| 摘要 |
<p>For the protection of a submersible ballast pump (4) of the type comprising a pump head (5), a riser pipe (7) projecting upwards therefrom having a pump drive shaft, and a top piece (6) with a motor, arranged in conjunction with the pump drive shaft, against freezing when not in operation, air is caused to circulate in a circulation cycle (12, 14, 15, 13) that includes the riser pipe (7).</p> |
