摘要 |
<p>A duct made of flexible material, comprising a plurality of spaced dispensers (14) and regulator valves. Each dispenser (14) is provided with two ports (18, 19), one for ground dispensing and the other one for over-the-crop dispensing; the ports are controlled by respective differential membrane valves (20, 21). The ports are supplied by separate system sections, one at low pressure and the other one at high pressure, which comprise respective pipes (130, 131) which are supplied by corresponding motorized pump units at low and high pressure respectively; the pipes (130, 131) are joined in a single duct (13) with side-by-side passages provided with a cross section shaped substantially like a figure-of-eight.</p> |