Low Expansion Foam System Description

Low expansion foam has an expansion of up to 20:1.
The advantage of low expansion foam compared to the other type of foam is the greater throw range and superior cooling effect, heat resistance and burn back resistance achieved by the higher water content. This characteristic make difficult to build up great depth of foam and can cause severe water damage in warehouse etc.
The most common systems to disburse the low expansion foam include the foam branch pipe and the foam nozzle.

• Low expansion foam branch pipe and fixed foam maker
Foam solution is sprayed through the nozzle and foam is produced in the tube as air is drawing in. The nominal operating pressure is (75 – 100 psi), a minimum operating pressure of (45 psi) is recommended. Foam concentrate is usually proportioned to the nozzle using the matching foam educator type SE-ES.

• Low-Expansion Nozzles.
Low-expansion nozzles develop expansion ratios up to 20:1. Low-expansion nozzles produce wet or fluid foam that is most effectively used for exposure protection, direct attack, and overhaul.

• Low-Expansion Foam Systems.
Low-expansion foam systems provide vapor suppression with foam blankets that are applied directly to flammable liquids. To be effective, coverage needs to be complete. The quantity of foam needed is calculated according to the total surface area of the area to be protected.

Also the monitor can used to supply low expansion foam when a large volume of foam is required.

Applications

The Sabo Española low expansion foam branch pipe or nozzle can be used with all low expansion foam agent such as Class A foam concentrate, AFFF and AFFF-AR, fluoroprotein foam concentrate. This unit can be used in a variety of flammable liquid hazard area using Class B foam concentrate.

The low expansion branch pipe is typically used by fire brigade, or for hand line application around tank farms, loading racks, aircraft hangars, and chemical plant.

The low expansion foam nozzle or foam maker is used for coverage of bounded areas or to protect floating roof, flammable liquid storage tank. Especially the tank protection can be executed with two different type of fixed system using fixed foam maker or foam chamber.

The fixed foam maker are used when the tank is an open-top construction type with either double-deck or pontoon-type floating roof. This type of construction eliminates the need for a vapor seal allowing the use of foam makers rather than foam chambers.
Floating roof foam makers are used with various types of proportioning systems such a bladder tanks, balanced pressure pump proportioning systems, or line proportioners.

• Marine Applications
• Machinery spaces
• Petroleum and Chemical Tankers
• Pump pit areas
• Dike protection
• Ground sweep nozzles for track loading rack • Deluge type foam system
• Engine room
• Cargo areas

Installation requeriments

Low-expansion foam systems shall employ AFFF, protein, or fluoroprotein foam-liquid concentrates and shall be designed for local application.

Where protein or fluoroprotein based concentrates are used, the minimum application density shall be 6.5 L/min*m2 (0.16 gpm*sq ft) of foam solution of floor area. Where AFFF concentrate is used, the minimum application density shall be 4.1 L/min/m2 (0.10 gpm/sq ft) of foam solution of floor area.

The application rate for low expansion foam shall be calculated considering the nominal application rates multiplied for the correction factor for the class of foam concentrate, correction factor for the kind of object and correction factor for height of the nozzle in case of overhead deluge system. In case of foam high destructive fuels the correction factor shall be higher and shall be determined by independently witnessed test. Fixed system application rates assume shorter pre-burn times before effective foam application.

The low expansion foam can have significantly different fire suppression and exposure protection capabilities, depending on their expansion ratio and drain time. It is important to be able to identify the type of foam that is produced based on its appearance and to understand which type of foam is needed for a given fire situation. Class A foams for example are generally wet, fluid, or dry, as follows:

a) Wet foams. Wet foam can range from a foam solution that has an expansion ratio of 1 and a drain time of 0 seconds to a watery mass of large and small bubbles that can have an expansion ratio of up to 5 and a 25 percent drain time of less than 30 seconds. Wet foam can be used for direct and indirect fire attack. Wet foam is well suited for quickly penetrating and wetting fuels, making it an ideal mop-up (overhaul) tool.

b) Fluid foams. Fluid foams have an appearance that is similar to watery shaving cream with smaller and more uniform bubbles than wet foam. Expansion ratios are typically in the range of 6 to 10, with 25 percent drain times that are typically less than 90 seconds. Fluid foams can be used for direct and indirect fire attack and for mop-up (overhaul) where blanketing is desired. They also can be used to coat horizontal and vertical fuel surfaces to provide cooling for suppression.

c) Dry or stiff foams. Dry or stiff foams have an appearance similar to shaving cream and expansion ratios greater than 10; 25 percent drain times are greater than those of fluid foams. Dry or stiff foams contain a large volume of air and are well suited for exposure protection, especially on vertical and inverted surfaces.

It should be understood that Class A foams depend entirely on their contained water for fire suppression. Wet and fluid foams contain more water per unit volume than dry foams and are consequently more effective in fire suppression. However, dry foams, which contain the least amount of water per unit volume, can be more appropriate where used for exposure protection.

Inspections, maintenance and tests

Normally, it is not necessary a special maintenance. Use and keep clean the nozzle.

Availability an service

The Sabo Española foam proportioner is available through a network of domestic and international distributors.
(To find a distributor near you contact Sabo Española).

Guarantees

For details of warranty contact Sabo Española directly.

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