Equipment Design Standards

Our Safewell ATEX Breathing Air Compressor is manufactured in accordance with European Directives eg, Machinery, Atex, Pressure Equipment, Noise, EMC Directives and all applicable Harmonised Standards to the Directives which, by following these standards, provides Presumption of Conformity to the Directives. The machine also has SIL (Safety Integrity Level) validated safety functions according to IEC61508 which have been validated by TUV certified competence.

The functional safety expert behind the validation of the compressor safety design is an internationally certified machine safety expert (TUV Nord) and an internationally certified functional safety professional (Exida), other contributors and guidance to the content of the safety design has been given by certified functional safety experts from Exida and functional safety managers from Siemens AG.

The relevant harmonised standards listed in the official journal for the ATEX directive 2014/34/EC relevant to the Safewell compressor are the EN IEC 60079 series of standards, EN 1127-1, EN IEC 80079-36, EN IEC 80079-37 and EN 50495.

Relevant parts of EN IEC 60079, EN IEC 80079-36, and EN IEC 80079-37 are applied and this is common practice for equipment used in potentially explosive atmospheres. We also apply the requirements of EN 50495.

EN 50495 was a result from the SAFEC project completed in 2010. The SAFEC project had the overall   objective to produce a harmonised system for subdivision of safety devices which are used in potentially explosive atmospheres, together with a methodology for selecting the appropriate subdivision of safety device for any particular application.

The SAFEC partners were the Health and Safety Laboratory of the Health and Safety Executive (HSL) in the UK (the project coordinator), the Deutshe Montan Technologie (DMT) in Germany, the National Institute for Industrial Environment and Risks (INERIS) in France and the Laboratorio Oficial J.M. Madariaga (LOM) in Spain.

EN 50495 guides the use of safety integrity levels (SIL) and safety lifecycle process of EN IEC 61508 to ensure the continued reliability of electrical control safety critical shutdowns for explosion protection. Shown below is the introduction and scope of EN 50495:

‘Safety devices, controlling devices and regulating devices which are used for the protection concept of equipment for explosive atmospheres, shall function reliably for the intended purpose. This shall be expressed in terms of some measure of confidence that the devices will be able to maintain a required level of safety at all times. This measure of confidence needs to be in conformity with CENELEC standards of the series EN 60079 and EN 61241 for apparatus for use in explosive atmospheres and relevant control standards.

CENELEC identified the need for research to determine whether existing and proposed standards in the field of safety-related control systems were suitable for this purpose. The SAFEC partners were the Health and Safety Laboratory (HSL) of the Health and Safety Executive in the UK (the project coordinator), the Deutsche Montan Technologie (DMT) in Germany, the National Institute for Industrial Environment and Risks (INERIS) in France and the Laboratorio Oficial J.M. Madariaga (LOM) in Spain. The result of this project recommends the application of Safety Integrity Levels as specified in EN 61508-1 for safety devices.

This European Standard specifies the requirements of electrical safety devices, which are used to avoid potential ignition sources of equipment in explosive atmospheres. This also includes safety devices, which are operated outside areas with explosive atmospheres, to guarantee the safe function of equipment with respect to explosion hazards’.

Safewell and our supply chain partners feel that the application of BS EN 50495 is very relevant. Safety products such as a BA Compressor which are used in ATEX zones should have validated safety functions (IEC61508) to assure reliability in accordance with safety risk ALARP principles.

NORSOK COMPLIANCE TO Z-015 Rev 4, TEMPORARY EQUIPMENT

In addition to these directives and standard, our ATEX Breathing Air Compressor unit has also been designed and manufactured in accordance with Norsok Z-015 rev 4, and associated standards, this has been completed with minor deviations, these are for design areas that are either not applicable or, where we have exceeded the requirements of the applicable normative sections of this standard for U02 type equipment, air compressors.

