Breathing Apparatus Instructor Course

BREATHING APPARATUS INSTRUCTOR COURSE

KNOWLEDGE OF BREATHING APPARATUS INSTRUCTION

Learner outcome 1

To understand the use of a breathing apparatus set and its ancillary equipment.

Assessment criteria

1.1 To summarise the component features of the BA set and the ancillary equipment.

For example, using the Draeger PA93 BA set

INTRODUCTION

The PA93 is :-

A two stage;

open circuit;

self contained;

positive pressure;

compressed air breathing set which conforms fully to British standard BS EN 137.

The main component parts of the PA 93 are as follows

1.  Cylinder and Valve

2.  Cylinder connector and first stage reducer

3.  Pneumatic hoses

4.  Demand Valve

5.  Face-mask

6.  Whistle and gauge manifold & assembly

7.  Backplate and harness

A brief summary of a main component part would include its function and purpose, its design and material, its method of operation and any safety features.

e.g The PA 93 carbon fibre composite backplate is ergonomically designed and contoured to fit all users giving the unit a high degree of durability and comfort.The cylinder retaining strap is made from Kevlar and has a camlock fastening device for ease of handling. Carrying straps are built into the backplate. A rubber shocker is fitted to the base of the backplate.

The harness assembly is designed for quick removal from the backplate, for maintenance and cleaning. The harness consists of 2 padded shoulder straps and a waist-belt which incorporates a flame retardant membrane called Panotex (close cell padding).

The harness arrangement spreads the weight of the full set so that approximately two thirds of the weight is carried on the hips.

1.2 To explain the BA set and ancillary equipment in terms of:

a) use

The PA93 is a two stage open circuit Self Contained BA set. Older models were switchable between positive pressure and negative pressure operation, whereas the current model automatically operates on positive pressure mode once the first breath is taken.

The PA93 has an overall mass of approximately 16 kilograms and carries an alloy steel cylinder with a water capacity of 6 litres that can be pressurised to 300 bar.

Cylinder Capacity = 6l x 300 bar = 1800l

Using 40 litres per minute as the average person's working air consumption:

Full Duration = 1800l ÷ 40l/min = 45 minutes

Applying the 10 minute safety margin:

Working Duration = 45 min - 10 min = 35 minutes

The cylinder is secured to the carrying plate by a strap and the cylinder connection. The cylinder connection forms part of the unit that contains the pressure reducer (which reduces the pressure from the cylinder to 6 bar), the pressure gauge take-off and the low pressure warning whistle (which operates when the cylinder pressure drops to 50 bar). The warning whistle can be adjusted to sound at 68 bar to indicate 10 minutes supply left.

The medium pressure line feeds the demand valve from the pressure reducer, at which point there is a relief valve that will open at 10 bar if there is a malfunction with the pressure reducer.

b) limitations

The advantage associated with the deployment of BA ancillary equipment at an incident is to enhance the safety and efficiency of the BA Team in the tasks being undertaken.

The duration of operational use of electrical equipment governed by a battery source will be necessarily limited. Batteries will require regular replacements or recharging at extended incidents.

Additional considerations

Providing intrinsically safe BA Ancillary Equipment does not itself make the Incident safe from fire or explosion.

Consideration must also be given to:

·  Briefing the crews on any other environmental concerns or risk avoidance considerations within the structure or incident site.

·  The standard and correct use of the Firefighters’ clothing/PPE (e.g. awareness that static can be produced by some PPE).

1.3 To describe the operation of a BA set and ancillary equipment

A Breathing Apparatus Set is a portable unit that supplies the wearer with oxygen independent of the surrounding atmosphere. This allows personnel to survive in atmospheres that, due to the presence of poisonous gases or a reduced level of oxygen, are unsafe to breathe, i.e irrespirable.

The basic function of BA is to:

1.  Supply oxygen for normal breathing;

2.  Remove carbon dioxide produced by the body;

3.  Increase the supply during exertion.

BA must be strong but light-weight, comfortable to wear and very reliable. They must have easily operated valves that wont catch on projections when worn in confined spaces. There must be minimal resistance to breathing, and no undue heat build-up.

