THE PURPOSE of both Intrinsic Safety (IS) and Flameproof to prevent a malfunction of electrical and electronic process control equipment from causing an explosion through the ignition of a gas atmosphere that may be present in the surrounding area. In both cases, the potential energy level is kept below the ignition level that is required to start the ignition process however; the use of Intrinsic Safety can offer significant savings, reliability and flexibility when evaluated to other hazardous area protection methods.
The advantages of using intrinsic safety as a protection method is that it is the only recognized procedure that is allowed to be used in Zone 0 as per IEC/SANS area classification system for hazardous areas. No other method like Flameproof, increased safety, non incendive methods or any of the many other methods of protection can be used in
Zone 0 except for double protection which however is highly impractical.
Intrinsic Safety manages the amount of energy available to a level well below that at which ignition can occur whereas Flameproof on the other hand contains the energy of any possible explosion within the enclosure and thus containing the possible ignition source. The net result is that Flameproof protection has a higher level of required maintenance and cost implications than an Intrinsically Safe System.
Examples of already certified products are: Radio systems, Cell phones and pagers, Intercoms, Ear muff communication systems, Multimeter's, and Miners Cap-lamps to name a few as well as various process instrumentation equipment etc.
We at Explolabs have the resources and expertise in both fields and offer our services to the Mining and Petro-chemical industry as your safety is our concern.
For further information on the above, please us a call and our friendly staff will assist you with your queries.
After having to sit through a tender meeting and listen to venders and the client arguing over what exactly the client required I felt so appalled at the volume of misconceptions that I had to express my understanding of explosion prevention. I hope you find it of value and that it wil clear rather than further deepening some of the chaos around explosion prevention. [ Continued ]
The second edition of ARP 0108 i.e. ARP 0108 Edition 1.1: 2007 was published in March 2007. The following are extracts from this document: “A.1 From the date of publication of this recommended practice (plus a six month phase-in period), all new EPA requires a certificate issued by an ATL. Such certification will normally be based on approved national standards (refer to column 2 of table A.1). However, certification in terms of the standards listed in column 3 of table A.1 may be used as the basis for issuing such a certificate (IA certificate).
No local testing will be required on equipment certified in terms of column 3, on condition that the ATL is provided with adequate evidence of recognized prior testing which demonstrates compliance with the applicable approved national standard.
Therefore, from September this year all imported Explosion Protected Apparatus (EPA) must be covered by an IA certificate (a type certificate issued by an ATL or local test laboratory like ourselves).
Initially, Explolabs worked together with existing product certification bodies to establish an Ex Mark Scheme. During 2003 the opportunity however arose to establish a new product certification body. CERTEX (Pty) Ltd was launched late in 2003 and is looking forward to issuing a number of marks in 2004!
CERTEX will operate close to the industries it serves by (a) transparent approval of marks by appointing member(s) from industry to our Board of Approval and (b) end user representation on our Advisory Committee.
Although CERTEX has a preferred-laboratory relationship with the two test laboratories in EXGROUP ie Explolabs and SALAB, test reports from other accredited laboratories are by no means excluded.
CERTEX will also form agreements to ensure access for its clients to other national and international certification marks. An agreement has been established with DQS to provide system certification.
With this step, the whole spectrum of testing and certification services is now on offer. We look forward to spend a productive year with you our clients. Please send through a request if more information is needed.
Part of the current revising of SANS 10108 involves the relocation of certification requirements in Recommended Practice (ARP) 0108, a closely related document controlled by the regulators. ARP 0108 defines the validity rules for Ex certificates, the most significant being that certificates have a finite lifetime and that re-certification must take place after a certain period (10 years has been proposed). As standards change, re-certification may necessitate design changes.
This approach has the following implications for manufacture and repair: New units produced during the validity period of the certificate will not be affected by changes in the standard. If these units are repaired (during or after the validity period), such repair work must be in accordance with the initially certified design or at least with the minimum requirements of the standard against which initial certification was done.
In principle, this means that a non-OEM repairer should be able to identify to which edition of a standard the equipment has been certified and that the minimum requirements of that edition apply. Practically, most repairers will tend to repair to the latest version of a standard, and they will only revert to the use of older editions used for certification in cases where expensive modifications are required. Examples that come to mind are the use of anti-static plastic motor fans, replacement of flameproof bushes with ones using certified polymeric insulating materials, and the change in maximum allowed temperature for Group I equipment (underground mines) from 200°C (T3) to 150°C in cases where coal dust may be present.
The new revision of SANS 10108 (Edition 5) together with the first edition of ARP 0108, should be published in the first half of 2004.
Technical Committee 31 of the International Electrotechnical Commission (IEC) and its subcommittees are responsible for explosion protection standards. A few of the current focus areas are:
A full report on the work of TC31 can be obtained from Explolabs or SAFA.
The following organizations are significant role players in the South African explosion protection industry:
The government:
The Department and Minerals and Energy and the Department of Labour issue legislation to enforce explosion protection in mines and plants where appropriate.
Testing laboratories and certification:
Explolabs and EPT (SABS Test House) are Ex testing laboratories .
Product certification bodies:
CERTEX and Global Conformity Services (SABS) operate Product Certification Schemes.
Standards publishing bodies:
Standards South Africa (nationally), IEC (electrical) and ISO (other), and CENELEC (European electrical) and CEN (European other) are major standards producing bodies.
Organization representing all interest groups:
The South African Flameproof Association (SAFA) includes plants and mines, equipment suppliers, legislators and testing laboratories.