BY TOM MURRAY
As a member of the San Francisco (CA) Fire Department High-Rise Committee, I started reviewing major high-rise fires that have occurred within the United States. It became clear that significant failures of or problems associated with fire protection systems were factors in these fires and greatly compromised the fire attack, in some cases resulting in firefighters’ deaths.
Profile of the 55-story high-rise building in which the drill was conducted. (Photo by author)
The building’s fire-flow capability was one of the reasons most often cited as a problem in these incidents. The failure of these systems often necessitated that the responding fire department acquire the water needed to attack the fire by pumping into the building using standpipe systems or taking hoselines up stairways.
Realizing this, our department conducted an operational drill in a 55-story building to determine how we should modify our High-Rise Operations Plan. Our findings, presented here, may assist you in evaluating your department’s policy for conducting a high-pressure pump operation in a high-rise building 30 stories or higher, if these structures are part of your jurisdiction.
We found the following to be key areas:
- City water supply system. Pressure and volume must be sufficient to supply department pumpers so they can pump the required quantity of water into the high-rise building.
- Fire apparatus. Two-stage pumps should be available. Discharge gates should be capable of being opened at pressures above 200 psi.
- Fire supply hose. The burst pressure rating of the hose should be 50 psi over the maximum discharge pump pressure.
- Fire department fittings and appliances. They should be pressure tested to the maximum pressure that will be pumped.
- High-rise building configuration. Prepare preplans that include your department’s ability to pump to the highest floor of the highest high-rise in your city in case the building’s pumps fail.
- Fire department connections (FDC). They should be accessible and safe to operate near in relation to debris falling from the fire building. The FDCs should be labeled with the recommended pump pressure and should be marked to designate the area of the building they serve.
- Standpipe systems. The fire prevention bureau should verify that these buildings’ standpipe systems have been pressure tested to the maximum fire flow that may be needed. Be wary of piping that is not capable of handling the pressure that you will supply it with.
- Building fire pumps should be supplied by the municipal water system.
- As an added precaution, FDCs are provided so that the fire department can pump into the building’s standpipe system.
- Most buildings are plumbed so that the FDC supply goes directly to the discharge side of the building’s fire pump, thus supplying the building’s standpipe risers directly from the fire engine pump. This gives the fire department control over the pressure and volume being pumped into the standpipe risers.
High-pressure hydrant with pressure-reducing valves.
An important exception to this is that some buildings have the FDC supply plumbed to the suction side of the building’s fire pump. In these buildings, the fire department would be augmenting the existing water supply to the building’s fire pumps from the municipal water system. NFPA 20, The Standard for the Installation of Centrifugal Fire Pumps, does not allow the FDC piping to be tied in on the suction side of the fire pump.
The significance of this design is that the fire department is not in control of the pressure and volume being pumped to the standpipe risers. The reason is that this design has a pressure relief on the building’s fire pump. This pressure relief prevents the fire department from pumping too much pressure into the FDC suction side of the building’s fire pump. Without such a pressure relief, the building’s pump would be damaged. The impact of this is that should the building’s pump not work, then the fire department would be limited to the pressure set on the pump’s pressure relief.
In the building we used for the drill, this pressure relief valve was designed to open at 125 psi.
Should this 55-story building have a fire and the building’s fire pumps be off line for whatever reason, the San Francisco Fire Department would be able to pump a maximum of 125 psi into this building’s FDC.
In this drill, the pressure relief did open, to relieve the excess pressure the department’s engines were pumping into the FDC. The pump room drains could not keep pace with the pressure relief discharge; had this fact not been discovered, the building’s pump room would have been flooded. The power generators for the entire building’s emergency life safety systems were located in this pump room. This building is currently being retrofitted to correct this problem. The question is, How many high-rise buildings currently have this type of FDC connection to the building’s fire pumps?
Feedback from other fire service agencies relative to their operation plans for pumping into high-rise buildings indicates that they rely too heavily on the building’s fire protection systems to provide the required fire flow during a working fire.
Keep in mind that high-rise fire protection systems are subject to the following conditions.
- They are built to the building and fire codes at the time of construction.
- Some can be poorly maintained and supervised.
- They are subject to vandalism, sabotage, and terrorism.
- Massive power outages could affect the building’s fire pumps and other life-safety systems.
