Virtually all textbooks and training programs on apparatus or tactics discuss supporting fixed fire suppression systems with fire apparatus. This article will explore and review some special circumstances at industrial facilities that warrant pre-planning.
The summer 2013 edition of Industrial Fire World discussed the use of an Aircraft Rescue and Firefighting (ARFF) vehicle that was used to successfully supply three percent AFFF to a semi-fixed foam system protecting a jet fuel tank farm. This was during a system commissioning test. Although the ARFF vehicle was not designed for this; it was made to do so by applying extensive preplanning and creativity in vehicle operation. This was a complex operation that requires regular refresher training. As we discussed then, a purpose-built industrial foam pumper is idealized for this task. The department has since acquired one. Because it is purpose-built, elaborate bypass procedures are not needed to supply semi-fixed foam systems. An additional benefit is that it can also be used for high volume pumping at more conventional structure fires. Municipal departments that own industrial foam pumper or have mutual aid access to one should take advantage of these “super-pumper1 ” type capabilities.
Foam systems added to conventional structural pumpers are often intended for vehicle fires or the application of Class A foam to small structures or outdoor fires. The flow rates and duration provided by these systems tends to be limited to these smaller fires. They can be used to advantage at industrial fires but their limitations must be clearly understood.
In-line eductors, for example, have a maximum hose length on the outlet of the educator, commonly 300 feet with 1¾-inch hose. That may seem like a lot, but it is not when circumnavigating the interior flammable liquids use area at a large industrial building. Series in-line eductors2 , sometimes called jet ratio controllers or “double suckers” can move foam a long distance, but they are typically used only for master stream appliances. They are also relatively complicated to set up.
Around-the-pump proportioners do not have limits on the length of hose (other than imposed by the pump itself) but they do have limits on intake pressure. Depending on the brand, intake pressures are typically limited to 5-to-50 psi. Most industrial sites will have much higher pressure and control of intake pressure must be understood. One way NOT to control the intake pressure is to throttle back the hydrant itself. Doing so will cause the hydrant drains to be open and erode the ground under the hydrant.
Positive pressure foam injection systems overcome both of these limits but are less common and also tend to be supplied by small (30-50 gallon) foam cells.
Another example of using apparatus as key protection is supplying semi-fixed water spray systems as shown in Figure 1. Such a system is simply a matter of economics. The fire apparatus provides the needed pressure rather than installing a fixed fire pump which could be prohibitively expensive for a single hazard. Such systems provide several advantages over using master stream appliances for protection. Water spray systems provide uniform water cooling. Master streams tend to deliver more water than needed in some areas and leave dry spots in others. The connection can be at a safe standoff distance. The disadvantage is that such a connection can get lost among the process piping. Further, some part of this system pipe might be exposed to the fire or damaged by an explosion.
The most complicated semi-fixed system seen by this author was undoubtedly an attempt to be economical and take advantage of the on-site industrial foam apparatus to protect a chemical process structure. The system had two separate inlets, one for foam solution and one for foam concentrate as shown in Figure 2.
The foam concentrate line fed a ratio-controller in the deluge sprinkler system protecting the lower levels of the structure.
The foam solution line fed a manual semi-fixed system at the roof level. The two systems were designed to work together to protect the process structure. The foam solution line would be supplied like any other foam solution line from an industrial pumper. The foam solution line cannot be fed by eductor because the flow and outlet pressure requirements do not match standard eductor ratings. A proper match would be very difficult to properly engineer. Although around-the-pump proportioners could properly deliver foam solution, they have pumper inlet pressure restrictions. The facility’s initial water pressure would be close to 150 psi, well above what any around-the-pump proportioner could manage. It is possible to feed hydrant water into the industrial pumper’s water tank and then feed the around -the-pump proportioner from the tank. This introduces the need to constantly prevent overflow. Overflow could create unanticipated loads on the facility drainage system. The drainage system is needed to prevent the spread of flammable liquids and carry off design fire fighting water flow runoff.
Less common and not well understood by the site’s fire brigade was the need to supply foam concentrate to the ratio controllers in the deluge risers protecting the lower part of the structure. This was intended to be done via the pumper’s on-board foam transfer pump. Although the vehicle is capable of this function, regular training is needed to ensure that everyone understands the way the system was designed.
Fire apparatus support is often incorporated into industrial fire suppression system design. It is vital that the fire service understand their role in supporting these systems. This article reviews a few of many potential applications that industrial responders may face.
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John Frank is Senior Vice President of the XL Catlin’s Property Risk Engineering / GAPS Loss Prevention Center of Excellence, where he is involved in loss prevention research and loss prevention training. XL Catlin’s Property Risk Engineering / GAPS team provides property loss prevention consulting and delivers individually tailored solutions to protect and enhance property, production, and profit. With approximately 220 engineers and consultants in 18 countries, the team brings clients occupancy specific experience as well as deep knowledge of specific hazards across industries. The XL Catlin insurance companies offer property, casualty, professional, financial lines and specialty insurance products globally. Businesses that are moving the world forward choose XL Catlin as their partner. To learn more, visit xlcatlin.com.
1 The FDNY developed the super-pumper concept and the tactics to go with it in the 1960’s. The most powerful industrial pumpers are approaching the capacity of the original super pumper; which could pump 10,000 gpm @ 150 psi. Containerized pump modules now come very close to this capacity. The original super-pumper was limited by 4½-inch hose. Industry now has hose up to 12-inch in diameter available. 2 Series means that one educator feeds another in series, analogous to relay pumping.
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