BA can be defined as:

1.  An Open Circuit. All exhaled air is released to the outside atmosphere. This system usually uses compressed air;

In positive pressure units, the demand valve operates when the pressure inside the face-mask is reduced to a point that is above atmospheric pressure.

In negative pressure units, the demand valve operates when the pressure is reduced to a point that is below atmospheric pressure.

In the event of a leak in the apparatus, positive pressure units are less likely to have the supply contaminated by the outside atmosphere than negative pressure units and there is less resistance to breathing, however they don't utilise the supply as economically and they are more likely to leak oxygen to a fire or other chemical reaction.

BREATHING APPARATUS

Air is supplied to the wearer at a breathable pressure by the demand valve when he/she inhales. When he /she exhales, the flow of air stops, and the exhalation valve in the face-mask opens, allowing the exhaled air to be discharged to the atmosphere.

As air contains 78% nitrogen and 1% other gasses, only 21% of the volume of the cylinder is the oxygen that is needed for respiration, and of the oxygen that is inhaled, about three quarters is exhaled. In other words, in an open circuit BA, only 5% of the volume of the cylinder is actually utilised.

As a result, even though they have a large cylinder, open circuit BA have a fairly short working duration. Also, as the rate of air consumption is dependent on factors such as fitness, nervousness and level of exertion, the duration varies substantially between wearers, and there is no procedure whereby the duration can be greatly extended should the person wearing the unit become trapped.

Purpose of BA Ancillary Equipment

The purpose of this Section is to outline the general principles for the selection of and the command and control procedures associated with BA Ancillary Equipment.

Equipment that is integral to the BA set e.g. DSU and the personal line, must comply with the relevant BS and EN standards.

Additional BA ancillary equipment should only be deployed within the risk area following a suitable and sufficient risk assessment. The risk assessment should identify the benefits conferred by that equipment toward the safety and effectiveness of BA Wearers, against the additional hazards, if any, presented by the carrying and use of that equipment within the risk area, particularly in a potentially flammable/explosive atmosphere.

The provision and use of non-intrinsically safe electrical equipment may be considered appropriate for all normal operational requirements, where such provision confers a significant benefit to the safety and effectiveness of BA Teams. Such equipment may include, for example, hand-held radios and thermal image cameras.

Operational pre-planning such as:

·  Site Specific Risk Information and plans

·  Section 7(2)(d) inspections

·  Generic Risks (GRAs)

may also identify the need for the provision of an appropriate standard of intrinsic/electrical safe ancillary equipment for BA Teams in situations and/or at specific risk sites within the fire and rescue authority area.

Briefing and debriefing BA Teams will confirm the type of BA ancillary equipment required for the tasks to be undertaken. Effective debriefing will also confirm that the equipment is proving suitable and effective in the operational conditions encountered within the incident.

1.4 To explain the testing requirements for a BA set and ancillary equipment

Breathing Apparatus is designed to support life. It is provided for life saving purposes. It is essential therefore that the very highest standards of testing are applied. To comply with the joint testing memorandum of the Home Office, H.S.E and DoT a rigorous testing and recording procedure must be maintained. Records, log books and any BA related electronic data should be considered as legally disclosable information, which may be relied upon in civil or criminal proceedings. It is essential therefore that BA equipment records and log books are always complete, accurate and accessible.

The testing procedure for a BA set can be found in Technical Bulletin 1/1997, Chapter 3 - equipment procedures. further information relation to each individual type of set can be found in manufacturers notes and operational guidance notes.

The explanation should consist of when the set and ancillary equipment is tested periodically and what each test include.

Any BA set or associated equipment check or test must conform to the specifications of the manufacturers’ instructions and guidance.

