Note: Part 1 was published in the October 2007 issue of Fire Engineering.
AN ENGINE COMPANY PERFORMING A REVERSE hoselay will lay hose from the fire to a hydrant, where it will connect the apparatus with a short section of suction hose and then pressurize the hoselines with its pump. Pumping hoselines from an engine connected at a hydrant takes advantage of the hydrant’s available gallons-per-minute (gpm) flow and the pump’s capacity. This is a common way for fire departments that do not have large-diameter hose (LDH) to operate. Fire departments using LDH can also benefit by performing a reverse lay and pumping LDH at a hydrant, because it maximizes the hose’s flow capabilities. Although LDH has significantly less friction loss than smaller conventional hose, hydrant pressure alone may be insufficient to overcome the friction loss in LDH when it is flowing a large volume of water or it is in a long hoselay.
Effective deployment of hose of any diameter requires an understanding of basic water supply hydraulics. For example, pumping hoselines from an engine connected at a hydrant cannot make water. The hydrant must have the potential to flow the desired gpm. This potential or available water flow from a hydrant is calculated by noting its static pressure, as measured on the pump’s master intake gauge, with no water flowing and comparing to its residual pressure, once water is flowing. Formulas for calculating a hydrant’s available gpm flow are beyond the scope of this article. In simple terms, however, a relatively small drop in pounds per square inch (psi) from static to residual pressure indicates that the hydrant is capable of supplying more water. Conversely, a large drop in psi, as noted by a low residual pressure, indicates that the hydrant is flowing near capacity.
You cannot equate the strength or potential flow from a hydrant by considering only its static pressure. Static pressure alone can be deceiving. I have seen hydrants with extremely high static pressures that were connected to very small water mains or had valves closed in the water main grid system. Consequently, the high static pressure rapidly dropped to a dangerously low residual pressure when the hydrant was flowing.
There are, on the other hand, municipal water supply systems that operate at relatively low pressures but have massive water mains capable of delivering extremely high volumes of water. Hydrants on such a system may not have enough pressure to flow a large volume of water through a long lay of LDH. Fire departments with such a system should conduct flow tests to determine how many gpm their hydrants can flow through various lengths of their LDH. For example, one city with a relatively low-pressure/high-volume water supply system has determined through flow tests that hydrant pressure can flow 500 gpm through 400 feet of its four-inch LDH. Further, the flow is reduced to 350 gpm when the length of the four-inch LDH is increased to 700 feet. Tests such as these will determine when the demand for water or the length of the hoseline necessitates that an engine connect directly to a hydrant and pump the LDH.
Strongly consider a reverse lay at big fires, fires that have the potential to get big, or whenever high gpm or long hoselays result in friction loss that hydrant pressure alone cannot overcome. Fire departments using four-inch LDH will realize much greater flows when it is pumped at a hydrant than they would if they relied only on hydrant pressure.
As mentioned, positioning pumpers at hydrants, rather than at the fire, reduces congestion at the fire scene, allowing room to most effectively spot aerial devices and reducing apparatus exposure to falling walls or power lines.
Begin a reverse lay the same as a forward lay-by checking the hydrant for water and clearing any debris that may have been deposited in an outlet missing a cap. Often, a company preparing to reverse lay will “back down” to the fire, thus positioning the hosebed toward the fire and the apparatus toward the hydrant.
Companies that forward lay their LDH most of the time may not be accustomed to performing a reverse lay. This can result in delays by taking too much time at the fire before they lay out to a hydrant. An engine company that relies too heavily on preconnect hoselines may not be equipped with hose loads that facilitate a reverse lay or may lack proficiency in deploying them.
Hose loads that are finished in a bundle, a skid, or a series of reverse horseshoes are ideal for a reverse lay, because they can be rapidly pulled, dropped in the street, and stretched while the engine proceeds to the hydrant.
Companies should know what hose, appliances, and tools to set out at the fire when performing a reverse lay and train frequently so that they can complete the evolution without confusion or delay. The objective here is to get the pumper “led out,” connected to a hydrant, and pumping as quickly as possible.
