摘要 |
<p>In an evacuation pumping device with primary force pump(s) (1) and secondary suction pump(s) (2) in series, driven by first and second electric motors (1b, 2b) with speeds modifiable by an electronic control module (3), the module has controllers which, as pressure in the chamber to be evacuated reduces, progressively increase and decrease the secondary and primary pump speeds respectively according to respective laws of variation (B) and (A).</p> |