Drip level irrigation

Claim 1

An elongated dripper unit including at least one elongated enclosure having walls disposed generally parallel to the longitudinal axis thereof and being sealed at either end thereof, each enclosure comprising: a liquid inlet; a liquid outlet; at least one longitudinal partition disposed in said enclosure so as to divide said enclosure into at least two sub-enclosures; a plurality of lateral partitions disposed in relative spaced relationship with respect to each other, each lateral partition extending across one of said sub-enclosures thereby to divide each of said sub-enclosures into a plurality of cells including an input cell communicating with said liquid inlet, an output cell communicating with said liquid outlet and a plurality of intermediate cells; a plurality of liquid communication apertures of reduced diameter formed in said at least one longitudinal partition intermediate said lateral partitions, said apertures and said lateral partitions being arranged so as to permit sequential liquid communication from said input cell through said intermediate cells and to said output cell and defining a liquid flow path including a plurality of abrupt direction changes, the available cross-sectional liquid flow capacity of said apertures being substantially less than that of said cells, said liquid flow path thereby creating a negative liquid pressure gradient between said liquid inlet and said liquid outlet.