Wiki — standards,
legislation and terms

Yes, if it is to sit in a classified zone. Directive 2014/34/EU defines equipment as machines and devices capable of causing an explosion through their own sources of ignition, and that is expressly not limited to electrical equipment. The Danish regulation BEK no. 811 of 3 June 2022 covers, in so many words, all ignition sources, electrical as well as non-electrical. The Ex h marking on a pneumatic vibrator is precisely the marking for non-electrical protection.

Under Annex II Part B of Directive 1999/92/EC, zone 20 requires category 1, zone 21 category 1 or 2, and zone 22 category 1, 2 or 3. For dust the categories are written 1D, 2D and 3D. A silo interior holding combustible powder is typically zone 20 or 21, the outside typically zone 21 or 22.

It can cause cracking and reduced fatigue life if it is wrongly sized or wrongly placed. EN 1991-4 clause 3.4(9) states directly that where vibrators, air cannons or gyrating live bottoms form part of the silo installation, the alternating loads caused by them should be considered with respect to the limit state of fatigue. Cracking and reduced service life are documented. What is not documented is vibration equipment causing a silo to collapse.

It varies a great deal, and the difference is large enough to be a selection criterion in its own right. In the Flow Aids catalogue OLI states maximum levels of 125 dB(A) for the PS hammer, 105 for the PG air cannon, 100 for P, around 90 for S, OR and OT, 80 for K and F, and 76 for MVE. The Danish limit is a noise exposure of at most 85 dB(A). Where people work close to the silo, the choice of family is therefore not a matter of indifference.

Machinery Regulation (EU) 2023/1230 replaces Machinery Directive 2006/42/EC. The European Commission states that all machinery placed on the EU market before 20 January 2027 must comply with the Machinery Directive, and that the Regulation applies on a mandatory basis from 20 January 2027. EUR-Lex gives 19 January 2027 as the last day of validity of the Machinery Directive. There is no overlap period; the changeover is keyed to the moment the product is placed on the market.

Not always, and it is worth settling that first. ASTM D6128, the Jenike shear test, states itself that its primary application is the design of bins and hoppers to prevent flow stoppages. If the hopper is too shallow or the wall too rough, the answer lies in the geometry or the surface, not in a vibrator. And for a material prone to flushing, more vibration or more air can make the problem worse.