The ATEX Directive 94/9/EC uses two terms; “The Dossier” and “The Technical Documentation” but common usage is the term “The Technical File”
Whether the technical file is in support of EC-Type Examination in accordance with Annex III, Internal Control of Production in accordance with Annex VIII, or Unit Verification in accordance with Annex IX, the technical requirements are the same. The difference lies in who is responsible for acceptance of the validity of the file.
Historically, manufacturers of electrical equipment have been used to certification bodies, such as Baseefa, preparing the technical file for them. The file would consist of the certificate, plus the report on examinations and tests, plus the manufacturer’s drawings, which had usually been modified after discussion to show the relevant detail to demonstrate compliance with the standard. In contrast, the ATEX Directive presumes that the manufacturer will prepare the technical file which, for certain conformity modules, will then be validated by the Notified Body.
In practice, many manufacturers still rely on a significant input from their Notified Body. Most Notified Bodies, like Baseefa, will offer services on a voluntary basis (outside their formal appointment) to assist manufacturers prepare technical files, or to issue certificates where the market requires.
The best words to describe the purpose of a Technical File are given in Annex IX.
“The aim of the technical documentation is to enable conformity with the requirements of the Directive to be assessed and the design, manufacture and operation of the equipment or protective system to be understood.”
To this end, all three Annexes list six aspects to be included in the Technical File.
A General Description
This would include type identification and performance information, as well as an outline description that provided sufficient overview such that the particular equipment could be recognised, together with any specific interface details that might be necessary.
Design and manufacturing drawings, layouts, schedules, etc.
For a Technical File to have a life beyond just one single manufactured item, there is an art in preparing the necessary drawings, to ensure that they do not contain surplus information that might lead to unnecessary modifications to the Technical File throughout the life of the product. On the other hand, the drawings do need to contain everything that is relevant to compliance with the directive or the harmonised standards.
Descriptions and explanations necessary to understand the drawings and the operation of the product
Our experience at Baseefa is that this information is usually split between the general description, the drawings (often with copious notes) and the instruction document, rather than identified separately. Where the symbol “X” is used with the certificate number or technical file number (as required by EN 13463-1) there will be a need to explain why there are the particular Special Conditions for Safe Use that it refers to.
Lists of standards or other solutions to meet the EHSRs of the directive
The wording used in Annex III is “- a list of the standards referred to in Article 5, applied in full or in part, and descriptions of the solutions adopted to meet the essential requirements of the Directive where the standards referred to in Article 5 have not been applied;”
This clearly allows the use of solutions not in the harmonised standards, but does require a full description of each solution (and, by implication, the rationale for it achieving equivalent safety). The description of the solutions will often be incorporated with the result of the examinations.
Calculations and Examinations
This is the argued case for compliance with the EHSRs, either via harmonised standards or “other solutions”. For example, drawings might show tolerances but there is a need to demonstrate how the build up of tolerances and concentricities can affect rotational clearances if they are relevant to the protection. Many of the requirements in the standards can be fulfilled without a test and there needs to be a record of that fulfilment. A dimensional measurement on a sample is not usually regarded as a test.
Test Results
Although calculation and examination will provide most evidence of compliance, there are some requirements which can only be demonstrably met by conducting tests on sample equipment, for example, temperature rises or deformation after impact.
The Ignition Hazard Assessment required by EN 13463-1 is an organised method of identifying where and how protection is required. As Baseefa, we were responsible for drafting the simple example of the mechanical parts of a solenoid valve that appears in Annex B to the standard. We were concerned that the other example, that of a complicated conveyor belt installation, might overface those who had comparatively simple equipment. Most equipment will fit between the two extremes.
The process is not difficult but it does require the ability to ask questions and state the obvious. For example, designers of fans would not normally think of the impellor being damaged and causing frictional ignition in normal operation. None-the-less, the obvious should be stated. A damaged impellor is an ignition hazard. The protection is probably either to use design rules (with a stated safety factor) for its strength or to do an overspeed test. This can be built up by adding a vibration detector (EN 13463-6, Protection by control of ignition sources) to increase the Category of the fan.
The Ignition Hazard Assessment, whilst being probably the single most important part of the process, does not have an obvious position within the defined contents of the technical file. For this reason, most technical files are not broken into sections in the way envisaged by the writers of the directive.
There is a curious difference in the marking requirements between the directive and the two basic standards. The directive does not require a certificate number or any other like number to be marked. EN 50014 requires that electrical equipment shall be marked with a certificate number. (EN 50021 for Category 3G requires a certificate number where applicable.) EN 13463-1 requires either a certificate number or a technical file number.
Unlike other directives where there may be considered to be an allowance to assemble the technical file after the event, ATEX clearly requires the technical file to be a fixed and identifiable document, available at the time of despatch of the equipment. For the intermediate situation where the manufacturer of Category 2 non-electrical equipment has to deposit the file with a Notified Body, it is, in effect, giving the file the same traceability as a certification package.
The relationship between the technical file and the EC Declaration of Conformity has a time element in it. The technical file, like a certificate, is a statement that was true on the day it was made. The Declaration of Conformity is made anew, each time a piece of equipment is made and sold. If the technical requirements of the directive have changed (for example by amendment or re-issue of a harmonised standard) it is incumbent on the manufacturer to check that the existing technical file still holds good as a basis for a current Declaration of Conformity. In this respect, Notified Bodies should be up to date on all standards work, and be able to provide advice.
For more information, contact Ron Sinclair on 01298 766607 or ron.sinclair@baseefa.com
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