- They may be affected by another fire protection system’s going off line during a fire.
- During a fire, the fire and fire flow water runoff could damage critical portions of the building and equipment, resulting in the loss of electrical power and flooding of the basement, where the building’s fire pumps and backup power generators are often located.
SAN FRANCISCO’S WATER SYSTEM
- Engines. To counter the threat of fire, the city of San Francisco has 42 engine company units. All have Detroit Diesel series 60, 12.7 liter, six-cylinder, 450-horsepower engines with Allison automatic transmissions. All fire pumps are 1,500-gpm rated two-stage pumps. All engine pump discharge outlets are three inch. There are two three-inch auxiliary gated inlets with two main suction inlets that have a screw-type, three-inch inlet that widens to a six-inch manifold into the pump.
- Low-pressure municipal hydrants. San Francisco has more than 7,000 low-pressure municipal hydrants. Three are at each intersection in the downtown high-value districts; one or more are located between blocks. In the closely built-up residential districts, two hydrants are at intersections; there is one in less hazardous areas.
Pressures in the downtown high-value district can range from an average of 80 to 125 psi from 10- to 12-inch mains. In outlying residential areas, the expected average pressure is from 45 to 100 psi from six- to 12-inch mains. All low-pressure hydrants have two individually gated three-inch NST male outlets.
- Auxiliary high-pressure system. In addition to the low-pressure hydrant supplies, the San Francisco Fire Department owns and operates its own water distribution system, called the “auxiliary high-pressure system,” which has three pressure zones. The 750,000-gallon Jones Street Tank, at 369 feet elevation, feeds the lower zone. The 500,000-gallon Ashbury Tank, at 494 feet elevation, serves the middle zone. The 10.500 million-gallon Twin Peaks Reservoir, at 758 feet elevation, serves the upper zone.
Pressure in the Jones Street zone can average from 120 to 140 psi. With Ashbury pressure added, the Jones Street zone would be approximately 200 psi. When Twin Peaks is added to the Jones Street zone, the pressure can be increased to 300 psi average.
San Francisco Fire Department procedure requires that whenever a high-pressure hydrant is to be used, a 97-pound brass, pressure-reducing valve (Gleason Valve) must be placed on the 31/2-inch male NST high-pressure hydrant outlet to keep discharge pressure at a manageable level (see photo 2).
There are approximately 600 high-rise buildings in San Francisco. For the purpose of this drill, a 55-story building with 778 feet of elevation was used. This building has 52 tenant occupied floors. It is 240 feet wide and 140 feet deep and has a gross building area of 1.844 million square feet. Square footage for the occupant floor ranges from 30,000 on floors 2 to 42 and 28,000 for floors 43 to 52. The upper penthouse level is 3,000 square feet.
Individual floor height from floor to plate is 14 feet. Mechanical floors 15 and 37 are 28 feet high.
The building’s daytime population is 5,000 to 6,000 people; the average for nights and weekends is 300 to 500 people. A concourse restaurant has a seating capacity of 40. A restaurant on the 52nd floor seats 500.
Eighteen floors are not sprinklered: the Plaza level; the Mezzanine level; floors 6, 7, 8, 9, 10, 12, 13, 14, 32, 36, 37 (the mechanical floor), 42, 48, and 49; and the lower and upper penthouse floors.
The building’s FDC is set up with the majority of and the most important FDCs on the building’s south wall facing the sidewalk.
The building’s design did not offer protection from overhead debris falling in the area of the FDC. This is an important safety consideration for firefighters working in the area of the FDC and for protecting FDC supply hose connections from being cut by falling debris. It was proposed that aerial ladders be extended over these FDC connections to offer some cover.
Four three-inch FDC connections are plumbed to the concourse and basement garage levels B-1, B-2, B-3, and B-4. These FDCs serve only the south side of the concourse level and the belowground-level parking and mechanical floors: two FDCs to the sprinklers on the south side of the building’s belowgrade area and two inlets to the dry standpipe outlets on the south side of the building below grade. The additional inlets on the Pine Street side of the building are the only combination FDC above-grade inlets for the entire building: six inlets to the combination low-rise portion, floors 2 to 27, and six inlets to the combination high-rise portion, floors 28 to 55.
Combination inlets on Pine Street. There is no protection from falling debris in the area.
