| 摘要 |
A pair of coaxial tubes (12, 12', 13, 13') are provided for dispensing liquid (19). The inner tube (12, 12') is at least partially gas permeable and fluid flows through it, in use. The outer tube (13, 13') surrounds the inner tube (12, 12') and is radially spaced therefrom. A sealed volume is formed between the two tubes (12, 12', 13, 13').
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