Quickly controlling and extinguishing serious fires is the most effective life-saving action that the fire department can perform. Safe and effective fire fighting requires water—sometimes large amounts of water—and in many communities, water is provided by fire hydrants.
In this article, I will identify some of the many conditions that restrict the effective use of fire hydrants, explain the techniques for properly testing and flushing fire hydrants, check common water supply hose practices, and provide plenty of tips and suggestions to help engine companies in the following situations Ensure reliable water supply for various operating conditions. (For an excellent review of fire hydrant nomenclature, design features, and applicable standards, please see “Fire Hydrants” in Paul Nussbickel’s Fire Engineering, January 1989, pages 41-46.)
Before proceeding, three points are worth mentioning. First of all, throughout the article, I refer to the firefighters responsible for driving the engine (pump) equipment and operating the pump as “engine company drivers” or simply “drivers”. In many departments, this person is called “engineer” or “pump operator”, but in almost all cases, these terms are synonymous. Secondly, when discussing the correct techniques for testing, flushing and connecting the fire hydrant, I will send this information directly to the driver, as this is usually his responsibility. However, in some departments, supply lines were laid from remote fire hydrants into the fire, leaving one member to perform the connection and charging when ordered. To avoid injury and ensure uninterrupted water supply, this person must follow the same testing and flushing procedures as the driver. Third, suburbs are no longer affected by urban crime and vandalism, and few communities will not face budget deficits that affect basic services. Problems that have long affected the availability of fire hydrants in inner city work are now everywhere.
The effectiveness of fire hydrants as a source of water supply can be divided into three categories:
The water pipes of the water hydrants are limited in size and aging, resulting in a decrease in available water and static pressure; and
Although my purpose is to study the first and third types of problems, I must emphasize the importance of the second type of problems. Understanding the water pipe size and/or flow test data is an important part of pre-accident planning and efficient operation of the engine company. (See “Fire Flow Testing” by Glenn P. Corbett, Fire Engineering, December 1991, page 70.) It must be determined that the fire hydrants supplied by the main pipe with a diameter of less than 6 inches and the fire hydrants with a flow rate of less than 500 gpm should be determined to prevent Difficulty in operation and insufficient fire flow occurred. In addition, attention should be paid to the location of fire hydrants with the following special characteristics: they are located on dead-end mains, require special accessories, contain only 212-inch nozzles, and they cannot use drains because they are located in floodplains or areas with high groundwater levels.
Listed below are some of the most common problems caused by improper inspection and maintenance, unauthorized use, and vandalism:
The inoperable operating rod or operating nut is severely damaged so that the fire hydrant wrench cannot be used;
In many communities, the local water department regularly inspects and maintains fire hydrants. This does not exempt the fire department from inspecting itself to ensure the normal operation of the fire hydrant. Engine company personnel should periodically check the fire hydrant in their response area by removing the cap from the largest nozzle (traditionally called the “steam connector”) and thoroughly flushing the barrel to remove debris. Perform such tests during alarm response, drills, and other outdoor activities to make it a habit. Pay special attention to fire hydrants that lack a cover; fragments may have been placed in the barrel. Flush the newly installed fire hydrants thoroughly to prevent rocks trapped in the main pipe and riser from damaging the pump and equipment.
The following are some key points about the safety methods for testing and flushing fire hydrants. First, on the fire hydrant with the lid firmly in place, be sure to check to make sure the fire hydrant is closed before attempting to remove the lid. Second, remove the cap from the largest nozzle on the fire hydrant and flush through the opening to best ensure that all entrained debris is removed. Third, it may be necessary to tighten other covers to prevent leakage or, more importantly, to prevent the cover from being blown away violently when the fire hydrant is opened. Fourth, always stand behind the fire hydrant when flushing. Obviously, standing in front or next to you is very likely to get wet; but the most important reason for standing behind a fire hydrant is that the rocks and bottles trapped in the fire hydrant barrel or riser will be forced under considerable pressure Through the nozzle, it becomes a dangerous projectile. In addition, as mentioned above, the cover may blow off, causing injury.
