| 摘要 |
A method of and apparatus for making double-walled thermal protective devices is disclosed in which two layers of thermoplastic material (10) joined together along at least one longitudinally extending edge are fed from a roll (11) by feeding rollers (12) through a heat sealing station (14) which forms transversely extending seal lines (22) to create a plurality of transversely extending compartments (24, 124) which are adapted to be filled with water. The heat-sealed layers are then cut transversely by cutting apparatus (18) to create individual lengths (20, 120) of a thermal protective device. The individual lengths (20) may be formed into a tubular thermal protective device (50) by sealing together the ends (28) of the device. Alternatively, the individual lengths (20, 120) may be used as an elongate thermal protective device for a row of plants, with the device incorporating a hose (140) inserted in a longitudinally extending gap (127) between the layers (111, 121) for filling the compartments with water.
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