me narrate you a real story.

A ship was to arrive in a US port after a long sailing. Foam sample for fixed foam system was sent for testing at last port. Three days before arrival, the results of the foam sample analysis were received.

The test had failed. USCG did not allow the vessel to berth. The foam sample was redrawn and sent for analysis. Even though the sample passed, more than one day was lost in this process.

Question is, why did USCG not allow the ship to berth? They must have felt that it is really dangerous to allow the tanker to berth with an ineffective foam system.

Do we take our firefighting equipments and system this seriously? Let us admit it, we don’t !!!

The first step of showing the seriousness is knowing everything about our equipments.

In this article, I will discuss fixed fire fighting foam system on board ships.

Let us fire it out !!!

How foam extinguishes the fire

Fire fighting foam used on ships has three elements.

Foam concentrate

water

air



Foam concentrate is mixed with water in a correct proportion to form a foam solution. This foam solution when agitated with air produces foam.

Foam extinguishes the fire in three ways

It forms a blanket and thus removing the supply of oxygen to the fuel, the effect called smothering.

The foam blanket does not allow the fuel vapors to generate, thus cutting the fuel supply to the fire

Since foam has water, it cools the fuel surface



Main terms used in defining the foam

Now let us get to know few of the terms associated with foam.

Expansion ratio

We all understand how a foam solution is formed. The form concentrate is mixed with the sea water and air at the foam monitor causes this foam solution to generate foam.

In other words, foam concentrate that we have in foam room tank expands to generate foam. Different foam concentrate has different capacity of how much foam these can generate from a fixed quantity of foam concentrate.

The ratio of the volume of foam generated (finished foam) to the foam concentrate used in that is called expansion ratio of the foam.

The foam with expansion ratio between 1:2 and 1:20 is called low expansion foam.

Foam with expansion ratio between 1:20 and 1:200 is called medium expansion foam.

Foam with expansion ratio above 1:200 is called high expansion 

свернуть