Another important point relates to the degree to which the operating valve must be opened to effectively flush the fire hydrant. I observed that the driver opened the fire hydrant several times, allowing water to flow through the uncapped nozzle under tremendous pressure. This high pressure may push aluminum cans, glass and plastic bottles, cellophane candy wrappers, and other debris above the level of the nozzle and prevent them from being flushed out of the barrel. Then the driver closed the fire hydrant, connected the suction pipe, opened the fire hydrant again, and filled the water pump. Suddenly—usually like the first handle entering the fire zone—water will run off as unwashed debris enters the suction line. The attack line became limp, causing the nozzle staff to quickly change direction; when the intake pressure dropped to zero, the driver immediately panicked. The correct flushing technique involves opening the fire hydrant a few times, waiting a few moments, and then closing the fire hydrant until the discharged water fills about half of the nozzle opening (see the illustration on page 64).
The vandalism itself may partially or completely disable fire hydrants. I often encounter fire hydrants with missing caps, missing threads (most commonly on 212-inch nozzles), missing valve caps or bolts at detachable flanges, operating nuts worn out due to unauthorized use, they are only better than pencils The diameter is slightly larger, the hood is cracked, the barrel freezes due to unauthorized use in winter, the fire hydrant is deliberately tipped over, and sometimes even completely lost.
Measures taken to combat vandalism. In New York City, four main types of vandalism devices are installed on fire hydrants. Each of these devices requires a special wrench or tool to operate, which further complicates the driver’s work. In many cases, there are two devices on the same fire hydrant-one device is used to prevent the cover from being removed, and the second device is used to protect the operating nut from unauthorized use. In most communities, the only tools needed to put a fire hydrant into service are a fire hydrant wrench and one or two adapters (national standard threaded to Storz adapters, ball valves or gate valves, and four-way fire hydrant valves are the most common). But in downtown areas, where vandalism is rampant and fire hydrant maintenance is questionable, many other tools may be needed. My engine company in the Bronx carries 14 types—yes, 14 different wrenches, covers, plugs, adapters, and other tools, just to get water from the fire hydrant. This does not include the various sizes and types of suction and supply hoses required for the actual connection.
Generally, a single engine company operating independently or two or more engine companies operating in coordination establishes water supply from a fire hydrant. A single engine company can use one of two common hose laying methods-straight pipe or forward laying and reverse laying-to establish water supply from fire hydrants.
In straight or forward laying (sometimes called “hydrant to fire” laying or “tandem” supply laying), the engine equipment is parked at the fire hydrant in front of the fire building. One member walked down and removed enough hoses to “lock” the fire hydrant, while removing the necessary wrenches and accessories. Once the “fire hydrant” personnel give a signal, the engine driver will go to the fire building with the function of the water supply hose. The members remaining in the fire hydrant then flush the fire hydrant, connect the hose, and charge the supply line according to the driver’s order. This method is popular because it allows the engine equipment to be placed close to the fire building and allows the use of pre-connected handles and deck pipes. However, it has several disadvantages.
The first disadvantage is that one member stays at the fire hydrant, reducing the number of people in the fire building to put the first handle into use. The second disadvantage is that if the distance between the fire hydrants exceeds 500 feet, the friction loss of the water supply hose will greatly reduce the amount of water reaching the pump. Many departments believe that dual 212-inch or 3-inch lines can allow the right amount of water to flow; but usually, only a small part of the available water is used effectively. Large diameter hose [(LDH) 312 inches and larger] can make better use of fire hydrants; but it also brings some of the problems discussed in the following two paragraphs.
Another disadvantage of the forward layout is that the engine equipment is close to the fire building, and the elevator equipment may not reach the best position. This is especially true for the second-maturity ladder company, which usually reacts in the opposite direction to the first-maturity engine. The narrow streets magnify the problem. If the engine equipment itself does not prove to be an obstacle, then the supply hose lying on the street is most likely. The charged LDH will cause huge obstacles to the subsequent Ladder Company equipment.
Uncharged LDH can also cause problems. Recently, a fire broke out in a row of shops in Long Island, New York, and a tower ladder tried to drive over a dry 5-inch rope laid by the engine that expired first. A coupling caught on the edge of a crack in a rear wheel, breaking the firefighter’s leg at the fire hydrant, rendering the supply line unusable. An additional note about ladder equipment and supply lines: make sure that the torturer and outrigger are not inadvertently lowered onto the hose, thus making a fairly effective hose clamp.
