Explosion lors d’une intervention sur un groupe de froid d’un café.
Ci après le rapport complet des faits, les conclusions, les références aux normes et lois australiennes.
Document en Anglais.
MINUTES Forming ENCLOSURE TO:
TO:THE MANAGER, COMMUNITY SERVICES TEAM.
SUBJECT: SUMMARY OF INVESTIGATION OF AN ACCIDENT AT CAFÉ GROVE TO CON ARGY AND TREVOR HANLON.
LOCATION: THE GOLDEN GROVE VILLAGE SHOPPING CENTRE, CNR. THE GOLDEN WAY & THE GROVE WAY, GOLDEN GROVE, SOUTH AUSTRLAIA 5125
INSPECTOR: GRAHAM STEPHENS
INSPECTOR: PETER COCKERHAM
On Monday the 5th July 1999, DAIS Workplace Services was notified of a serious accident by Constable Ian Brumby, South Australian Police, Tea Tree Gully Patrols, who advised Lyn Barnett, Team Manager, at approximately 1045Hrs. Lyn Barnett advised Senior Consultant Peter Cockerham who spoke to Constable Brumby to ascertain more details. A record of immediately notifiable work related injuries form was filled out.
Con Argy, the manager of Café Grove and Trevor Hanlon, refrigeration mechanic employed by Contract Refrigeration Services received serious burns to their faces and bodies as a result of a fire/explosion when a condenser pipe in a refrigerator ruptured and the escaping gas ignited.
Both injured persons were taken to the Modbury hospital for treatment. Trevor Hanlon was then transferred to the burns unit of the Royal Adelaide Hospital.
Peter Cockerham attended the scene and arrived at approximately 1130Hrs. There had been a fire/explosion inside the Café Grove with police, fire and ambulance personnel in attendance. Peter Cockerham was informed that two persons had been burnt in the explosion, one seriously.
Peter Cockerham talked to the Police, MFS Fire Cause Investigators, and Angus Roberts, employer of Trevor Hanlon and was told that Trevor Hanlon had been working on an under shelf refrigerator/freezer, commonly referred to as the « beer fridge ». While at the scene details of persons present and that of witnesses were obtained.
DETAILS OF INJURED PERSONS
Injured person: Con Argy
Address: 23 Ward Terrace Gawler East
Age: 62 years
Injured person: Trevor Hanlon
Address: 17 Reid Street Hectorville
Age: 40 years
Occupation: refrigeration mechanic
Employer: Contract Refrigeration Services
Time of accident approximately 1015hrs.
When interviewed on Wednesday 25 August 1999 Trevor Hanlon confirmed the manner in which this accident happened.
Early Monday morning on July 5, 1999 Trevor Hanlon went to the premises of Angus Roberts and picked a cylinder of Care 50. Using a van from Contract Refrigeration Services Trevor Hanlon went to Café Grove arriving at approximately 0900Hrs. Trevor Hanlon went inside the Café with his tools and the cylinder of Care 50. Con Argy and Paul Tucker, (kitchen hand) were present. Trevor Hanlon removed the front grill of the « beer fridge » and connected his gauges to the low-pressure side of the compressor.
Trevor Hanlon was crouching in front of the unit at the time when he heard a loud noise, (liquid and vapour under high pressure), and a cloud of liquid, vapour and oil coming towards him. Paul Tucker leaned over the counter and Con Argy also became aware that something was wrong. Trevor Hanlon told Paul Tucker to turn everything off, as he knew that Care 50 was flammable. Trevor Hanlon then pulled out the electrical cord. Immediately a blue flash came from the bottom on the unit. Both Trevor Hanlon and Con Argy were engulfed in a ball of flame. As Trevor Hanlon ran from the shop through the doorway into the mall he collided with one of the female customers as they were running out of the café. When the MFS arrived Trevor Hanlon told them that a cylinder of flammable gas was still inside the restaurant. MFS personnel removed the flammable gas cylinder to the footpath outside of the restaurant.
