The irrigator is an important equipment element in the drip irrigation system, which guarantees the realization of drip irrigation. The quality of the dripper directly affects the quality of irrigation and the quantity required is quite large. There are many types of irrigators, according to the structure and outflow form of the irrigator, the irrigator is usually divided into two categories: dripper and drip irrigation pipe.
1. Dripper
A device that turns the pressure water flow in the capillary into a droplet or thin flow through a flow channel or orifice is called a dripper. There are many ways to classify drippers, and there are generally 3 categories.
A: The connection method between the dripper and the tube.
- Top-pipe dripper (vertical): The structure is basically the same as the inter-tube dripper, except that the other end is closed, and the threaded core can be screwed out to flush or adjust the flow. The long thread flow rate of 7.5 L/h. Short threads flow rates up to 9.5 L/h.
- Intertubular dripper (horizontal): The width of the runner is 0.75~0.9 mm, the length is 5060 cm, and the rated effluent flow is 2~3 L/h at 1 standard atmospheric pressure.
- Built-in dripper spiral dripper): The dripper is rolled into a spiral shape by a polypropylene tube with a diameter of 1mm, also known as a hair dripper, its working pressure is 0.7 kg/cm’, and the flow rate is 0.9~9.0L/h. Change the number of spirals turns to adjust the flow.
B: Dripper flow rate.
Divided into turbulent drippers and laminar flow drippers (porous capillaries, double-lumen tubes, microtubules).
C: Pressure compensation performance.
Drippers can be divided into two types: non-pressure compensation drippers and pressure compensation drippers.
- The pressure-compensated dripper uses the effect of water flow pressure on the elastomer in the dripper to change the shape of the flow channel (or orifice) or change the area of the water section. That is, when the pressure decreases, the area of the water section is increased. When the pressure increases, the area of the water section is reduced. This automatically keeps the drip flow within a small range of variations.
- The non-pressure compensated dripper uses a fixed water flow channel in the dripper to dissipate energy, and its flow increases with the increase of pressure. Non-pressure compensation drippers can be divided into the following types according to their energy dissipation principle: long-flow drippers (such as plastic microtube drippers, threaded drippers, maze drippers, etc.), orifice drippers, and adjustable drippers.
2. The drip pipe forms the dripper and the tube into a whole, and the tube has the function of distributing water and dripping water.
The diameter of the drip irrigation pipe is between 8~40 mm, the most used are 16 mm and 20 mm, the thickness of the drip irrigation tube is 0.15~2 m, and the use of less than 1 mm is the largest. Drip irrigation pipes are divided into two types: non-pressure compensated and pressure compensated. There are two main types of drip irrigation tubes cylindrical drippers and patch drippers.
Compared with drip tape, drip pipe has a longer life and a more expensive price. Compared with the dripper, the price is lower and the life is shorter, but the installation is convenient.
The advantage of drip tape is that the dripper is formed by injection, has high precision, small deviation, thin pipe wall, is low cost, easy to transport and lay.
- Disposable drip tape should be used for annual field crops.
- Perennial plants, such as trees, tea, etc., generally use drip pipes.
- Small-diameter drip pipe or drip tape should be used for protected areas.
- The terrain is flat and the capillary laying is short, as far as possible, a non-pressure compensated dripper is used, otherwise, it is recommended to use a pressure-compensated dripper.
- The flow rate of drip pipes or drip strips depends mainly on the terrain and soil texture. For plots with a heavy texture or slopes, it is best to choose a flow rate < 1.5 L/h. The heavier the texture and the greater the slope, the smaller the flow rate.
- Terraces with a lighter texture can be selected with a flow rate of around 2 L/h. If the economic forest has more water at a time, if planted along the contour line, you can choose a drip irrigation pipe with a pipe diameter of 20 mm and a flow rate of more than 3.0L/h, and you can also distribute a dripper with a larger flow rate according to your needs.
3. Overall, the irrigator design is roughly divided into 4 steps.
- According to the terrain and soil conditions, select the type of irrigator that can best meet the needs of the humid area.
- Choose the specific irrigator that meets the required flow rate, spacing, and other planning considerations.
- Determine the average flow rate and pressure head of the required irrigator.
- Determine the allowable pressure head change in the irrigation unit cell to achieve the ideal irrigation uniformity.