In the opposite or “fire-to-water” case, the engine equipment is first parked in the fire building. If members find a fire that requires the use of handles, they will remove enough hoses with nozzles for deployment in and around the fire building. In multi-storey buildings, it is vital to remove enough hoses to reach the fire scene without “shortening”. According to the signal from the nozzle worker, official or other designated member, the driver goes to the next fire hydrant, tests it, flushes it, and connects the water supply hose. If a member encounters a serious fire, they may “put down” the second handle in the fire building for use by another engine company or lay large-diameter pipelines to supply incoming ladder pipes or tower ladders. The New York City (NY) Fire Department almost exclusively uses reverse laying (referred to as “post-stretching” for short).
The advantages of reverse laying include leaving the front and sides of the fire building open to place the ladder company equipment; efficient use of personnel because the driver can perform the fire hydrant connection separately; better use of the available water supply because the engine is at the fire hydrant.
One disadvantage of the reverse arrangement is that any mainstream equipment based on equipment is removed from the tactical arsenal unless the fire hydrant happens to be close to the fire building. Another disadvantage is that there may be a long handle laying and the need for high pump discharge pressure, which can be overcome by “filling” any 134 or 2 inch pipeline with a 212 inch hose to reduce friction loss. This method also allows the option to disconnect the 134-inch or 2-inch hose and use a larger handle when conditions deteriorate and require use. Connecting a gated star or “water thief” device to a 212 inch hose provides greater flexibility. In FDNY, a maximum of six lengths (300 feet) of 134-inch hoses are allowed to keep the pump discharge pressure (PDP) within a safe and reasonable range. Many companies only carry four lengths, further reducing the required PDP.
Another disadvantage of reverse laying is that it usually cannot use pre-connected handrails. Although this is true, and the pre-connection does allow rapid deployment of hand lines, the fire department has over-relied on them, and nowadays few firefighters can accurately estimate the extent of hand lines. The biggest problem with pre-connected lines may be the “one size fits all” approach. When the pipeline is not long enough, this may cause a significant delay in watering the fire. Unless preparations are made in advance to extend the pre-connected pipeline-this is usually achieved through the use of gated stars and manifolds-the fire can quickly get out of control.
On the other hand, sometimes the pre-connected line is too long. In a recent fire, the first engine was located in front of the fire building, and only about 100 feet of hose was needed to reach the fire site and effectively cover the single-family home. Unfortunately, the two pre-connected pipelines carried out in the cross-laid hose bed were both 200 feet in length. Excessive kinking caused a large amount of water loss, enough to force the nozzle team out of the fire.
Perhaps the best way is to equip each engine equipment with a hose load, allowing straight and reverse laying. This approach permits a high degree of tactical flexibility when selecting a hydrant and positioning the apparatus.
Until about the 1950s, many engine companies were “two-piece” companies, consisting of a hose car equipped with hoses, fittings, and nozzles, and an engine equipped with pumps and suction ports. The hose cart will be located close to the fire building to facilitate shortening the length of the pull cord and afford the cost of using its “car tube”. The engine will supply water from the fire hydrant to the carriage. Even today, triple pumps are almost universally used, and many fire department water supply procedures require that the first engine be installed near the fire building, unless the fire hydrant is nearby, the second engine is connected to a fire hydrant and supplies the first one.
The main advantage of using two engine companies to build the water supply system is to place the first engine near the fire building for rapid deployment of pre-connected handles. Since many fire departments have the lowest level of staffing, the length of the hand line must be as short as possible. In addition, due to the long response distance, many fire attack operations are started with booster tank water until the second due engine arrives to establish positive water supply.
The advantage of this method over straight or forward laying is that when the hydrant spacing exceeds 500 feet, the second engine can deliver water to the first engine and overcome any friction loss limitations in the supply line. The use of large-caliber hoses further improves the efficiency of water supply operations. When the altitude of the fire fighting building is higher than the fire hydrant and the static pressure is weak, this method will also prove to be advantageous in very hilly areas. Other situations that may require the cooperation of two engine companies to establish water supply are as follows:
The actual procedures used by the two engine companies to set up the water supply system will depend on street conditions, the need for ladder companies to enter the fire building, and the response direction of each engine. The following options are available:
The second-use engine can pick up the supply line that has been locked to the fire hydrant by the first-use engine, connect and charge; the second expired engine can pass through the first one and be placed in the fire hydrant; the second one The expired engine can be returned to the first engine on the street and placed in a fire hydrant; or if time and distance permit, the supply line can be stretched by hand.