On Tuesday 6 July 1999 I proceeded to Café Grove and arrived at approximately 0930Hrs. and introduced myself to Carmel Argy-owner with her husband Con Argy. I proceeded to take notes and photographs of the accident scene. I observed a counter refrigerator located behind the front counter in which the fire/explosion had occurred. I was shown receipt number 534 dated 1/7/99-2/7/99 by Carmel Argy indicating repairs to the freezer. I went to the newsagent and made a copy of this receipt and returned the original to Carmel Argy.
Carmel Argy told me that the unit was to be replaced early next day ie. Wednesday 7 July 1999. I left instructions that I would be coming back and that I would be seizing the unit and that I would issue a receipt.
On Wednesday the 7 July 1999 at approximately 0900hrs. I again proceeded to Café Grove and introduced myself to Andrew Argy son of Con Argy, as the compressor unit was to be replaced with a new unit that morning I noted the following persons were present:
a) Andrew Argy, son of Con Argy the owner.
b) Russel Brown, Manager of Elgas.
c) Ron Monk, Branch Manager/Loss adjuster, Wyatt Gallager Bassett.
d) Elliot Errington, The new Manager of Café Grove.
e) Angus Roberts, Contract Refrigeration Services.
Angus Roberts proceeded to replace the refrigeration unit in the « beer fridge » with a new unit (Kirby). The old unit was placed on top of one of the tables and I allowed the above interested persons to look at the unit but they were directed not to touch the unit in any way.
Russel Brown took photographs, and I then placed the unit in the boot of my car and issued receipt, number 012008 to Andrew Argy. I also directed Russel Brown to supply me with information on Care 50 refrigerant gas.
I also checked with Angus Roberts to see that the new refrigeration unit was charged with an appropriate non-flammable refrigerant gas. I was informed that he had charged the unit with R22.
On my arrival at the office I then placed the unit in a secured cupboard on the 4th floor of the office of DIAS, Workplace Services, located at 1 Richmond Road Keswick.
From my investigations into this accident, including observations, witness statements and interviews, I have concluded that Con Argy owner of Café Grove and Trevor Hanlon, employee of Contract Refrigeration Services received first, second and third degree burns to their bodies as a result of charging the counter refrigeration unit, « the beer fridge » with a hydrocarbon flammable gas by Angus Roberts on Friday 16 April 1999. The following information was confirmed:
The actions of Trevor Hanlon on the day of the accident, Monday 5 July 1999, cannot in any way be proved to have contributed to the rupture of the return bend.
The report from Bemet Services Pty Ltd, also substantiates our findings into the cause/causes of this accident.
The return bend on the condenser had been repaired by braze welding on the elbow due to the presence of a small hole, see report from Bemet Services photograph 25 in appendix 2 of this report. The braze welding caused deformation on the inside of the return bend, thus altering the grain structure and weakening the return bend. The condition of the paint and paper stickers on the condenser would indicate that the repair could have been carried out before the condenser was painted and as there are no scorch marks on the paper sticker or burn marks on the paint work, or indications that the repair had been covered by the application of more paint would indicate that the repair could have been performed at the factory.
PRIOR CONVICTIONS OR DIRECTIONS
A search of Departmental records has revealed that Contract Refrigeration Services has no previous convictions or received any directions.
From the information received from statements of witnesses, Bemet Services Pty Ltd and the Elgas Refrigerant Training Manual the following considerations were taken into account in reaching my recommendations.
Inadequacies in the Elgas training manual. (appendix 17)
In the section, Performance of the Care Range of Refrigerants, (page 8).
« An ignition source at a temperature of more than 460 degrees C is also needed for combustion to occur » This statement is very open in that it can infer that sparking from electrical equipment will not ignite vapours. Sparks from electrical equipment can produce high temperatures for a very short period of time and can certainly ignite flammable vapours with in the correct vapour to air concentrations.
Also on page 9 under the heading of General Safety Issues at the second dot point « eliminate ignition sources by using only sealed or non-sparking electrical components (general experience with hydrocarbons in Europe shows that there are unlikely to be problems with conventional refrigeration components) and by eliminating flames ». This statement is contradictory in that it mentions in the first part of using only sealed or non-sparking electrical component then goes on to say that it is unlikely that the operator will encounter any problems with conventional refrigeration components. This certainly is not true in Australia, as there are many sources of ignition in a refrigerator.
