PURPOSE:To suck ambient air when exhausting indoor air by forming a ventilation port to the front plate section of the hood, shaping a ventilating pipe body communicated with the port and communicating the hood with the outside air through the port and the pipe body. CONSTITUTION:The ventilation port 11 is formed at the front plate section 3 of the hood 1 and a plurality of plate sections 10, 10, 15, 15, which are easily punched, and pressed are formed at other positions, an opening 24 and a communicating port 25 are communicted through the punching of the plate sections, and the ventilating pipe body 21 is shaped. The ventilation port 11 is communicated with a natural suction port C formed to the upper section of an exhaust port B by the ventilating pipe body 21. When a blasting devie 16 is operated, an oil mist, etc. rising from a range not shown are discharged as an arrow D from the exhaust port B through suction ports 4, 17a, but the outside air is naturally sucked in as an arrow E through the ventilating pipe body 21, the communicating port 25 and the ventilation port 11 from the natural suction port C when the interior of a room is brought to approximately negative pressure at that time. Accordingly, a change into negative pressure of the interior of the room is prevented, and load applied to the ventilating device 16 can be reduced.
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