1. How deep should the pipe be buried below the ground?
In the southern plain irrigation area, the principle is not to affect agricultural machinery or manual farming. At least 40cm below the ground, and conservatively 50-60cm. In some places in mountainous areas, the soil layer is very thin, so it can only be determined based on actual possibilities. There is a situation when installing sprinkler irrigation in Zhushan: if the pipe is buried underground, the bamboo roots and bamboo shoots will be cut off during the trenching process, and farmers are reluctant to do so. Another situation is to "reluctantly" bury the pipe underground, but it is easy to dig the pipe when digging bamboo shoots, so simply lay plastic pipes or iron pipes on the surface of the hillside. In the northern irrigation area, the pipe must be buried below the freezing line, and the burial depth must be more than 1 meter.
2. Can the pipe be used directly after installation?
No! After the pipeline is installed and the backfill is positioned, a water pressure test must be carried out first. The test pressure of high-density polyethylene plastic pipes should not be less than 1.7 times the design working pressure of the pipeline. If the design pressure of the pipeline is 0.6MPa (6 kg), the test pressure should be above 1MPa (10 kg), and the range of the pressure gauge should be 1.3-1.5 times the test pressure, that is, 1.6MPa (16 kg) is appropriate.
During the test, the pressure should be increased slowly, and the test pressure should be maintained for 10 minutes. The pipeline pressure drop should not exceed 0.05MPa (0.5 kg, i.e. 5 meters). The pipeline is qualified if there is no leakage or rupture. After the pressure test is qualified, the soil should be backfilled. The backfilling must be carried out on both sides of the pipeline at the same time, and there must be no stones with a diameter greater than 2.5cm in the surrounding backfill. Before installing the nozzle or drip irrigation pipe (belt), the pipeline must be flushed with water to flush out the mud and debris that fall into the pipeline to avoid blockage.
3. How to connect PE pipelines?
Polyethylene PE pipes are connected by hot-melt butt or hot-melt socket, and threaded connection or bonding is not allowed. The two connection forms should use special connection tools respectively, and open flame heating is not allowed.
(1) Hot-melt butt shall comply with the following provisions
Clamp the interface ends of the pipe and fittings on the butt welding machine, and wipe the interface with a clean cotton cloth.
Smooth the connection end face on the milling cutter so that the gap is not greater than 0.3mm.
Correct the corresponding parts to be connected so that they are on the same axis, and the misalignment should not be greater than 10% of the wall thickness.
Place the heating tool between the two connection end faces, so that the two parts to be connected are close to the heating tool until the entire periphery is evenly flanged.
Quickly pull out the heating tool and use uniform external force to make them fully contact to form a uniform flange.
(2) Hot-melt socket shall comply with the following provisions
Hot-melt socket is suitable for the connection of polyethylene pipes and fittings with a diameter of less than 125mm. For diameters greater than or equal to 63mm, a socket welding machine should be used. For diameters less than 63mm, manual socket welding can be used.
The connection end should be cut vertically and wiped with a clean cloth, the insertion depth should be marked, and the skin should be scraped off.
The outer surface of the socket and the inner surface of the socket should be heated with special tools.
After heating, quickly remove the heating tool, apply uniform external force to insert to the marked depth, keep the position unchanged during the setting time, and do not let the joint bear excessive stress within 10 minutes.
4. What should be paid attention to when installing vertical pipes and sprinklers?
The connection between the branch pipe and the vertical pipe, and the vertical pipe and the sprinkler should be sealed reliably. Concrete piers should be set up at the connection between the branch pipe and the vertical pipe to ensure that the vertical pipe is vertical and stable. The vertical pipe diameter should be greater than or equal to the nozzle interface size.
The sprinkler should be checked before installation. First, check whether the sprinkler model meets the design requirements. In practice, it is often encountered that the construction workers buy small sprinklers casually, but the range is not enough, resulting in leakage. The interface size of the field sprinkler sprinkler cannot be less than 20cm (commonly known as 3/4 inch or 6 points). Irrigation areas with pressure greater than 30 meters should use nozzles with a joint size of ≥ 25cm (commonly known as 1 inch).