In the section. Handling of Care Refrigerants, (page 11) under the heading Drop-in Procedures in paragraph 8 « Seal the electrics on the refrigeration system using a sealing compound such as mastik or gaskets. This is to prevent air, which may be contaminated with flammable refrigerant in the event of a leak, entering an electrical component which could spark and therefore be an ignition source. It may be preferable or a requirement to replace electrical items with equipment approved to operate in the correct hazard zone ».
The first part dealing with sealing the electrical equipment using mastic is not good practise and it certainly would not comply with AS 2430 Classification of Hazardous Areas and AS/NZ 2381.1-1999 Electrical Equipment for Explosive Atmospheres Selection, Installation and Maintenance Part 1 General Requirements. The second part which deals with replacing the electrical components is certainly closer to the requirements of AS 2430 Classification of Hazardous Areas. This statement is inconsistent with the rest of the above statements.
From the above deliberations I would therefore recommend that in this instance the Department take no further action against Contract Refrigeration Services.
As this incident has ramifications through out the refrigeration industry as a whole, including air conditioning, the commercial, industrial, and private sector, also the motor vehicle industry, and to help assist the reader in understanding three important references in terminology, the following definitions are included:
a) Add – in refrigerant
refrigerant alternative – can be added to equipment without removing original refrigerant.
b) Drop – in refrigerant
refrigerant alternative – can be added after removal of original refrigerant.
c) Retro refrigerant
refrigerant alternative – can be used after significant modifications to equipment.
It is recommended that the Department take the necessary steps to have:
1) Drop – in refrigerant charging, of hydrocarbon refrigerant gasses, (flammable) such as the Care range and the Esanty range of gases and any other brand name restricted to that of charging only those systems that have been identified through an assessment process by a suitably qualified person, as being suitable for this type of charging.
2) Retro refrigerant charging of hydrocarbon refrigerant gasses, (flammable) such as the Care range and the Esanty range of gasses any other brand name restricted to that of charging only those systems that have been fully converted to eliminate all sources of ignition and make it a requirement to consult with the manufacturer for their recommendations. The recommendation of the manufacturer is to be headed at all times. The requirements of this part of the recommendation 2. (2) is to also apply to part 2. (1) of this recommendation.
3) The refrigeration installation, whether it is, add – in, drop – in, or retrofit method is to comply fully with Division 3.3, Occupational Health Safety & Welfare Regulations 1995, also the requirements of Australian/New Zealand Standard 1677.2 1998 Refrigeration systems part 2: Safety requirements for fixed applications.
4) Australian/New Zealand Standard 1677.2 1998 Refrigeration systems Part 2: Safety Requirement for fixed applications is to be given the status of a code of practice.
5) Workplace Services to develop a HAZARD ALERT relating to the above dangers involved in retro charging of refrigerated units with hydrocarbons gasses and issue the hazard alert to the following:
a) All country offices of Workplace Services.
b) The refrigeration industry (RACCA).
c) Interstate counter parts.
d) Other interested organisations.
OCCUPATIONAL HEALTH & SAFETY
COMMUNITY SERVICES TEAM.
The following sections of the Occupational Health, Safety and Welfare Act 1986 are included for information purposes.
The Occupational Health Safety and Welfare Act 1986
Plant includes –
a) any machinery, equipment, appliances, implement or tool;
b) without limiting the application of this Act to any plant used at work or at any workplace, any plant to which this Act extends by virtue of schedule 2:
c) any component, fitting, connection, mounting or accessory used in or in conjunction with any of the above.
Extension of Act to Specific Plant
1. Subject to any exclusions or modifications prescribed by the regulations, this Act extends to the following types of plant (whether or not such plant is situated, operated or used at any workplace):
(e) pressure equipment.
2. For the purposes of clause 1 –
« pressure equipment » means –
(b) any pressure vessel (other than a boiler), being a vessel which is subject to internal or external pressure greater than atmospheric pressure and includes any interconnected part, component, valve, gauge or other fitting up to the first point of connection to the piping; or
(c) any assembly (other than a boiler or pressure vessel) of a prescribed kind consisting of pipes, pipe fittings, valves and pipe accessories which are subject to internal or external pressure.