The 'General Check' of the apparatus should be based upon the relevant manufacturers’ guidance, but must include the following;

(a) the fastening of all finger-tight connections;

(b) the cylinder content, which at the time of test should be not less than 80% of full capacity;

(c) the operation of any supplementary flow facility;

(d) the operation of the apparatus by twice inhaling and exhaling deeply, and, whilst holding the breath, after the second inhalation, ensuring that no air flow from the apparatus is audible;

(e) a check of positive pressure protection by momentarily breaking the face mask seal

(f) ensuring the pneumatic integrity of all pressurised parts of the apparatus is maintained, including the face mask whilst pressurised to the normal working pressure (to the limits specified by the manufacturer);

(g) ensuring the low pressure warning whistle/device operates at the correct pressure; and any mechanical shut-off valve provided to isolate the pressure gauge hose, low pressure warning whistle/device or pressure gauge in the event of failure, operates effectively;

(h) ensuring the pressure gauge correctly returns to zero when the cylinder connection is closed and the apparatus is not pressurised; and

(i) test, by operation, the provision of any Telemetry equipment and ensure such equipment is maintained in such condition to provide immediate deployment when required.

(j) Face Seal Test. A face-fit seal must be ensured by means of the appropriate test.

The checks should be followed by:

a)  thoroughly examining the apparatus, its fittings and any cylinders and cover for damage or excessive wear;

b)  examining the face mask for clear vision;

c)  completing the entries on the tally attached to the apparatus. (It is acknowledged that on-call personnel may not complete tally entries until responding to an incident where BA may be utilised);

d)  ensuring the DSU operates effectively;

e)  inspecting the lamp to be used with the apparatus and checking it by operation;

f)  examining the personal line to ensure that it is fully serviceable and is correctly fitted to the harness of the apparatus; and

g)  checking that radio communications are operating effectively.

h)  where the apparatus is stowed on an appliance, checking that it is correctly secured to its bracket and that any fastening device is working correctly.

Monthly Test

This test should include:

(a) a minimum wearing duration of 50 bars. This can be part of normal wear at drill or incident provided it is of at least the minimum duration stated above, followed by:

(b) removing the cylinder from the apparatus;

(c) examining the cylinder retaining strap(s) and fastening(s) for damage or wear;

(d) examining the apparatus harness and its attachment points for signs of damage, wear or deterioration due to the action of chemicals;

(e) examining the attachment points, if fitted, for the DSU and the personal line;

(f) checking the security of all connection points in the air supply system;

(g) refitting a cylinder, within current test date, filled to at least 90% of the normal maximum pressure; and

Testing-General

The rubber and neoprene components of BA are liable to deteriorate from exposure to aggressive chemicals, ozone and from ageing. Such components should frequently be examined for signs of this deterioration and the advice of the manufacturers should be sought on the maximum service life of such components in ideal conditions.Replacement policies should reflect the advice provided by the manufacturers.

Testing of BA should be carried out only by persons who are qualified to wear the apparatus. Other than the procedures set out in this document, BA maintenance invariably requires the use of specialist test equipment and should be carried out only by personnel who have received the necessary training to a standard approved by the manufacturer of the apparatus.

A log book / test record must be permanently kept with each BA Set (except when it is carried on an operational appliance) detailing the:

(a) date and time of each test carried out on the apparatus and its ancillary equipment and the result

(b) type of test carried out, i.e. on acceptance, after use, monthly or annual, and the reason for it;

(c) name of the person carrying out the test;

(d) nature of any defects found; and

(e) nature of any repairs or adjustments and the identity of any person carrying them out.

If the logbook/test record is not utilised for daily or weekly general checks then suitable and sufficient alternative records must be maintained to ensure that these checks are being conducted and the results recorded.

Advantages

A robust BA testing and servicing programme provides set users with confidence that the BA set and ancillary equipment has been maintained to a high degree of operational readiness.

It provides assurance that any defects will have been identified and addressed before the BA set may be accepted for operational readiness.

A robust BA testing and servicing programme, together with an effective recording and auditing methodology, is essential to enable FRAs to meet their obligations under Health & Safety legislation.

The steps taken to ensure the operational readiness of BA may also assist in maintaining the competence of BA wearers, through frequent exposure to and handling of the BA set and its ancillary equipment.