This question relates to the ATEX directive, which is the European regulation governing the design of products to be used in explosive atmospheres. In particular, I am asking about the part relating to non-electrical (i.e. mechanical) devices.
Does anyone have experience in applying non-electrical ATEX to products containing springs? If so, do you know of any good guidelines as to how to conduct the assessment?
I'm thinking that the main potential ignition source would be a mechanical spark, which could conceivably be generated if the spring was to fail. So, the question boils down to: how to assess whether this is a genuine concern or not?
One possible option would be to assume as a worst-case that all the stored energy in the spring is converted into heat in the spark, and compare that to the minimum energy needed to ignite the explosive mixture; however, my gut feeling is that would be very conservative.