| 摘要 |
<p>A system (10) for extracting samples from a stream in a conduit (12) utilizing a probe (14), placed in the stream and having a channel (18) for passing samples from the conduit stream. First and second pressure taps measure the pressure inside and outside the probe. A feedback signal, based on a pressure differential relative to the probe, is generated and controls a valve (68) regulating sample velocity flow through the probe channel, that bears a fixed proportion to the velocity of flow in the conduit. The constant of proportionality between flow velocities in the conduit and the probe may be 1.0, resulting in an isokinetic sampling condition.</p> |
