1. Field of the Invention
Embodiments of the invention described herein pertain to the field of irrigation apparatus. More particularly, but not by way of limitation, one or more embodiments of the invention enable an internally pressure compensated non-clogging drip emitter.
2. Description of the Related Art
There are multiple types of irrigation drippers. Simple drippers exist that are inserted serially along pipe, either by forcing a hole into the pipe and placing the dripper on the outside of the pipe, or by cutting the pipe and inserting the dripper in line with the pipe. These systems require great amounts of labor when providing a watering system for a large agricultural area for example.
Other types of drippers include drip emitters that are inserted into pipe, generally when the pipe is extruded. This type of dripper system enables rapid deployment of great lengths of pipe, i.e., dripper line, wherein the drippers may be ordered for certain distances along the pipe for example. There are many types of emitters that may be inserted into the pipe including non-pressure compensated drippers that may provide more flow in lower areas of an agricultural drip irrigated area.
Other types of emitters include pressure compensated drip emitters that provide compensated drip volumes regardless of the depth or height or pressure difference in an agricultural drip irrigated area. In addition, other features of drip emitters include “non-drain” capabilities that retain water in the pipe when the pressure in the pipe falls beneath a threshold. Non-drain drip emitters generally include a valve that does not allow for water to flow from the drip emitter until a certain pressure difference is reached with respect to internal pipe pressure versus atmospheric pressure. Such a valve may or may not include a check valve for instance. Check valves allow flow in only one direction, for example when the internal water pressure in the pipe exceeds a pressure difference with respect to atmospheric pressure. Non-drain drippers without check valves are failing after 1 year in the field and the industry is moving towards anti-siphon valve based drip emitters that inhibit backflow of air or water or mud into the pipe under negative pressure, thus inhibiting any outflow from lower elevation emitters as well as the higher elevation emitters inhibit backflow and hence prevent siphoning. Anti-siphon valves are implementations of check valves that have also generally been placed before the labyrinth section to keep water and air from entering the pipe.
Check valves heretofore have usually been placed before labyrinth sections within drip emitters. This leaves the labyrinth exposed to air and potential clogs. This pre-labyrinth check valve placement is problematic in that air can enter the labyrinth and cause a clog in the labyrinth section. When air enters the labyrinth, the water evaporates. When air mixes with water that has suspended iron, the suspended iron can solidify and cause a clog. In addition, mud can enter the labyrinth with no valve to prevent backflow into the drip emitter.
The filter on cylindrical drippers fitted with non-drain or anti-siphon mechanisms before the labyrinth have traditionally been small as they must be smaller than the size of the diaphragm used to create the valve mechanism. A small filter can easily clog. Hence, not only do current non-drain and anti-siphon drip emitters clog due to problems related to material other than water entering the labyrinth, but they also clog due to the small size of the filters that have been used before the labyrinth in the flow path of water for example.
Pipes fitted with non-drain elements are very difficult to evacuate as they do not allow air into the pipe through the dip emitters when under a vacuum or low pressure. When filled with water, an irrigation pipe is very heavy and is not able to be rolled up for example when certain types of crops have been harvested and the pipe is to be stored.
Currently known drip emitters may clog over time for a variety of other reasons as well. Many of the reasons for clogging in currently known drip emitters are related to or a result of non-turbulent pathways, i.e., laminar transfer zones or any path of water flow that is straight enough to allow sediment to settle. For example, between the inner portion of the emitter to the pool area of the emitter, if a transfer zone is formed as a straight line, for example across a mold joint, sediment accumulates in the non-turbulent zone over time and eventually forms a clog as sediment settles. In addition, drip emitters include a filter tend to clog when the emitter is rotated so as to locate the filter downward wherein sediment settles, which clogs the filter. In addition, emitters that utilize only one hole may clog if covered by soil for a rock for example. In these situations, a second hole is not utilized to provide a level of redundancy.
In addition, pressure compensated emitters that utilize a two shot injection mold exist which provide a pressure compensation element that compensates for pressure with a membrane that directly deforms against extruded pipe. The problem with this type of emitter is that the pipe quality, diameter, and internal surface finish can vary along with pipe from day to day and from pipe manufacturer to pipe manufacturer. Hence, the performance of the pressure compensation element depends greatly on a secondary apparatus, i.e., the pipe and process of manufacture thereof. For at least the limitations described above there is a need for an internally pressure compensated non-clogging drip emitter.