| 摘要 |
The adjustable diaphragm forms a variable discharge orifice (3) from a chamber maintained at a light positive pressure by a gas supply, which opens up fully when the chamber is purged to prevent it being over pressurized. The walls (1) of the sealed chamber (2) contains an orifice (3) made from a flexible diaphragm, which contains a series of radial slots emanating from a central hole. This diaphragm is clamped in position by a ring (4). When the chamber it kept slightly above atmosphere, the flaps of the diaphragm are closed and the gas exchange is about one volume per hour. On purging the chamber, at about 50 to 60 volumes per hour, the orifice opens to its full extent (e) to allow for the extra gas flow without over pressurizing the chamber
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