The biggest disadvantage of using two engine companies to establish a continuous water supply from a single source is that it is equivalent to putting all the water supplied eggs in one basket. In the event of mechanical failure, blockage of the suction line or failure of the fire hydrant, there will be no water supply redundancy as individual engine companies fix their own fire hydrants. My suggestion is that if the third engine is usually not assigned to a structural fire alarm, please request it as soon as possible. The third engine should be located at another fire hydrant near the fire building, and be prepared to quickly deploy handles or provide emergency supply lines as needed.
No matter what type of water supply procedure is usually used, as long as the fire hydrant is located near the fire building, it should be considered. This usually eliminates the need for a second engine to power the first engine and frees up time for the second engine to find its own fire hydrant, thereby providing water supply redundancy. It is important that before using your own fire hydrant, the second expiring engine should make sure that the first expiring fire hydrant has a “good” fire hydrant and will not run aground without continuous water supply. Communication between engine company officials and/or drivers is essential.
The fire hydrant chosen by the preferred engine company should be as close as possible to the fire building, but not too close, so as not to put the driver and the drilling rig in danger. For advanced fires on arrival, the use of deck pipes can prove beneficial; however, the potential size of the collapsed area and radiant heat issues must be considered. Other hazards include heavy smoke and falling glass, which can cause serious injuries and cut hoses.
In many fires, there is no danger of collapse and radiant heat. Therefore, the only consideration when choosing a fire hydrant is the number of hoses required to reach the fire and the need for the elevator equipment to enter the fire building smoothly. When the streets are narrow or crowded with parked cars, the positioning of the engine company may pose a challenge. How can the engine driver keep his equipment away from approaching the ladder equipment and still help to place the handle quickly and efficiently in the fire?
The answer to this question involves two related considerations-the specific pump suction port to be used and the length and type of suction connection (hose) available. Many modern engines are equipped with gated front suction. A piece of “soft casing” is usually pre-connected for immediate use. (Some suction devices are equipped with rear suction-instead of front suction or additional suction.) Although pre-connecting the suction hose is not a problem, the tendency to always use front suction due to its convenience may be. On narrow streets, the use of front suction usually requires the engine driver to insert his equipment “nose” into the fire hydrant, blocking the street and damaging the equipment that arrives later. The shorter the cross-section of the soft suction hose, the greater the problem. Unless the engine is in an ideal position, short lengths of soft suction hoses also have kinks, which are rarely possible.
The driver must be prepared to use any suction port on his device according to the size of the possible positioning options. Pumps rated at 1,000 gpm and higher have large (main) suction ports and gated inlets of 212 or 3 inches on each side. Side suction is effective because they allow the engine equipment to be parked in parallel next to the fire hydrant, keeping the street clear. If a semi-rigid suction connection is used instead of soft suction, kinking will not be a problem. If you do not have a semi-rigid suction hose, consider wrapping a soft suction hose around the back of the fire hydrant to reduce kinks. The soft suction hose must be long enough to allow this. Another consideration when using side suction is that the side suction port is not gated. At least two times when I tried to open the front suction gate valve, when I turned the control wheel on the pump panel, the threaded rod between the gate and the control wheel became loose, making the front suction unusable. Fortunately, this situation has never happened in critical situations.
Don’t neglect gated entrances; they can be very valuable when snowdrifts, cars, and trash block fire hydrants, preventing the use of soft or semi-rigid suction connections. In these cases, a 50-foot-long “flying wire” can be carried, consisting of a hose of 3 inches or larger, to help reach the fire hydrant.
When pressure issues arise, as often happens in large fires, multiple alarm engine companies should connect a piece of hard suction hose to the fire hydrant to eliminate the risk of soft or semi-rigid suction hose collapsing.
In addition to using steam connectors, consider connecting a ball valve or gate valve to a 212-inch fire hydrant nozzle. You can then connect the water supply hose to the gated entrance to provide additional capacity, which may come in handy in the event of a fire in vacant buildings, connected or closely spaced wooden buildings, and large areas of “taxpayers”.
