Design of Sprinkler Irrigation System

The main task of irrigation system design is to provide design drawings and instructions. Based on practice, the following sections mainly focus on preparation work, how to complete the drawing design, and how to write instructions. These works have no clear boundaries in the actual proces

1. Feasibility report preparation

1. Background of the project: It mainly involves the basic situation of the project location, the possibility and necessity of constructing irrigation projects2. Project construction content: mainly including the selection of irrigation types, the areacovered by the project, the situation of supporting projects, and other arrangements for project construction

3. Investment estimation and fund backlog raising4. Benefit analysis:Mainlyincluding water-saving benefits, energy-saving benefits, repayment period, etc

2.Basic information for planning and design

1 Topographic dataThe terrain of the irrigation area to be designed is generally provided in a scalediagram, which is necessary for the layout of the irrigation system and the calclation of hydraulic losses in the system

2. Soil data

This section includes soil quality, field water capacity, infiltration capacity, depth of permafrost layer, etc. It is the basis for selecting nozzles, and the combined irrigation intensity of the selected nozzle should not exceed the infiltration capacity of the soil.

3. Meteorological data

This section is the basis for calculating crop water requirements and formulating irrigation systems, mainly including temperature, rainfall, wind speed and direction, evaporation, and other data. Wind speeds of 3-4 levels can cause a decrease in spraying uniformity, making it unsuitable for spraying operations

4. Crop information

Crop data mainly includes the types and distribution of crops planted in the irrigation area. In the design, adjustments to irrigation methods and irrigation source systems need to be made based on the habits of these plants

5. Water source information

The water source information includes the location of the water source, water pressure and flow, water quality, etc. This part is not only the basis for water balance calculation but also a main basis for selecting the type of pump and filter.

3 Water source engineering planning

1. Analysis of water supply from water sources

The content of water supply analysis varies depending on the type of water source. For water supply projects that use previous water conservancy projects (outlets), the main analysis is the inflow and inflow process. For river water extraction, the annual and monthly flow of the river needs to be analyzed. For groundwater (wells) extraction as the water source, the inflow and dynamic water level of the wells should be analyzed

2 Water balance calculation

The purpose of water balance calculation is to determine the scale of the project, mainly to determine the size of irrigation area A=1005QT/la

In the above equation, A is the sprinkler area, m

Q is the available water flow rate m3/H, T is the daily allowable irrigation time hLa is the designed daily sprinkler irrigation intensity mm/d. P is the irrigation water utilization coefficient (p can be taken as 0.9-0.95 when the wind has little impact and the pipeline is transporting water)

3. Determination of Reservoir Capacity

Many projects require the construction of reservoirs, and the volume of the reservoir needs to be determined based on the balance between incoming water and water consumption. Only considering the water balance, the minimum volume of the reservoir can be calculated using the following formula: V=KQ1-Q2. In the above equation, V is the volume of the reservoir, mh; Q1 is the water demand of plants, mh; Q2 is the water inflow, m%/h; T is the daily irrigation duration h; K is the safety factor, taking into account the losses of evaporation and leakage, K is taken as 1.1-1.2.

4. Selection of irrigators

The correct selection of irrigators is the first step towards the success of modern garden irrigation systems. Modern gardens mainly consist of lawns, flowers, shrubs, hedges, and trees. For different plants, we need to use different irrigators to splash them. Lingxing Irrigation recommends using sprinkler irrigation and micro spraying for lawns, micro spraying for flowers, liquid and spray irrigation for shrubs, drip and micro irrigation for hedges, and spring or drip irrigation for trees.

