Variable porosity irrigation pipe
AssigneeDasurat Enterprises PTE Ltd.
InventorJames W. Mason
Life of this patent
Estimating the term…
Abstract
Porous pipe having a porosity which varies continuously and controllably with length is produced by extruding a mixture of particles of prevulcanized elastomer such as reclaimed crumb rubber and a thermoplastic binder such as polyethylene with all parameters controlled except for die temperature of pull-off rate. By gradually varying temperature or pull-off rate during extrusion, the porosity of the pipe gradually changes. The leak rate can be controlled in a manner to produce a length of porous pipe in which the leak rate is constant as the pressure drops over the length of the pipe.
Claims17
An irrigation pipe comprising:
- a length of porous, flexible pipe having an inlet and an outlet end;
- said pipe having a wall formed of a major portion of vulcanized elastomer particles dispersed in a minor portion of thermoplastic resin binder, said wall containing a continuous pattern of pores extending from the inside surface to the outside surface;
- the porosity of the length of pipe gradually and controllably increases from a first inlet end to a second outlet end of the length of pipe such that the leak rate is substantially constant throughout the length of the pipe as the pressure drops from the inlet end to the outlet end.
A method of producing an irrigation pipe having a porosity that gradually and continuously changes with length comprising the steps of:
- extruding from an unvented extruder through an extruder die a mixture of a major portion of elastomeric particles and a minor portion of thermoplastic binder having a moisture content below 5 percent by weight at a temperature above the melting temperature of the binder in the range between 320.degree. F. and 400.degree. F.;
- and
- constantly varying the temperature of the extruder die or the speed of pull-off of pipe from the extruder die as the pipe is extruded to gradually vary the porosity along the length of the pipe.
Dependencies are inferred from the claim text.