Can be used in Zone 20 zone 21 and Zone 22 dangerous places. Can be used in explosive or flammable dust atmosphere.

粉尘防爆照明应急两用灯，21区，22区危险场所。 含有爆炸性或可燃性粉尘环境。

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Outside of the silo and in the loading duct this condition occurs only occasionally, eg during filling and empty (zone 21).

外筒仓和在装货管道发生这种情况只是偶尔，在灌装和空(区21)如。

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Where, following an abnormal condition, the removal of dust accumulations or layers cannot be assured, then the area is to be classified zone 21.

如果不能保证排除可燃性粉尘堆积或粉尘层时，则应划分为21区。

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Alan Pardew's side have collected just seven points from their last ten games and now sit two places above the relegation zone on 21 points.

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Phillips also announced that this year's tournament, which runs from June 21 to July 4, will be a "World Cup-free zone", with football fans denied the chance to watch matches on the big screens at the All England Club.

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They say there is particular concern over the very long-lived northern low pressure zone of circumpolar winds, called a vortex, found at between 13 and 34 km (8 and 21 miles) above the Earth's surface.

BBC: By Environment Correspondent Alex Kirby