Deviations from the Z-015 standard are listed below:-

Section 4.3.2               Low oil pressure is not monitored

The manufacturer monitors temperature of the oil and discharge air with SIL 2 validated safety functions. This provides two high integrity monitoring circuits which ensure there is no ‘high oil temperature’, or ‘low cooling oil level’. This will give early indication of oil pressure failure as temperatures will elevate quickly. Complete disconnection on gas detection

The manufacturer allows for intrinsically safe circuits and control circuits to remain live after safe shutdown for diagnostic purposes. The circuits that remain live, are either, intrinsically safe or located within the Exd control panel, therefore they do not present an ignition risk in ATEX zone 1 or 2.

Section 4.5.1.e       Components marked with TAG numbers

The document pack includes a Hazardous Equipment list indicating the model and serial numbers of all ATEX certified components allowing direct identification to facilitate in periodic testing in accordance with EN 60079-17:2014. The document pack also includes a pressure equipment list for all of the certified pressure equipment such as vessels, pipes to facilitate periodic inspection and testing. Therefore individual tagging of components is deemed unnecessary and for reasons due to space constraints it would not be practical to provide these.

Section 4.4.2               Fire protection & alarms

The manufacturer does not fit fire alarms or fire extinguishing equipment to the unit. This is due to space constraints, and that fire protection methods are employed by end users.

Section 5.7.4         Motor protection:- Earth fault protection.

Earth fault protection is not fitted due to space constraints within the Exd panel.

We do monitor the internal motor windings temperature using a SIL 1 safety loop, the motor also has a class 10 tripping characteristic thermal overload device upstream of the motor, if either of these devices detect abnormal conditions the machine is immediately stopped. In addition, the machine also has a combined thermal/magnetic protective device to operate in the event of a short circuit. The motor connection cable is <1m long, armoured, and run within the enclosure, therefore short circuits in the cable are deemed negligible.

It is essential that all those involved in the planning, design, development, implementation and management of computer-based systems used to automate industrial safety-critical processes such as commercial diving, follow a clearly defined systematic process to assure the functional safety of these systems during their complete life cycle from concept to decommissioning.

Such a process is defined in the IEC61508 and IEC61511 standards (IEC=International Electrotechnical Commission).

IEC61508 – Serves as the basic standard and basis for safety standardisation. It covers all areas where electrical, electronic or PLC systems are used to realise safety-related protection functions.

IEC61508 covers “Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems (E/E/PE, or E/E/PES)”.

IEC61511 – There are sector-specific standards based on IEC 61508, such as IEC 61511 for the process industry or IEC 61513 for the nuclear industry. These sector standards are important for planners and operators of corresponding plants.

IEC61511 covers “Functional safety – Safety instrumented systems for the process industry sector”. Legislators / Regulators will refer to these standards for determining whether a reasonably practicable level of safety has been achieved. The IEC61508 standard is considered to be the basic generic standard intended to facilitate the development of sector standards. All other standards relating to functional safety have to comply with IEC61508 e.g. IEC62061, the Machinery Sector Standard.

Key features of IEC61508:

• Guidance on the use of Electrical, Electronic and Programmable Electronic Systems which perform safety functions
• Comprehensive approach involving concepts of “safety lifecycle” and all elements of a protective system
• Risk based approach leading to the determination of Safety Integrity Levels (SILs). Safety measures adopted are proportionate to the calculated risk
• Covers the Safety Related Loop “end to end”
• International standard allowing end users worldwide to operate in accordance with common standard providing confidence to system owners, users and regulators
• Systematic and technically sound approach
• Coherent based on commonly accepted underlying principles based on sound engineering logic and practise
• The standard was updated to edition 2 in April 2010. Significant changes included an emphasis on management of functional safety, requirements specifications, securityof automation systems and safety manuals.

It is essential that organisations managing the functional safety of automation systems have procedures and competent people in place to consistently meet the challenge throughout the lifecycle.