AT THE FIRE
At the fire, a LD water thief manifold can be used to divide the supply and control the flow to handlines, master streams, sprinklers, and standpipe connections. Make sure, however, that your LDH is capable of adequately pressurizing the standpipes in your jurisdiction, because standard LD supply hose has a maximum operating pressure of 185 psi.
Two engines performing reverse lays to different hydrants provide a secondary, redundant supply of water. This enhances the safety of firefighters should one of the engines break down or a vehicle cut the supply of water from one of the LD hoselines.
Note the master stream device in photo 1. It has a five-inch storz inlet and no control valve. Flow to the device is controlled by the LD water thief. When my department acquired these devices more than 20 years ago, it seemed like a good idea, and they are if they are operated close to a pumper with a short stretch of LDH. My romance with these devices quickly faded, however, the first time we had to hand-stretch hundreds of feet of LDH on a hot summer day to operate a master stream at the rear of a warehouse.
 (1)The engine reverse lays large-diameter hose and pumps from the hydrant. |
Recently, our companies have been issued lightweight portable master stream devices (photo 2) with 2½-inch inlets and control valves. These new devices are easier to use than the older five-inch devices, because hand-stretching three-inch hose is much easier than stretching five-inch hose and the smaller device can be more easily moved once it is deployed. The only disadvantage that the smaller device has, as compared with the older, larger one, is that it doesn’t flow as much water (500 vs. 1,000 gpm). The reduced flow, however, is usually worth the increase in mobility and control.
 (2) A large-diameter water thief controls the flow to the master streams |
Relay pumping LDH from a hydrant to a quint or an engine operating at the fire necessitates the commitment of two apparatus, but it allows the use of preconnect hoselines, apparatus-mounted master streams, and aerial devices at the fire. Positioning the pump at the source of water has, in addition to the advantages already explained, another benefit: Let’s say that the quint or engine operating on the fire scene breaks down. In this event, it is entirely possible for the engine connected to the hydrant to increase its pump discharge pressure on the hoseline supplying the disabled apparatus to the point where nozzle pressures are restored. In this situation, the disabled apparatus becomes, in effect, a big manifold pressurized by the pumper at the hydrant. As I mentioned in Part 1 of this article, the limiting factor in this operation is the setting of the intake relief valves on the disabled apparatus. If they are set too low, say below 150 psi, they may open and dump water, preventing the restoration of adequate pressure.
 (3) the 2 1/2-inch handlines |
Now, let’s consider another scenario: In this case, the engine pumping at the hydrant breaks down. What happens next depends on the hydrant pressure and the demand for water. There are water supply systems capable of flowing a high volume of water at relatively high pressures. Engines relay pumping at a hydrant in such a system may often operate at idle, because hydrant pressure itself is sufficient to overcome friction loss in the LDH and maintain at least 20 psi residual pressure as read on the master intake gauge of the apparatus operating on the fire scene.
 (4) the sprinkler siamese connection . (Photos by Eric Goodman.) |
In this scenario, the loss of the engine pumping at the hydrant will have little or no effect on the operation. But what if it does? What if the engine pumping at the hydrant is needed to boost the pressure because hydrant pressure alone is insufficient? In this situation, have another engine take suction by connecting a short section of LDH to an unused steamer intake on the disabled engine. Now, transfer the LDH from the disabled pumper to a discharge on the other engine and restore pressure on the line.
Fire departments must have contingency plans for what to do when an apparatus breaks down or a water supply is lost at a critical point in an incident. As luck would have it, it is not a matter of if this could ever happen; it’s a matter of when it will happen.
MAXIMIZE GPM
An engine may not always reverse lay to the closest hydrant, because it can be too close to the fire and endanger apparatus. Also, the closest hydrant may supply insufficient water. Engine companies should be familiar with the water supply system in their jurisdiction. Knowledge of the water supply may result in an engine company’s deciding to bypass hydrants on small or “dead-end” water mains and connect to a more distant hydrant on a strong water main.
An engine pumping at a hydrant can increase its gpm flow by connecting two suction hoses to the hydrant-one from the hydrant’s large “steamer” connection and a second from a 2½-inch outlet. A company making its connection to a hydrant’s steamer outlet can connect a gate valve to one of its 2½-inch outlets and then open the hydrant. Later, a second suction line can be connected to the gate valve with the use of a 2½-inch female × storz adaptor, supplying the pumper with additional water without shutting down the hydrant.