Second, check the diameter of the main nozzle. The diameter of the main nozzle of the field nozzle should be ≥ 4mm, preferably 5-7mm.
Third, check whether the rotating part is flexible and whether the spring is rusted.
5. What are the requirements for the installation of the water pump unit?
First, the inlet of the water inlet pipe (or shower head) cannot be placed on the bottom of the water, but should be fixed in the middle or upper filter box of the water body to prevent the inhalation of silt and garbage, and avoid clogging of nozzles, micro-sprinklers, and drippers.
When installing the air inlet pipe, air leakage should be prevented. If the air inlet pipe leaks, water cannot be pumped.
A water pressure gauge should be installed on the water outlet pipe of the water pump to monitor whether the working head of the water pump is normal. The range of the water pressure gauge should be about 1.3 times the maximum head of the water pump, so that the water meter pointer swings in the middle of the dial under normal pressure. The water meter cannot be directly pressed on the main pipeline, but should be connected to a "snake" or a small switch to produce a damping effect to reduce the water pressure fluctuation and facilitate the water meter reading.
When using an electric motor, the grounding of the casing must meet the requirements, and a leakage protector must be installed in the switch box.
The centrifugal pump uses a packing seal, and the water droplets flowing out are used for heat dissipation and lubrication during operation. The dripping rate is preferably 10-20 drops per minute.
6. What are the requirements for the installation of fertilization equipment?
The fertilizer (drug) device should be installed in front of the filter, and the inlet and outlet water pipes should be firmly connected to the irrigation pipeline. If a hose is used, twisting and folding should be prevented.
For sprinkler and drip irrigation projects used in conjunction with human and animal drinking water, it is strictly forbidden to install fertilizer and drug devices on the head hub and human and animal drinking water pipelines.
7. How should metal valves and plastic pipes be connected?
Pipes with a diameter greater than 65 mm should be connected with metal flanges. The diameter of the flange connection pipe (metal) should be 2-3 mm larger than the inner diameter of the plastic pipe, and the length should not be less than 2 times the pipe diameter. One end should be processed into a serrated shape, and the other end should be firmly welded to one side of the flange.
After heating the plastic pipe end, put it on the pipe with serrated teeth in time and tighten it with a pipe clamp.
Pipes with a diameter less than 65 mm should be connected with threads and installed with a flexible joint.
Valves with a diameter greater than 65 mm should be installed on the base, and the base height should be 10-15 cm.
8. What are the precautions for drip irrigation?
(1) Be sure to install a filter. The water source must be filtered, usually with a 100-mesh nylon mesh or stainless steel mesh; or a 120-mesh laminated or mesh filter. This is the key to the normal operation of the drip irrigation system. The filter should be cleaned regularly; the tail end of the drip irrigation pipe should be opened and flushed regularly, generally once a month.
(2) Before fertilizing, turn on the switch of the area to be fertilized for drip irrigation. Then dissolve the fertilizer in the fertilizer pool and start fertilizing after 20 minutes of drip irrigation. The fertilization time for each area is about 30-60 minutes, and the fertilization speed and time are adjusted by the switch.
(3) After fertilization, the drip irrigation cannot be turned off immediately. Sufficient time should be ensured to flush the pipes. This is an important measure to prevent system blockage. The flushing time is related to the size of the irrigation area. Drip irrigation is generally 15-30 minutes to completely discharge the fertilizer liquid in the pipes. Otherwise, algae, moss, microorganisms, etc. will multiply in large numbers at the drippers and block the drippers.
(4) Choose fertilizers with good solubility.
(5) Appropriately adjust the amount of fertilizer. For users who use drip irrigation for the first time, the amount of fertilizer should be adjusted based on previous years, and then the fertilizer should be dripped using the "small amount and multiple times" method.
(6) Frequently go to the field to check for leaks, pipe blockages, pipe breaks, cracks, etc., and maintain the system in a timely manner.
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