Bearing these definitions in mind I am of the opinion that the compressor unit which failed in this incident falls within the scope of the above definition of plant as defined in the definitions of the Occupational Health and Safety Act 1986 and pressure equipment under schedule 2 of the Act. The compressor in question operates at a pressure of approximately 2,400 Kpa on the high side.
1.Responsibilities of the employer are defined in section 19 of the Occupational Health Safety and welfare Act 1986;
Section 19 (1) An employer shall, in respect of each employer employed or engaged by the employer, ensure so far as is reasonably practicable that the employee is, while at work, safe from injury to health and in particular –
a) shall provide and maintain so far as is reasonably practicable –
(iii) plant and substances in a safe condition.
There are also responsibilities for the owner of the plant under section 24A.
2. Responsibilities of person who modifies any plant are defined in section 24 of the Occupational Health Safety and Welfare act 1986;
Duties of manufacturers, etc.
24 (2) A person who erects, installs or modifies any plant to which this subsection applies shall ensure so far is reasonably practicable that it will be safe –
a) when properly used and maintained; and
b) when subjected to reasonably foreseeable forms of misuse.
Part 3 Division 3.1 of the Occupational Health Safety and Welfare Regulations 1995 deals with specific requirements relating to plant, hazard assessment, risk identification, control of that risk, repair, alteration, and plant under pressure.
3.1.1 The purpose of this part is to protect the health and safety of persons from hazards arising from plant and systems of work associated with plant by –
a) ensuring that hazards associated with the use of plant in the work place are identified and risks to health or safety are assessed and controlled by –
b) eliminating or, where that is not reasonably practicable, minimising, risks to health or safety; and
DIVISION 3.3 GENERAL REQUIREMENTS FOR HAZARD IDENTIFICATION,
RISK ASSESSMENT AND CONTROL OF RISK
3.3.1 (1) this regulation requires the identification of all reasonably foreseeable hazards to health or safety arising from plant, or systems of work associated with plant.
(2) in particular, any hazard associated with the following factors must be identified, insofar as they are relevant to the design, manufacture, erection, installation commissioning, use or dismantling of the plant:
(a) the suitability of the type of plant for the particular task;
(f) the generation of hazardous conditions due to pressurised content, electricity, noise, radiation, friction, vibration, fire, explosion, temperature, moisture, vapour, gases, dust, ice or hot or cold parts;
(g) the failure of the plant in a case involving the loss of contents, loss of load, unintended ejection of work pieces, explosion, fragmentation or collapse of parts.
3.3.2 The method used for risk assessment must adequately address the hazards that have been identified and include one or more of the following;
a) a visual inspection of the plant and its associated environment;
d) technical or scientific evaluation;
e) an analysis of injury and near miss data;
f) discussions with designers, manufacturers, suppliers, importers, employers, employees or other relevant parties;
Control of risk
3.3.3 (1) one or more of the following must be used to eliminate or, where that is not practicable, minimise any risk to health or safety;
(a) firstly, the application, so far as is reasonably practicable, of engineering controls, including substitution, isolation, modifications to design and guarding;
(b) secondly, if steps taken under paragraph (a) do not minimise the risk, the application, so far as is reasonably practicable, of administrative controls, including safe work practises.
As the manufacturer of this piece of plant, Kirby Refrigeration does not recommend the use of hydrocarbon refrigerant gasses in their compressors. This document dated March 9 1998, and addressed to all customers relates to the use of hydrocarbon refrigerants. In the last paragraph it states:
« Currently the range of products manufactured and/or sold by Kirby Refrigeration are suitable only for non-flammable refrigerants as specified by Kirby Refrigeration. The use of Group A3 refrigerants, ie: Hydrocarbons is not recommended unless authorised or approved by the Engineering Manager of Kirby Refrigeration. »
Therefore Angus Roberts of Contract Refrigeration, by his actions of changing the refrigerant fromR22 to Care 50 (flammable) a different one to that specified and recommended by the original manufacturer, must accept the responsibility of this modification.