FOUR-WAY VALVES
An engine company equipped with a four-way hydrant valve has the option of reverse laying an LDH supply line from an apparatus pumping at a fire to a hydrant but not pumping the supply line. Say an engine is given an order to supply an engine pumping from its booster tank at a fire in a junkyard, trailer park, or some other congested area. Because of the close quarters at the fire scene, the engine company chooses to back its apparatus toward the fire and reverse lay LDH from the apparatus at the fire to a hydrant. At the hydrant, the supply line is connected with a four-way valve, because the engine company officer is confident that hydrant pressure is sufficient to supply the apparatus pumping at the fire. If he is wrong or if the fire intensifies, he has the option of connecting his engine to the four-way valve and boosting pressure in the supply hoseline without interrupting the flow of water.
SPLIT HOSELAY
A split hoselay involves two pumping apparatus that combine a forward and reverse hoselay. A split hoselay can be very effective in situations where it would be difficult for an apparatus to lay a supply line to or from an engine or quint operating at a fire scene. Also, consider a split lay when the combined length of two apparatus hosebeds is necessary to reach from the fire to a hydrant.
A split lay is ideal for establishing a water supply for apparatus pumping in congested areas with limited access such as trailer parks, scrap yards, and apartment and warehouse complexes.
 Split hoselays. (5) The engine forward lays its own supply line from the street entrance into the abandoned warehouse complex. |
A split lay begins with the first-arriving engine or quint forward laying a supply line for itself from the street entrance of the congested area. Then, a second pumper connects to the end of the first company’s supply line and reverse lays back to a hydrant.
 (6) The second engine reverse lays from the first engine’s supply line to the hydrant. |
A few years ago, my company responded on mutual aid to a four-alarm fire involving a grocery store that threatened a block of commercial buildings. When we arrived, four engines had already forward laid LDH supply lines from hydrants on the same street. This was not a very efficient operation, because no engine was pumping directly from a hydrant. Our assignment was to operate a master stream from our 50-foot aerial device in a narrow, dead-end alley at the rear of the store. The conditions here were perfect for a split lay. My company dropped our five-inch LDH at the street and forward laid our supply line down the alley. A second engine connected to our line and reverse laid past two hydrants to connect and pump from a more distant hydrant fed by a strong arterial water main.
 (7) The water thief controls the flow from the second engine, at the hydrant, to the first engine, at the fire. |
There is a variation of the split lay that involves two pumping apparatus that both forward lay and connect their supply lines. Consider a long, narrow driveway leading to a large home. The first-arriving pumper drops its LDH at the street and forward lays its supply line up the driveway, where it will operate at the fire. A second engine then stops at a hydrant, checks it for water, and forward lays its LDH to the driveway entrance, where the two lines are connected.
 A variation of the split lay: (8) The engine forward lays its supply line into the warehouse complex. |
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 (9) The second engine forward lays large-diameter hose from the hydrant and |
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 (10) connects to the first engine’s supply line. |
This “forward-forward” version of a split lay is fast, but it relies on hydrant pressure to supply the engine pumping at the fire. This is a situation where a four-way hydrant valve can be very useful; if more water is needed, the second engine can return to the hydrant and boost pressure in the supply line without interrupting the flow of water.
PUMPING LDH
Modern apparatus specified for LDH should have one or more large-diameter discharges for safety. The National Fire Protection Association (NFPA) requires that large-diameter discharges be located away from the pump operator’s position. This requirement is intended to protect the engineer operating at the pump panel from a burst line or an LDH coupling that separates. As mentioned in Part 1, the NFPA requires that pump suction and discharge valves designed to flow to or from LDH must fully open or close in no less than three seconds. This requirement is intended to protect LDH and the pump from water hammer and protect firefighters from sudden, violent movement of LDH when it is charged too quickly. This requirement is for good reason. I have seen firefighters straightening out LDH at the pump get their hands caught in a kink when the line was charged too quickly; they were unable to free themselves without the help of other firefighters.