In high-value areas where hydrants are closely spaced, one engine may be connected to two hydrants. Some cities still maintain a high-pressure water supply system, which may allow two engines to share a fire hydrant.
In winter, consider covering all exposed suction hose joints with aluminum foil to prevent snow and icing, which may clog the hose or prevent female swivel joints from rotating freely.
A senior driver of FDNY Engine Company 48 coined the term “two minutes of terror” when describing the first two-minute experience of the first engine driver at the site of a structural fire. Within two minutes (or less), the driver must place the engine equipment near the fire hydrant, scramble to test and flush the fire hydrant, connect the suction hose, inject water into the pump, and connect the handle to the discharge door (or make sure to The connected hose bed is removed from the hose), and the pump is engaged. Hope that all these tasks are completed before the police officer calls water. As a driver, one nickname you never want is “Sahara”.
If this is not enough responsibility, then the two minutes described above is even more terrifying in the inner city, because there are four important questions to find answers:
3. If the fire hydrant is upright and fixed, will water flow during the test, or will it break or freeze?
4. If the fire hydrant is working properly, can the cover be removed within a reasonable time to connect the suction hose?
In order to better understand the difficulties encountered by fire hydrants in high-damage areas and why these four issues are so important, consider the following three events.
The driver of a busy South Bronx Engine Company reacted first due to a fire in the work apartment. After stopping in front of the fire building to allow the handle to be extended, he continued to find the fire hydrant along the block. The first “fire hydrant” he found was not actually a fire hydrant, but just a lower bucket protruding from the ground-the fire hydrant itself was completely gone! As he continued searching, the next fire hydrant he found was lying on its side. Finally, he saw an upright fire hydrant, almost a block and a half from the fire building; fortunately, it proved to be operational. Others in his company complained for several days about how long they had to drain and repack the hose, but the driver did his job and ensured continuous water supply when faced with extreme difficulties.
When a senior driver from the northeast of the Bronx arrived, he noticed a serious fire on the first floor front window of an inhabited private house. There is a fire hydrant on the sidewalk nearby, which seems to be fast and easy to connect. But appearance can be deceptive. The driver put the wrench on the operating nut and opened it with a lever, and the entire fire hydrant fell to one side! But before heading to the next fire hydrant, he notified his officials via a portable radio that there would be a delay in the water supply (and notified the engine company that was due for the second time, just in case it needed help).
In addition to communicating any delays or other issues, when the water in the pressurized tank is supplied with a hand strap, the officials or the nozzle team must be made aware of this fact. Once hydrant water is available, this information must also be communicated to officials and the nozzle team so that they can change their strategy accordingly. There is another point: good drivers always maintain a complete booster tank during operation, as a safety measure, in case the fire hydrant lacks water.
I will provide a personal example to illustrate the difficulties often encountered when trying to remove the large cover from the fire hydrant steamer connection. Since the anti-vandal device and the cover are stuck or frozen in place, our company’s drivers often use a sledgehammer to hit each cover, using several violent blows. Hitting the cap in this way will scatter the debris trapped in the threads, and the cap can usually be easily removed. A few months ago, I was assigned to open an engine company in Upper Manhattan. At about 5:30 in the morning, due to a fire in a multi-family house, which later proved to be a fatal fire, we were dispatched first. Out of habit, I placed the 8-pound maul at the beginning of the tour in a familiar location on the rig, in case I need it. Sure enough, the lid on the fire hydrant I chose required several knocks to remove the lid with a wrench. If multiple blows with a sledgehammer (or the back of the axe, if there is no sledgehammer) do not loosen the cover sufficiently to allow removal, you can slide a section of pipe through the handle of the fire hydrant wrench to gain greater leverage. I don’t recommend I have seen the wrench bend and crack by tapping on the handle of the wrench itself.
The effective use of fire hydrants requires foresight, training and quick thinking at the fire scene. Engine equipment should be equipped to respond to various water supply emergencies, and drivers should be equipped with portable radios to improve fire communication. There are many excellent textbooks on engine company operations and water supply procedures; please consult them for more information on the hoses discussed in this article and other related topics.
Post time: Dec-01-2021