5. Layout principles of nozzle

The spacing between nozzles is generally 0.8 to 12 times its range (half line of spraying), and the area with higher wind force is arranged. The closer the spacing between nozzles, the lower the uniformity of wind force above level 3 to 4, making it unsuitable for spraying operations. Unless otherwise specified, the following arrangements refer to their range

There are two methods for arranging nozzles: square (including square rectangles) and triangular. The design layout is usually a combination of the two methods

1. Square layout, suitable for conditions where the plot is regular and the edges are at right angles. This form of design is simple and easy to achieve balanced flow of each branch pipe

2. The regular triangle layout is suitable for irregular land plots, or when the boundaries of the land plots are open, even if the spraying range exceeds some boundaries, the impact is not significant. This arrangement has strong wind resistance, and the spraying uniformity should be higher than that of a square, making it difficult to achieve a balanced flow of each branch pipe

Sometimes the shape of the plot is very complex, or there are obstacles in the plot, resulting in an irregular combination of nozzles. However, in most sprinkler systems, a square or equilateral triangle arrangement can be used as much as possible

Square

Circular 

6. Installation of nozzle

Junfeng Irrigation recommends paying attention to the installation of geographical sprinklers

1.After installation, the top of the nozzle should be 0-10mm below the ground level

2.The installation position of the nozzle around the lawn should not exceed 15cm from the boundary

3. It is recommended to use an autumn stand, which is very helpful for achieving points 1 and 2 mentioned above during installation, while also aligning the nozzle (verticality of the nozzle) and reducing external forces on the nozzle and pipeline

Damage will have benefits

7. Pipeline layout

one

In general, the division of rotational irrigation areas involves simultaneously opening all irrigators for irrigation, which incurs high requirements for pipeline costs and water volume. Therefore, common irrigation systems are divided into several irrigation areas, each of which is controlled by a separate valve.

The flow rate of each round of irrigation area should be as close as possible, and the types of nozzles used in the same round of irrigation area should be consistent as much as possible

2、 Layout of pipelines

Layout principles

1. The layout of the pipeline should shorten the total length

2. The layout of the pipeline should be combined with the surrounding conditions.

3. When there is a contour line, the main pipe should be arranged vertically. If it can only be arranged parallel to the contour line, it should be placed as high as possible on the contour line. The branch pipe should be parallel to the contour line position to facilitate the control of the head loss of the branch pipe. If it is not possible to arrange the branch pipe parallel to the contour line, the branch pipe should be used along the slope or at an oblique intersection with the contour line, and the layout of the branch pipe on the slope should be avoided as much as possible

4. The main layout forms include tree shaped, abundant shaped, fishbone shaped, circular layout, etc

8. Hydraulic calculation of pipeline network (determination of pipeline diameter)

Hydraulic loss is quite troublesome, and it is recommended to use table lookup or software calculation. Lingxing Irrigation recommends recording the economic flow of various commonly used specifications of pipelines in daily work and checking them at any time. Here is an introduction to the principles of calculation:

The determination of branch pipe diameter is based on the calculation of hydraulic loss along the branch pipe, which is the head loss along the pipeline during porous flow

The difference in working head between any two nozzles of the same police station is not greater than 20% of the designed working pressure of the nozzle (hereinafter referred to as: 20% pressure). In fact, this part of the calculation is relatively complex, and a pipe diameter needs to be set first for hydraulic loss calculation. When the result is greater than 20% pressure, a larger pipe diameter Kang Xin calculation needs to be selected. When the calculation result is less than 20% of the designed working pressure of the nozzle, Need to select a smaller pipe diameter calculation to choose the most economical pipe diameter

Determination of main pipe diameter

The minimum diameter of the main pipe can be simply determined by the formula

D=1000 (4Q/3600 * * V) 1/2=18.8 (Q/V) 1/2

The derivation formula for Q-AV, where A is the calculation of cross-sectional area, and D is the diameter of the main pipe in mm when selecting a pipeline larger than it in existing specifications

9. Select the device and draw a local installation diagram

 The purpose of the partial installation diagram (detailed drawing) is to guide the correct installation of equipment in the system. All products of Lingxing Guanzhang are marked with standard local installation rings, which can be directly used when in use

10. Compilation and organization of design specifications

The design manual mainly summarizes and explains the previous work strictly, and the writing of the design manual should include the following content

1. Basic information for planning and design

2. Basis and introduction of the selected equipment

Introduction to the

 3 designed systems

4. Inflation system

5. Material usage and investment budget

6 Construction suggestions and operation management construction, etc