 Pumping LDH. (11) This large-diameter discharge, placed on the right side of the apparatus for safety, is plumbed with four-inch-diameter pipe to efficiently flow a high volume of water. |
For maximum efficiency, specify a large-diameter discharge with four-inch-diameter piping and a four-inch full flow valve, making it possible for some engines to flow the entire capacity of their pump through one LD discharge. Flow tests of my company’s new 1,500-gpm pumper indicated that we could efficiently pump its rated capacity through one LD discharge. Efficiency was judged by noting that the pressure read on the pump’s master pressure gauge was just a few psi higher than the reading on the gauge for the LD discharge. A small difference in gauge readings while pumping 1,500 gpm is caused by a minimal friction loss in the pump and piping to the LD discharge and in the LD discharge itself.
 (12) The LDH is pumped from the 2 1/2-inch discharge #3 (the suction on the right). The 2 1/2-inch discharge is plumbed with three-inch pipe. |
Engines without an LD discharge can also pump LDH. How to connect and pump LDH depends on the size of pipe connecting 2½-inch discharges to the pump. Say, for example, that a pumper’s 2½-inch discharges are plumbed with three-inch pipe, which is quite common. In this case, it is entirely possible to pump LDH efficiently from one 2½-inch discharge using a 2½-inch × storz adapter, especially if pumping four-inch LDH. Use a discharge directly from the pump rather than connecting to a rear discharge because of the additional friction loss in the longer length of pipe.
 (13) 150 psi on the gauge to discharge #3, pumping five-inch LDH, requires |
A pump with 2½-inch plumbing will be less efficient supplying LDH from one 2 1/2-inch discharge. Attempting to do so can require excessive engine rpm and pump-discharge pressures. If this is the case, consider pumping LDH from two 2½-inch discharges by using a 2½-inch × storz siamese. Also, it’s a good idea to connect short sections of three-inch hose (20 to 25 feet) to the siamese to minimize friction loss. You will notice in photo 15 that the sections of three-inch hose connected to the siamese supplying the five-inch LDH are extremely short-too short, actually, for this operation. That is because they are actually used as “pigtails” in standpipe operations and were improvised to conduct flow tests for this article.
 (14) a main pump discharge pressure of 190 psi because of the friction loss in the pump and piping to the 2 1/2-inch discharge. |
Flow testing is the most accurate way for a fire department to determine how each apparatus can most efficiently pump LDH. For example, lay out 200 to 300 feet of LDH to a master stream device with a 1½- to two-inch solid stream tip. Now pump the LDH at 150 psi, as read at the gauge for each discharge flowing. Record the pitot gauge pressure taken at the master stream to determine the gpm flow for each method of pumping LDH. Also record the engine rpm and reading on the master pump discharge pressure gauge for each test. Friction loss in the pump and piping to discharges may result in the master pump pressure gauge’s reading significantly higher than the 150-psi readings on the gauges for the individual 2½-inch discharge outlets. The method of pumping LDH with the highest gpm, the lowest engine rpm, and a master pump discharge pressure closest to 150 psi is the most efficient.
IS LDH RIGHT FOR YOUR DEPARTMENT?
Let’s say that a fire department presently reverse lays dual three-inch hoselines from a fire and pumps them at hydrants spaced every 300 feet. What does it expect to gain by replacing its three-inch hose with four- or five-inch LDH? I know of a fire department that used to forward lay two 3½-inch supply lines from a hydrant and rely on hydrant pressure to supply engines pumping at the fire scene. This worked well for this big city fire department, whose engine companies see a lot of fire duty. Consequently, these companies were very unhappy when five-inch LDH showed up at their doorstep.
 (15) Really short sections of three-inch hose siamesed to pump LDH from 2 1/2-inch discharges #1 and #2. |
A fire department considering the purchase of LDH should have realistic expectations of how LDH will improve its operations. Information provided by hose manufacturers and sales representatives, although accurate, is not sufficient for making an informed decision as to whether LDH is right for your fire department.
 (16) 150 psi is maintained at discharge #1. |
First, a department should conduct flow tests to compare the performance of the hose presently in use and LDH supplied by the vendor for evaluation. Then, it should conduct realistic evolutions with the loaner LDH on fire scenarios likely to occur in their jurisdiction. A comprehensive evaluation of LDH must take into account the water supply system, apparatus, staffing, and the department’s fireground operations.
