| 摘要 |
<p>The invention provides that a pumping unit can arrange to evert tubular members (26) into and along underground passageways (12). The pump unit is located at ground level and comprises a first section defining a sphincter valve (33), and a second section defining a pressure chamber (16). The sphincter valve is used to control the infeed of the tube and also to provide a seal of a pressure chamber. The pressure chamber is partially filled with water and is pressurised above the water with air from a supply (92) which also supplies the sphincter valve section. The two sections can readily be uncoupled by collapsing of the sphincter valve and the sphincter valve serves to seal the lower section in use. The upper side of the sphincter valve section is open to atmosphere and forms the infeed aperture for the tube.</p> |