Australian Standard 1677 – 1986 Refrigerated Systems. The AE9MG unit, manufactured by Kirby Refrigeration and used in Café Grove, including the condenser had been designed and constructed to the requirements of the above standard. This standard gives the limitations on the various combinations of refrigeration, refrigeration plant location, refrigeration plant types, and type of occupancy.
Café Grove meets the criteria of class B occupancy such as shops, offices, restaurants, public buildings etc. The full details of this classification can be found in appendix 21 of this report.
In table 2.1 of this standard, System Application Requirements, refrigerant group 3 Hydrocarbon gasses (flammable), for area class B rule 7 is to apply.
Rule 7 stipulates that it is not allowed ie. Group 3 hydrocarbons gases (flammable gases such as LPG) is not permitted.
This ruling would be consistent with the recommendation of Kirby Refrigeration a division of James N Kirby, manufactures of the unit, and the letter dated March 9 1998 and addressed to all customers which states « Currently the range of products manufactured and/or sold by Kirby Refrigeration are suitable only for non flammable refrigerants as specified by Kirby Refrigeration. The use of Group 3 refrigerants, ie Hydrocarbons is not recommended unless authorised or approved by the Engineering Manager of Kirby Refrigeration ». A copy of this document is located in appendix 3 of this report.
The wall thickness of the copper tubing used in the manufacture of return bend has been upgraded from 0.41mm to 0.56mm to allow for higher operating pressures.
When Australian New Zealand Standard 1677.2: 1998 Refrigeration Systems Part 2: Safety requirements for fixed applications, published on 5 January 1998, supersedes the previous standard, came into operation there were significant changes which includes the use of hydrocarbon refrigerant gasses in certain circumstances.
This standard applies to new refrigeration systems, extensions and modifications of existing systems. It also applies in the case of the conversion of a system for use with another refrigerant. The category of occupancies has been changed from the alphabetical system to a numerical system. In relation to Café Grove the new category of occupancy is now category II including small restaurants.
AS/NZ Standard 1677.2:1998 Clause 2.6.3 Category II occupancies States « Group A3 refrigerants hall be permitted, as for Category I occupancy, with a minimum charge restricted to 2.5Kg for refrigerating systems installed in an occupied space. »
Clause 2.6.2 Category I occupancies Group A3 refrigerants shall be permitted only in systems with a refrigerant charge of up to 1.5Kg for each individual system, provided sudden loss of refrigerant could not raise the concentration of the refrigerant to or above the practical limit in an occupied space and provided there is no sources of ignition, eg. unsealed electrical contacts associated with the refrigeration system or located in an area where the refrigerant could gather in the event of a leak.
Very small sealed systems with refrigerant charge of 0.25Kg or less may be sited in any location or category of occupation provided that there are no sources of ignition, eg. unsealed electrical contracts associated with the refrigeration system or located in an area where the refrigerant could gather in the event of a leak.
The electrical equipment, such as the current type of relay, used in unit AE9MG, as specified by Kirby Refrigeration is a source of ignition therefore not suitable for use with hydrocarbon refrigerants (flammable). There are other sources of ignition with in the unit space of the compartment refrigerator at Café Grove, such as the power point, thermostat, electrical junction boxes, and the high-pressure switch.
AS/NZ 1677.2:1998, Clause 4.7.6 Flammable refrigerants
188.8.131.52 General. For refrigerants of group A2, A3, and B2 the restrictions on use given in section 2 shall apply.
Note For further guidance, see Appendix D. A recommended assessment procedure for use of Class A3 refrigerants at a particular site is given in Appendix E.
Appendix E Recommended Assessment Procedures for the Use of A3 Refrigerants
E3 Manufactures Advice The Manufacturer of the original refrigeration source equipment or another suitably qualified person should be consulted to advise on the safety of the proposed refrigerant in the system under consideration. The advice should relate to the safety of the equipment and the compatibility of materials and lubricants in the refrigerating source as a unit. Comments on the advice received should be recorded in the relevant section of Fig.E1.
Australian New Zealand Standard 1677.2:1998 is not referenced in the Occupational Health Safety & Welfare Regulations therefore this standard has the standing or a recommended method of performance or doing something.