 (17) 140 psi at discharge #2. |
Do not purchase LDH and then find out that your apparatus, designed for conventional hose, cannot effectively carry and deploy it. This can be a real problem with quint apparatus equipped with a rear-mount aerial device, because hose may have to pass through restrictive chutes to clear the turntable.
Flow tests and realistic evolutions are needed to make an intelligent choice between four- and five-inch hose and storz or threaded couplings. Say that your department has a strong water supply with fairly high-pressure hydrants spaced every 300 to 500 feet. Then four-inch LDH may be adequate. Also consider whether your department usually reverse lays hoselines and pumps them at a hydrant. Again, four-inch LDH is probably the best choice. Does your department encounter situations where firefighters must hand-stretch hoselines to or from a hydrant? If so, don’t buy five-inch LDH until you’ve actually tried to hand-stretch it hundreds of feet around corners and parked vehicles.
 (19) Pitot gauge readings at the master stream device determine the gpm flow for the tests. |
LDH can be specified with threaded instead of storz couplings. True, double male and double female adapters are necessary to perform both forward and reverse hoselays, but threaded couplings have some advantages over storz. First, threaded couplings are not as bulky, so they don’t take up as much room in a hosebed and are less likely to snag on obstacles. Second, threaded couplings are a lot easier to work with when spanner wrenches must be used. Finally, when deciding on the size and couplings of LDH, consider what your neighboring fire departments are using. Compatibility without the need for special adapters is definitely an advantage when a fire department operates with mutual-aid companies.
 (20) Rpm recorded for each flow test: Lowest rpm, lowest master pump pressure, and highest gpm indicate the most efficient method of pumping LDH. |
A realistic evaluation may reveal that LDH may not be all that it is advertised to be-at least as far as your department is concerned. We are well aware of the advantages of LDH, but has your department considered its disadvantages? First, it is heavy; an empty 100-foot section of five-inch LDH weighs more than 100 pounds. Picking up this hose in ice and snow can be back breaking. Second, it can be difficult and time consuming to deploy, because it is generally purchased in 100-foot sections that frequently kink on narrow and congested city streets; you must use short sections. Third, it is vulnerable to damage from vehicles and can block the street for incoming apparatus. Consider the previously mentioned department that used to lay two 3½-inch lines and now lays a single line of five-inch LDH: The 3½-inch double-jacket hose was far more durable than the LDH; it is less likely to be damaged if it is run over by a vehicle; and, most importantly; if one line bursts, there is always the second line to maintain at least a reduced water supply.
In my research for this article, I consulted with several firefighters, officers, and driver engineers, and I have concluded that there are two major mistakes fire departments make when purchasing LDH. First, they listen to hose salespeople more than their own people and purchase LDH primarily on the salesperson’s recommendations. Second, they purchase LDH because they see other departments using it. Both mistakes can result in less efficient fire operations and unhappy firefighters.
LDH has remarkable capabilities, but it is only as good as the firefighters deploying it. LDH requires frequent, hands-on training for it to be used safely and effectively. It can injure firefighters who are not skilled in handling it and can delay getting water to the fire if used improperly. A fire department will never fully realize the capabilities of LDH if it deploys it the same way at every fire.
Thanks to the following for their assistance with this article: Bill Peters, apparatus supervisor (ret.), Jersey City (NJ) Fire Department; Richard Avallone, training officer, Pompano Beach (FL) Fire Rescue; Ray Bell, captain, Miami Dade (FL) Fire Rescue; and “Mac” McGarry, engineer (ret.), Glenview (IL) Fire Department.
BILL GUSTIN, a 34-year veteran of the fire service, is a captain with Miami-Dade (FL) Fire Rescue and lead instructor in his department’s officer training program. He began his fire service career in the Chicago area and teaches fire training programs in Florida and other states. He is a marine firefighting instructor and has taught fire tactics to ship crews and firefighters in Caribbean countries. He also teaches forcible entry tactics to fire departments and SWAT teams of local and federal law enforcement agencies. Gustin is an editorial advisory board member of Fire Engineering.