On the north building exposure, there are four inlets that serve only the north side of the below-grade area and two inlets each for the sprinkler and dry standpipe systems.
When preparing for a high-pressure operation, there are several important considerations regarding your fire apparatus.
- The master pressure gauge should be able to read pressures up to a minimum of 600 psi.
- Two-stage pumps are recommended because single-stage pumps do not operate as efficiently at pressures over 350 psi. The Fire Department of New York (FDNY) uses a three-stage pump for high-rise pumping operations.
- The suction relief valve discharge needs to be capped to prevent it from discharging when pumping in tandem (short relay pumping or pumping in series, as it is known in some departments).
- The pump operator needs to keep the discharge relief valve closed or set high, depending on the brand of pump, so that the pump can generate pressure sufficient for the operation. Unless your pump’s discharge gate valves are rated for discharge pressures of 200 psi or higher, inlet and discharge gates need to be in the opened position prior to pressurization, or the high pressures will lock them closed.
- Leave bleeder (gate drain valves) valves open to ensure a constant flow of water to keep the pump cool when excessive static pumping takes place, or the pump will quickly heat up.
- Keep the tank-to-pump valve closed to protect the tank from overpressurization. Also, keep the tank fill valve closed in case the pump-to-tank clapper leaks water.
SAFETY HIGHEST PRIORITY
Safety considerations must always be the highest priority. High-pressure pump operations expose personnel to dangers from ruptured hoselines, fittings, appliances, and standpipe risers.
- Verify and document that the system piping in the building is capable of handling the expected high pressures.
- Designate a high-pressure pump operation supervisor and a separate safety officer who is knowledgeable about pump operations.
- All personnel must wear safety equipment. All unnecessary personnel should be at least 50 feet away from the fire apparatus pump FDC hose connections.
- Close off the area around the fire apparatus discharge gates and supply hose leads to the FDC with caution tape.
- Because of the potential danger to the pump operator, do not use discharge outlets off the pump panel.
- The fire hose is the most vulnerable piece of equipment in a high-pressure operation. Do not exceed the annual service test hose pressures. Hose manufacturers recommend that discharge pressures be 50 psi below the rated burst pressure. Los Angeles City and New York City fire departments use a 2,000-psi burst pressure rated hose for high-rise pump operations.
- Lash discharge hose together one foot from the coupling at discharge and inlet connections. This will ensure that the loose hose will be held in place should the hose break loose from its coupling connections.
- Use threaded couplings, not quick-connect or quarter-turn storz couplings, because the couplings may come undone at high pressures.
- Use multiple smaller-diameter hose (21/2- or three-inch), not large-diameter hose (LDH). A ruptured LDH hose length is extremely dangerous and would also mean shutting down the entire operation. The City of Richmond (CA) Fire Department connects siamese appliances to FDC combination inlets so that multiple supply lines feed each FDC inlet.
- Set wheel chocks in front and at the rear of driver-side rear duals.
- Spanner tighten all connections and fittings. The safety officer must monitor this.
- Should discharges need to be shut down, throttle down the pump pressure first. At such high pressures, ruptures in hose and damage to pumps and water mains are significant realities.
- Unless the standpipe system has been tested at the pressure you intend to pump into it, keep personnel out of the stairwell serving that standpipe riser.
- Monitor standpipe risers for leaks. The most vulnerable points on standpipe risers are at fitting connections.
ADVANCED PUMP OPERATIONS: LESSON PLAN
Topic: High-Rise Building High-Pressure Pumping.
Time: 45 minutes.
Conditions: Demonstrate skill.
Behavior: The student will be able to describe and physically set up a pumping scenario as described within this lesson plan.
Standard: With a minimum 100-percent accuracy according to the information contained in the lesson plan.
Reference: New York City and Los Angeles City Fire Department Procedures.
Materials needed: Fire engines (2), fire hydrant, fire hose (high-pressure and ordinary), related fittings, spanners, utility rope, webbing, traffic cones, caution tape,
Preparation: It is critical that fire departments that respond to high-rise life safety buildings be able to pump satisfactory fire flows at pressures that can effectively supply fire attack nozzles should the building’s fire pumps be off line or damaged. This evolution must be performed with strict attention to safety during all aspects of the drill evolution.
