operate the hydrant. But one must have a good supply of hot water on hand, and lots of it. Hot water can hold a limited amount of heat, and this heat is soon given up to the ice in the hydrant.
There are several units now on the market which utilize steam for quick thawing. By means of good design the size and weight of the devices have been held down, so that truly, they are portable units. Primarily, they consist of a heating element and a steam boiler. For fuel, acetylene or some other quick heating substance may he used. The heater is used to convert the water in the boiler into steam. Unlike hot water, which can hold only so much heat and no more, steam can be charged with a large number of thermal units, dependitig on the dryness of the steam and the amount of superheat. Therefore, with a lesser amount of water, it is possible to conduct a greater amount of heat to the frozen section.
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Restoring Frozen Hydrants to Service
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Depending on the type of steam thawing unit used, six or more hydrants may be thawed with one charge of fuel and water. Unless a hydrant is frozen solid, it may be thawed in a few minutes.
As a safeguard, the boilers are provided with a pressure relief valve, so that steam will “blow off” when a predetermined pressure is reached. This is important, for the valve protects both the equipment and the men who operate it.
These steam thawing units have been so effective for frozen hydrants that a number are now being used by the New York Fire Department.
In deciding on the system of thawing to be used by a Fire Department, the officer must answer the question:
“Is it effective, and how fast does it operate.”
Remember, fire will not wait! It will go crackling up the walls, while the gang of firemen at the corner are cussing at the hydrant that refuses to he thawed.