Hi. I am trying to purchase a multichannel portable gas monitor for pre/ use entry into grain silo's for cleaning. Having looked at two commonly used monitors, I find that the ATEX certificates only state G for gas. One company could only offer a fixed head for D. (Zone 21 BTW). Any one come across this issue? and if so, how did you manage to resolve? Maybe I am just unlucky with my choice for monitor? Thanks in anticipation

Hi imwaldra, My concern is that the internals of the silos are Zone 21 and the ATEX standard for equipment to be used in such as Zone states that it must be D. Irrespective of what gas is tested, the equipment ATEX should be compliant?

You need to understand why it is certified Zone 1 - I'm pretty certain it's for dust. If so, a gas detector adds no value. To be explosive the dust concentration in air has to be well above the level that causes breathing issues. So there normally isn't anyone around in such silos as they are filled, and the resulting dust cloud could be ignited by an elecrtic spark if non-ATEX equipment was used.

Everyone has made good points. It isn't my area of expertise, but before entering this confined space I would want to be assured that the atmosphere was safe to breathe. I know, for instance, that a steel container that is sealed for a long time will contain air that has too little oxygen for us to survive. The steel reacts with oxygen. Also if there are traces of organic matter left in the silo, I would be asking whether they could be fermenting; this would also alter the balance of gases in the atmosphere. Can they not be ventilated before entry?

Hey everyone. Many thanks for all your input to this. I am purchasing a gas monitor which is for the entire site wide use. I wanted to assure myself that the one chosen was suitable to use inside a Zone 21. I have considered all points from my RA (entrapment) etc so was only concerned about using the detector inside the silo. Alfaserv- I did contact manufacturer (make bright orange monitors..) who said "You are correct, our portable gas detectors are certified for Atex hazardous Gas zones, eg zones 1 and 2, not for dust zones" They then went on to say that some fixed head detectors were available for use in dust hazardous zones. I know I am talking about a well controlled risk here (for instance, no grain present, vent if dusty) but with my worst case scenario head on, things go bang (yes, I know, very low risk) how would I (we ) stand? However, your pointer to ACOP L138 para 138 is perhaps my way forward. I can demonstrate risks controlled by other methods as stated. Thank you