| 摘要 |
A pump head (4) has a casing (10, 20) containing an electric motor (15, 16) driving impeller means (31) for moving liquid upwardly of a pipe stack by which the pump head is suspended in the liquid. Cooling of the motor is improved by causing pumped liquid leaking between sealing rings (40 - 42) to flow through a helical tube (51) within the casing (10) and stator (16). |
