Historical Fires

Why and when is Breathing Apparatus used
The air contained inside a standard firefighters breathing apparatus set is just normal air that has been compressed to fit inside the cylinder so that it will last longer than a few breaths which is all you would get from uncompressed air in a container of the same size.
When we go into fire and toxic atmospheres if we did not have fresh air to breathe we would not get more than a few steps inside the building before collapsing from the poisons in the air of a fire. We could not fight a fire from inside a building and could not spend time searching for casualties who may be trapped inside.
In addition to fires there are other times when breathing apparatus is used such as in sewers where gases such as methane build up or at chemical incidents where the massive variety of poisonous gases manufactured for industrial use are potentially present.

General Description

Facemask
Polycarbonate high visibility visor with inner ori-nasal mask to prevent misting up. The mask itself is constructed from neoprene rubber or silicon and is held in place by a five point adjustable harness with each point being adjustable. All sets are required to be positive pressure to prevent an inflow of toxic gases if the facemask is dislodged. Masks have a supplementary air flow button to allow extra air to be pushed onto the face if the need arises. The demand valve is usually activated on a first breath system which switches the sets into positive mode.

Cylinder
The cylinder is a 9 litre water capacity or 1800 litres of air charged to 207 bar or 3000psi. Brigades have at present only one cylinder on each set. The contents is 45 minutes using an average of 40 litres a minute. However if a firefighter is working hard or in a harsh environment such as extreme heat this time can be drastically reduced. Alternatively a slower pace of work such as gaining information at a chemical incident may extend the duration but 40litres a minute is taken as an average use (in Ireland anyway!)
Cylinders are at present changing to carbon composite lightweight throughout the country. A slip on cover made from nomex or plastic is placed over the cylinder to prevent scuffing and general marking of the cylinder.
On Dublin Fire Brigade cylinders the open close valve handle which is on a spring and has to be pulled out to turn off the cylinder. This safety feature was introduced after air was accidently turned off when a valve rolled closed while coming down a stairwell with the valve wheel rubbing on the railing.

Backplate
Previously made from stainless steel but changing now to polycarbonate heat resistant plastic.
The cylinder is held on via one or two straps. The backplate is designed with the comfort of the wearer in mind.

Harness
Made from black nylon webbing. The waistbelt incorporates a stiffener so that it comes easily to hand when donning the set. Buckles are snap fit glass reinforced plastic. The shoulder harness is padded with loops for the air hoses.

Contents Gauge
A Bourdan type gauge, this is measure in bars ( 1 bar =14.7 psi) and reads up to 250 bars  (3675 psi). It is luminous and waterproof with a blow out back which will vent full cylinder pressure in the event of a failure of the pressure system.

Ancillary Items
In addition to the set and cylinder each set must have the following items attached before entry into an incident. It should be noted that wearers will be refused entry if these any of these items are missing.

Distress Signal Unit
A device which signals that a firefighter is trapped and needs assistance. Also incorporated in some models is a evacuation signal in case of possible building collapse etc.
The Dixtron DSX Mark 2 is the one described here. This is an electronic device permanently attached to each set. Before going into the incident a magnetic key (attached to a tally) is slid from the device which activates the D.S.U. If after 30 seconds the device does not sense any movement it go into pre-alarm mode activating a alarm. If after another 10 seconds the wearer has not moved it then goes into full distress alarm and cannot be switched off until the wearer is returns outside and the key reinserted. This ensures that even an unconscious firefighter can issue an alert.
Once activated the crew begins an entrapped procedure and begins to relax and conserve their air to wait for rescue.
The evacuation signal is a manual button and when the wearer hears or receives an immediate evacuation signal he presses his alarm and retreats outside. Other wearers will do the same.
 

Tally	Station	.	Cyl No.
The tally is a yellow plastic strip  attached to the distress  signal unit key.	Name ......................	Cyl press	Time in

Before entering the incident he hands it to the Breathing Apparatus Entry Control Officer who puts it in the breathing apparatus incident board. On the tally is the Firefighters name / time in / contents of cylinder and station. This allows the B.A.E.C.O. to determine when the crew should be out and who and where they are.

The Entry Control Officer wear a checkered vest / tabard with B.A. Officer on the back to identify them to breathing apparatus crews.

Personnel Line
Small diameter line of 6 metres in length. It is in two sections with a clip which releases to extend it to full length. The first section is 1.25 metres and the second 4.75 metres.Iit is used by firefighters to attach to each other or to a guideline or both to maintain physical contact which is required at all times.

Torch
Intrinsically safe which means it will not create sparks either by being dropped or through the act of switching it on / off., used to see in the dark!

Guide Lines
A small dia. line for the purpose of allowing subsequent BA teams to proceed directly to a fire in a smoke logged building by following the route of the line while attached to it via a snap hook.
The line is housed in a small bag which pays out the line as the team advances. It is 60m (200’) long with 2 separate knots every 2.5m. These knots allow the team to tell by touch if they heading to the fire or the exit. Personal lines are used to attach to this line.

Breathing Apparatus Procedures
Main Points

• Minimum 2 maximum 5 firefighters on a breathing apparatus team.
• Must maintain physical contact via touch or personal line.
• Must be out before low pressure air whistle sounds
• Must deposit and collect tallies from B.A.E.C.O.
• Must don masks in fresh air and not remove until returned outside.
• Air and time out calculated on the lowest team members cylinder contents.
• Minimum contents on entry is 80% of a full cylinder i.e. 160 bar (taken as 170 on station level)

Working duration on full cylinder of 1800 litres of air is 35 minutes with 10 minutes safety i.e. total 45mins.

All firefighters in the Republic of Ireland must follow a set of breathing apparatus procedures as laid down by the Department of the Environment. The procedures are enclosed in a 70 page long A4 size book which is available for about 8 Euro from the Government Publications Office located on Molesworth Street off Dawson Street Dublin 2.