Foam & foam making Flashcards
Please contact Phil Simpson if you notice any mistakes or have any suggestions
Foam production
How is the foam sytem controlled?
The foam system is controlled by a bank of switches and a ‘Round the Pump Inductor(RPI)’ which is located in the appliance pump bay.
Foam production
When using the RB101 with foam, what should be the branch settings?
400 l/min with the nozzle set to jet.
Foam production
What is the ‘Rolling in’ method of applying Low-Ex foam?
Rolling in – applying the foam to the ground in front of the fuel until a wall of foam builds and spreads across the surface of the fuel. This method has the advantage of driving the heat and flames away from the branch operator.
Foam production
When would the HI-Ex foam Generator Angus Turbex MKII be considered for use?
HI-ex foam is intended to flood totally enclosed spaces such as basements, warehouses & ships holds.
Foam production
What information should you know about the Akron quick attack monitor when using it with foam?
Akron Mercury Quick Attack Monitor;
- carried on DPL’s & PL’s
- stanard nozzle is unscrewed and replaced with the Master stream foam nozzle
- used to produce aspirated low ex foam
- there isn’t a flow rate setting so the pump operator provides 950 l/min at 7 bar
- can project foam upto 55 metres depending on wind & weather conditions
Foam production
How does foam extinguish a fire?
- Diluting the surrounding air with water vapour created as it evaporates
- Isolating fuel from the oxygen in the air
- Forming a sealing blanket over the surface of the flammable material, preventing vapour escaping
- Intercepting radiant heat from flames, preventing it from reaching the surface of fuel and causing further evaporation
- Cooling the fuel.
Foam production
How do you produce foam from the on-board supply?
- With the ‘PTO engaged’, hosereels closed and pump set to ‘low pressure’.
- Set `tank to pump’ switch to open.
- Check proportioner is in the closed position.
- Set the ‘foam tank to pump’ switch to open.
- Lay out delivery hose and open branches/monitor.
- increase pump pressure to 7 bar.
- Adjust RPI proportioner as required.
Foam production
How much foam is stored on board the Mercedes appliances?
Appliances are fitted with 120 litre tanks but should only carry approx 90 litres of foam, Each light on the foam tank indicator should equate to 30 litres of foam.
Foam production
How long should it take to start producing foam on the appliance?
It should take approx 45 seconds using the on-board system.
Foam production
What actions should be taken by the foam branch operator before closing their branch?
They should instruct the pump operator to close the RPI first!
Failure to do so will force inducted foam into the water tank contaminating the system and wasting the foam !
Foam production
When should the foam system be flushed out?
A foam system flush must be carried out after use at the incident.
(Consideration must be given to the enviromental impact)
Foam production
What type of foam is used by the LFB?
Low expansion foam using the RB101 or the Akron Quick Attack Monitor.
High expansion foam using the HI-Ex foam Generator Angus Turbex MKII
Foam production
What type of fires is Low-Ex foam suitable for?
Low-Ex is suitable for;
- storage tanks
- aircraft incidents
- vehicle fires
- road traffic collisions
- railway incidents
- liquid spill fires
- vapour suppression
Foam production
The scale on the RPI offers a choice of 3% or 6%, when would you use 3%?
A 3% mix is suitable for fires involving hydrocarbons; these fuels float on water and produce black smoke.
(if in doubt, use 6%)
Foam production
How many bulk foam units do the LFB have?
Three, based at Finchley, Sutton and Barking.
Foam production
When should an RPI (aka bucket) test be performed?
The bucket test should be performed weekly, This test replicates foam production from an external supply so therefore it’s a good way to practice foam production.
Foam production
An RPI test does not confirm that foam can be produced using the on board tank, what additional check should be made to ensure that the foam tank can ‘breathe’?
A visual inspection of the tank vent should be made.
Foam production
What is a ‘foam inlet and where would you expect to find them?
Buildings containing oil fuel, oil-fired boilers or other flammable liquids are protected by fixed piping through which foam can be pumped. The advantage of this is that foam can be applied without firefighters having to enter the compartment which is on fire.
The inlet is usually a tapered orifice, suitable for most types of LX branch. It is protected by a glass panel marked `foam inlet’, which also indicates the level of risk involved
Foam production
When estimating how much foam would be required to extinguish a fire, try to remember the example given in this answer!!
This fire was extinguished with the contents of one Merc foam tank and two foam branches.
Never under estimate the effectiveness of 6 minutes worth of foam application !
Foam production
What is the ‘gentle application’ method of applying Low-Ex foam?
Gentle application - applying foam to the surface of the fuel, with the foam making branch as far away as possible using the full trajectory of the foam stream. This reduces the impact velocity of the foamdue to the loss of speed of the foam stream as it travels through the air and the dispersion of the foam in the stream during transit.
Foam production
What attachment is required to enable a RB101 to be used with foam?
A foam aspirator is required.
Foam production
What hazards are presented when using Hi-Ex foam?
- Claustrophobia.
- Disorientation – vision, hearing and direction.
- Severely affected light penetration.
- Limited audibility of speech, automatic distress signal units (ADSUs), evacuation signals and low pressure warning whistles.
- Mini backdraughts and fire gas explosions due to trapped pockets of oxygen starved fire and unignited fire gases
- Difficulties in determining the travel and location of fire because of a reduction in the transmission of heat
- Signs of collapse as they may be obscured.
Foam production
What are the general safety considerations when applying Low-Ex foam?
- Visors down
- Always point jet away from fire until foam is flowing
- Apply gently to the surface of the burning fuel
- Apply from one point allowing foam to spread
- Do not plunge jet into burning liquid
Foam production
What is the method of application of Hi-Ex foam?
Wherever possible, generators should be placed in the open air, as products of fire can affect volume and stability.
If a large volume of foam is being used to penetrate a compartment with little ventilation, it has to overcome a back pressure of the build up of products of combustion, which can halt the spread of hi-ex. When an incident is ventilated to prevent this happening, all openings must be covered by hosereels or hand-controlled jets to prevent fire spread. Never inject water into the compartment as this will break down the foam
Foam production
How far can the foam jet be projected to when using the RB101?
Up to 23 metres depending on wind & weather conditions.
Foam production
What is the consumption rate of foam when the RPI is set to 3%?
With the RPI set at 3%, a branch consumes approx 15 litres of foam compound per minute, so therefore 90 litres will last 6 minutes.
Foam production
What is the ‘Off wall – indirect’ method of applying Low-Ex foam?
Off wall – indirect application – directing the foam towards / or deflecting off an object (a wall for example) allowing the foam to sink to the base of the object and spread across the surface of the fuel forming a blanket. The disadvantage of this method is that it can drive the heat and flames towards the branch operator.
Foam production
What branches can foam be used with?
The RB101 & the Akron quick attack monitor with aspirators can be used for firefighting with foam.
Foam must not be used through the hosereels !
Foam production
What is the ‘Rain down’ method of applying Low-Ex foam?
Raindow – applying the foam into the air above the fuel, allowing the foam to drift down onto its surface. It can take time to build up a sufficient layer of foam and the direction and strength of the wind have to be considered. Itmay not be possible to use this method at a large fire because of the stong updraft wind a large fire will generate.
