The emitters are devices that control the exit of the water from the lateral pipes.
According to the flow they provide, they are divided into two groups:
-Emitters with low flow, less than 16 liters / hour. It includes emitters and emitting pipes or tapes.
-Emitters of high flow, between 16 and 200 liters / hour. It includes the diffusers and the micro-sprinklers.
An issuer must have the following characteristics:
-Little sensitive to obstruction.
-Little sensitive to pressure variations.
-It maintains its characteristics over time. It is not necessary that the issuer possess all these characteristics at once, but only those that are required for each specific case. For example, an emitter must be less sensitive to blockage when using fairly contaminated surface water, but this quality is not as necessary when using clean groundwater. On flat terrain no emitters are needed to compensate for pressure differences, but they are needed on undulating terrain.
Types of emitters:
Depending on the configuration of your duct, the drippers can be classified as follows:
– Long conduit. The microtube dropper consists of a tube of small diameter and great length. Its exponent of discharge varies from 0.75 to 1. Due to the disadvantages of its regime close to the laminar, the microtube is no longer used as a dropper, but as a driving element.
– Of labyrinth. The water travels a labyrinth path, which increases the turbulence of the flow (exponent of discharge between 0.45 and 0.55). It is not very sensitive to blockages and changes in pressure and temperature.
– Of hole. The water discharges through one or several holes of small diameter. The regime is turbulent (exponent of discharge close to 0.5). It is not very sensitive to variations in pressure and temperature, but is easily clogged due to the small diameter of the holes.
– Swirl. This emitter has a circular chamber where a whirlpool occurs, in whose center the emission point is located. Due to the additional load loss that originates, the diameter of the duct may be greater than in other emitters, reducing the risk of clogging. The exponent of discharge varies from 0.45 to 0.55, so they are few sensitive to pressure variations.
– Self-compensating. This emitter has a device that allows to vary the size of the duct in relation to the inlet pressure. The device is generally a flexible membrane (diaphragm) that deforms under the effect of pressure, limiting the flow rate. The self-compensating effect is achieved within a certain range of pressures, which must be indicated by the manufacturer.
The connection of the dropper to the pipeline can be done in two ways:
– Interlinea. It is installed between two cross sections of the lateral pipe. When the dropper is connected to polyethylene pipe, the maximum increase in diameter caused in the pipeline as a consequence of the dripper installation must be 13%.
– In derivation or on line. It is installed on the wall of the lateral pipe through a hole made with a punch. The manufacturer must supply the appropriate tool to ensure the tightness of the connection with each type of dropper.