The goal in this lesson plan is to set up two engines so that they are pumping in tandem (short pumper-to-pumper relay) to overcome pressure loss caused by elevation.
This procedure can produce higher pressures that normally would not be possible with a single pumper while maintaining discharge volume. With two-stage pumps, this will create an effective four-stage pumping machine.
I. Engine A takes hydrant supply.
- In downtown San Francisco, this supply would be from four supply leads off a high-pressure hydrant.
- Hydrant supply from a Jones Street high-pressure hydrant would be 140 psi.
- The higher the hydrant pressure, the easier it is on the pumps.
- If a high-pressure hydrant is not available, take the supply from two low-pressure hydrants. LDH could be used from domestic low-pressure hydrants to the first pumper in tandem.
II. Engine A takes hydrant supply into the two main suction inlets and two auxiliary gated inlets.
- Transfer valve in volume position.
- Suction discharge relief valve capped, to take a suction supply higher than that for which the relief valve is set.
- Discharge relief valve set high or closed so that higher pressures can be achieved.
- Tank-to-pump valve closed so tank does not rupture.
- Tank fill. Recirculating valve closed so tank is not pressurized.
- Face apparatus pump panel side away from the building for pump operator safety.
- Discharge hose off officer’s side and rear outlets only, for personnel safety.
- Make sure all hose connections are spanner tight.
- Lash all hose at connections so that they hold should a hose separate or burst.
- Set wheel chocks front and back of driver-side rear duals.
III. Engine B takes supply from Engine A.
- Transfer valve in pressure position.
- Suction relief valve capped.
- Discharge relief valve set high or closed.
- Tank-to-pump valve closed.
- Tank fill. Recirculating valve closed.
- Face apparatus pump panel side away from the building.
- Four incoming supplies: two main inlets and two auxiliary inlets.
- Four discharge lines off Engine B into the building FDC: two off officer side, two off rear.
- Lash all supply and discharge hose together or to an anchor point.
- Set wheel chocks front and back of driver-side rear duals.
IV. FDC connections. It is recommended that the discharge hose off Engine B into the building’s FDC be marked with a felt pen at the hose coupling connection. A separation of 1/8-inch is acceptable when the hose is pressurized. More than this would indicate the hose and coupling may separate. Circle the entire hose at the coupling with the marking pen, as close as possible to the coupling so that any pulling away from the coupling will be noticed.
Inlets supply hoselines, which are lashed and marked with gate numbers.
After pressure is removed from the hose, this 1/8-inch separation should retract into the coupling. If it does not, check the hose for possible pressure damage.
Put the outlet number of the engine’s discharge gate supplying that hose on the hose at the FDC connection. This will identify the gate to be closed if a hose connection to the FDC fails.
V. Prepare to charge lines. When both engines and hydrant supply are set up, prepare to charge all lines with hydrant pressure. At this time, open the inlets and outlets in use. The reason for doing this is that, if they have ball-type valves, they will be difficult or impossible to open under high pressure.
Check all coupling connections for leaks, and make them spanner tight. Also, remove all kinks. Kinks restrict water supply and also can cause the hose to rupture at the kink site.
VI. Pumping to the high-rise building’s FDC. Standpipe risers are required to flow 500 gpm to the highest point of the building; subsequent riser outlets should flow 250 gpm.
You must know-not guess-at what pressure to pump into the high-rise building FDC. You can apply several methods:
- FDC labeled with required pressure. Some jurisdictions require this. Be aware that this may only be the minimum pressure called for in the fire code. Hose friction loss on the fire floor and your department’s nozzle discharge pressure may not have been figured into the labeled pressure figure.
- Building prefire plan. Fire personnel could view the discharge gauge of the building’s fire pump while the pump is running. This would show the required pump pressure to the highest point of the standpipe risers.
- Check the water supplies category of the building’s required prefire plan. It should indicate the pump pressure required for the highest point of the building.
- Calculate required pump pressure using the proper hydraulic formula: The height of the building 2 .433 ` standpipe friction loss of .055 vertical height for four-inch-diameter risers or .008 for six-inch-diameter risers. Factor in FDC, hose friction loss, and desired nozzle pressure. The building used for our operational drill was 778 feet tall, with six-inch risers (778 feet 2 .433 4 336.87) ` (778 2 .008 4 6.224) ` fog nozzle pressure of 100 psi ` friction loss of 25 psi for FDC, and 22 psi for a 100-foot 13/4-inch hose pack for 490 psi required pump pressure. A solid-stream nozzle pressure of 50 psi and a friction loss of 21/2-inch hose will greatly reduce this number.
