FOAM

Foam is a highly efficient agent consisting of water, foam concentrate and air. A constant percentage of foam concentrate is steadily added to the water stream by inductors. The water foam mixture produced in this way is converted into foam in foam generators. The degree of foaming depends on the capacity of the foam generator, the foam concentrate and on the rate of induction.

 

 

In general foams are classified as follows:-

Low expansion foam expansion ratio 1:4

to

 1:20
Medium expansion foam expansion ratio 1:21

to

 1:200
High expansion foam expansion ratio 1:201

to

 1:1000

The decision as to which of the three types of foam should be used for fire fighting depends on several criteria. The fact that the fire is quickly covered with a sufficiently high, dense layer of foam is of decisive importance for successful extinguishing.

Low Expansion Foam.

Generally used at an expansion ratio of 1:5 to 1:7, ensuring very rapid spreading of the foam. The foam floats on liquids and adheres to inclined and vertical surfaces. Low expansion foam is mainly used against burning liquids e.g. gasoline, benzene, carbon disulphides, oils and lacquers, solvents etc. Due to its high specific weight, large throwing ranges can be achieved, as may be required on tankships, tank farms and as a result of aircraft crashes.

Medium Expansion Foam.

Generally used with a form expansion ratio of 1:40 to 1:150 and is especially suitable for fighting fires close to the ground for example in storerooms for inflammable liquids, in lock systems (in the event of tanker leakage's ), and in lacquer and paint factories etc. When applied in these cases medium expansion foam is extremely fluid, insensitive to heat, and stable enough to withstand effects of light wind. When medium expansion foam is applied in the lower expansion ratio ranges, throwing ranges of up to 12 metres can be attained which is often of great importance for effective extinguishing.

High Expansion Foam.

High expansion foam is extremely 'dry' and therefore very light. Depending on the type of foam generator, foam expansion ratios of up to 1:1000 can be achieved. Some kinds of foam generators produce more than one thousand cubic metres per minute, so that even large rooms can be foamed to the roof within minutes. The main field of application of high expansion foam is also the flooding of rooms affected or endangered by fire. Above all, production halls and storage rooms can be effectively protected in this way.

Premix Foam System.

When a guaranteed pressurised water supply is not available, Universal Fire have developed a "Premix Foam System" as shown above. In this system the water and foam concentrate are mixed at the correct proportions and contained within a pressure vessel - premix foam tank. Propulsion for the foam solution is provided by an inert gas (argon or nitrogen) cylinder through a pressure regulator. This system is completely "stand alone" in that it requires no other power, other than a 24 Vdc 1 amp to initiate discharge or manual operation. As environmentally friendly inert gasses are used, this system is suited for enclosed risks.