Internal Zoning On Elevators
To say a region is Zone 20, it is necessary that a dust explosive atmosphere is present close to 100% of time. Has your machine any potential source of ignition inside? This is the key point to safety. ■
Re: Internal Atex Zone On Elevators & Conveyors
Seeking guidance from a UK notified body, I hope they didn't charge you too much for too little in return!
Always worth remembering that UK notified bodies are commercial organisations, i.e. they are in business to make money. Additionally some are ex civil servants and as we all know civil servants are trained not to take responsibility and so couch responses in vague terms, or refer to other instructions/documents so avoiding actually making a decision.
Aside, I witnessed tests with a mobile test unit on MBM at a government controlled MBM site. After cleaning off the MBM the operator asked the official if the cleaning was sufficient only to get the reply "the regulations say all MBM must be removed prior to leaving the site". More cleaning and a second question resulted in exactly the same reply. Couldn't expect anything else really could you!
In the case of your notified bodies they probably relied on Reference to BS EN 61241-10 where appendix A includes reference to a screw conveyor with the statement "The interior of the ...... screw conveyor will contain dust clouds frequently and for long periods and are, therefore classified zone 20". (And there was me thinking it had to be an explosive concentration of dust. My house always contains dust clouds but at concentrations that will never explode!!)
So there you have it, the consultants answer that absolves them of all responsibility but allows them to take your money.
It's also worth remembering that different notified bodies may well give you different responses. This was raised at the end of the I.Mech.E. seminar "ATEX - Clarified & Updated" to a panel of those who had presented papers. The response was quite clear, it's not an ideal situation but yes this can happen! At least that answer was clear, the answers to other questions left me and quite a few others more confused than when we started. ■
Internal ATEX Zone on Elevators & Conveyors
We have spoken to several notified bodies in the UK and they all seem to confirm that the internal zone of bucket elevators, chain conveyors and U shaped trough screw conveyors should be Zone 20 if handling explosive dusts. However no manufacturers seem to certify their conveyors and elevators to Zone 20 internally.
Has anyone certified elevators and in particular chain conveyors & screw conveyors for the internal zone?
Ian ■