PURPOSE

In the event of a helicopter accident and fire at a rooftop heliport, NFPA 418 Standard for Heliports recommends low expansion AFFF  (Aqueous Film Forming Foam) be applied to the helideck from either 1) a Hose Line at the rate of 89 GPM for a duration of 2 minutes, or 2) fixed or oscillating nozzles aimed at the helideck, at the rate of .10 GPM per square foot for a duration of 5 minutes.

A hose line – if operated by a trained person - has the advantage of close in application of foam onto a helicopter fire, even if a crash occurs off the helideck. The disadvantage is the prohibitive cost of having a trained person/fire fighter at the heliport for every landing and takeoff.  Fixed or oscillating nozzles have the advantage of being activated by anyone by simply pushing turning a switch; trained/professional fire fighters need not be present.  The disadvantage is that if the helicopter crashes off the helideck, fixed nozzles cannot be aimed away from the helideck. An oscillating nozzle, however, due to its oscillating mechanism - not only sweeps foam across the helideck automatically, fully meeting the code - but also it can be aimed manually onto a fire anywhere on the rooftop, even by an untrained person due to its safe distance from the helideck.

The Model 3000 provides AFFF from an oscillating monitor/nozzle capable of being aimed manually.

PRINCIPLE OF OPERATION
Because NFPA 14 recommends buildings have a Class III wet standpipe at the roof (500 GPM at 65 psi minimum), heliport foam fire protection can utilize that water supply, as does the Model 3000. While there are many methods of proportioning AFFF foam concentrate with water to generate foam, most result in either 1) a water pressure drop [eductor method] or 2) do not permit additional rapid refilling of the unit [bladder tank method]. The Model 3000 utilizes a small electric pump to meter AFFF concentrate into the water stream supplying the oscillating monitor with no water pressure drop. The 30 gallon tank provides 2-3 times the minimum amount of foam recommended by NFPA, depending upon size of heliport. Nevertheless, the Model 3000 also has storage inside the cabinet for two additional five gallon containers of AFFF concentrate, or for storage of rescue equipment. A significant feature of the Model 3000 is that foam concentrate can be added while the unit is operating.

OPERATION
To operate, one need only turn a single switch labeled “Heliport Fire Suppression”, located in the lobby serving the heliport (where people must wait during landings) or located in a remote, supervised area such as a security office. This switch opens a butterfly valve in the building’s standpipe so that water is sent to the oscillating monitor/nozzle. The Model 3000 injects AFFF concentrate into the water stream for fully proportioned foam as it is dispensed through the oscillating monitor onto the helideck. The oscillating mechanism is powered by the same water supplying it, for simplicity and reliability.

With the monitor a safe distance from the helideck and bolted down, anyone desiring to aim the monitor directly on the fire for more rapid extinguishing can simply pull a quick release pin at the base of the oscillating monitor which disengages the oscillating mechanism. A handle provides for aiming the monitor’s nozzle in any direction with one hand

INSIDE VS. OUTSIDE LOCATION
Unlike other manufacturers’ units which have no cabinet - requiring equipment to be located in a room often far from the heliport, or having to construct a special room or weathertight cabinet - the Model 3000 features a weathertight, insulated and heated cabinet of brushed stainless steel - permitting it to be installed outside near the heliport for accessbility, if space does not permit inside the elevator vestibule.

AFFF CONCENTRATIONS
AFFF is sold in 1%, 3%, and 6% concentrated solutions. A common misconception is that 6% is more concentrated than 3%, and 3% is more concentrated than 1%. Actually, the reverse is correct. One gallon of 1% AFFF concentrate mixed with 99 gallons of plain water produces 100 gallons of properly proportioned foam. Three gallons of 3% AFFF concentrate mixed with 97 gallons of plain water produces 100 gallons of properly proportioned foam, etc. After proportioned with water, all three foams are of equal quality. 1% concentrate costs more per gallon than 3%, and 3% costs more than 6%. The advantage of 1% concentrate is that storage and pumping requirements are one third those of 3%, just as 3% requirements are half those of 6%. The Model 3000 is intended for use with 1% AFFF concentrate only. The standard 30 gallon tank provides 3000 gallons of properly proportioned, high quality, foam. Nevertheless, storage is available inside the cabinet for additional foam concentrate.