- Estimate required pump pressure if none of the above are available or feasible. Calculate the pressure by multiplying the number of floors by 5 and then adding a constant of 150 psi. The constant is derived by adding the average pressure required at the roof outlet (125) and the friction loss in the standpipe outlet (25 psi). (Compliments of the Los Angeles Fire Department High-Rise Fire Pump Procedure.) This is a good solution. It provides for friction loss at standpipe (25 psi), hose friction loss, and a nozzle pressure of 100 psi, rounded to 150 psi.
- Realize the following things at this point. It may be difficult to visually check the number of floors involved. Also, it is common practice to describe floors in terms of the tenants who occupy the floors, not actual floors. High-rise building floors are generally 14 feet high, not 10 feet like most residential building floor heights. Mechanical floors are also generally double the height of normal tenant floors, being 28 feet or more.
- Pump the required pressure to the maximum height of the building. This is done to open check valves that might be in place in the standpipe risers. Pumping just to the fire floor may not do this. Example: In the 55-story building used for this drill, the high-pressure standpipe risers split at the 28th floor. Fire is on the 30th floor. Developing a pump pressure just to the 30th floor may not open the check valves because of the head pressure that must be overcome because of the additional 25 floors (406 feet).
- Pump pressure must be increased and reduced slowly to avoid placing water-hammer pressure surges on hose, fittings, mains, and the standpipe system.
- Open floor outlet valves slowly to avoid pressure surges at the nozzle. The standpipe discharge outlet valve is the only sure control of pressure at the nozzle. Staff and open nozzles prior to opening the standpipe outlet valve. Otherwise, extreme static pressures could make it impossible to open bales of solid or fog nozzle ball-type valves. Split-ball nozzle valve shutoffs are recommended.
VII. Anticipated Problems-Difficulties
- Hose: Not suitable for the pump pressure required.
- Fittings: Not pressure tested to the pump pressure required.
- Running the pump at high rpms without water discharge (Pump ` Heat 4 Damage). It’s hard to know at the pump panel when discharge lines are actually open and flowing from the nozzles. Long delays in putting lines to work can cause extended static pumping.
- Inattention to details: Being casual about the pump evolution.
- Standpipe systems not properly maintained: Pressure tested to withstand the required pump pressure into the FDC.
a. FDC Inlet Connections
- Clearly label all: dry, combination, or sprinkler inlet. Identify the building location served by each inlet.
- The building’s prefire plan should identify whether the FDC supplies the suction side of the building or the discharge side of the fire pump.
- Stamp on the FDC inlet plate the pump pressure required to supply the highest point served by that FDC.
b. Fire Hose
Two engines pumping in tandem.
Equip selected high-rise district response engines with high-pressure-capable hose. New York and Los Angeles use a 2,000-psi rated hose. The City of Richmond, California, uses extruded aluminum, not pyrolite, for hose couplings-for strength reasons.
Use dedicated fittings for high-pressure pumping. Richmond has moved from brass fittings to chrome-plated steel fittings.
Test for high-pressure use. Be sure bales can open at pressures over 100 psi. The split-ball shutoff is recommended; this design assists in opening and closing the bale with the hydraulics of the water pressure.
- Recommend solid-stream nozzles that can be effective with a high- and low-volume water supply.
- Recommend 21/2-inch hose for interior fire attack with a solid stream nozzle with a 11/8-inch minimum tip size.
- Recommend a portable pressure gauge for connection to the standpipe outlet so the fire attack team will know exactly what the discharge pressure is at the standpipe outlet. The standpipe outlet valve can be adjusted according to the attack team’s
TOM MURRAY, a 30-year veteran of the fire service, is captain of Engine 39 at the San Francisco (CA) Fire Department. He is an adjunct faculty member at the Santa Rosa Junior College Fire Technology Program; an instructor with the Department of Emergency Services, County of Sonoma; and a contract instructor with the Industrial Emergency Council of San Carlos, California, teaching driver training/pump operations, fire command, fire management, and incident command system.