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Whether the level of atomization is good or not, the performance of the nozzle is very important

(Summary description)Among spraying equipment, whether it is a sprayer with a complicated structure, or a sprayer with an intuitive structure, its basic structural units include a liquid tank, a pressure pump, a liquid tube, a spray rod and a spray head.

Whether the level of atomization is good or not, the performance of the nozzle is very important

(Summary description)Among spraying equipment, whether it is a sprayer with a complicated structure, or a sprayer with an intuitive structure, its basic structural units include a liquid tank, a pressure pump, a liquid tube, a spray rod and a spray head.

Among spraying equipment, whether it is a sprayer with a complicated structure, or a sprayer with an intuitive structure, its basic structural units include a liquid tank, a pressure pump, a liquid tube, a spray rod and a spray head. The nozzle is the most critical component, which indirectly restricts the atomization level of the spray. Regardless of its shape, material or internal structure, it requires careful design and optical manufacturing. Depending on the type and performance of the nozzle, there are also exact techniques that need to be controlled during field spraying.

The role of the nozzle in the spray equipment includes: the amount of spraying, the uniformity of spraying, the coverage of the target, and the control of droplet drift.

1. Types and working principles of commonly used nozzles

1. Vortex nozzle: There is a vortex chamber outside the nozzle. The liquid medicine rushing from the highway is forced by hydraulic pressure to rotate around the vortex root in the vortex chamber. The centrifugal force generated pushes it to spin and spray out from the nozzle hole, and interact with air molecules. When they collide, they form a hollow or hollow cone-shaped fog. The center of the hollow cone is difficult to drop, and the edge is left. The opposite is true for solid cone fog. The size of the droplets is indirectly related to the pressure of the liquid medicine and the aperture of the nozzle. The pressure is small, the spray hole is large, and there are many fine mist droplets; the just sprayed droplets are small, and as they collide with air molecules all the way forward, the droplets gradually become larger.

At present, the Gongnong-16 type knapsack sprayer, which is the smallest in my country, basically uses hollow cone nozzles.

Although this type of knapsack sprayer has been changed from manual to electric in recent years, which solved the problem of high pressure and never stable, but because the hollow cone spray nozzle sprays the liquid on the target, it is in the shape of an empty circle. , The liquid medicine below is difficult, and the liquid medicine is left on the edge, and the distribution is very uneven. It is necessary to swing the nozzle left and right when spraying to make the droplets evenly cover the target. There is an indirect relationship between the speed of walking in the field and the coverage rate of the droplets on the target. Researcher Yuan Huizhu from the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences found through experiments that the faster the walking speed, the smaller the difference in fog drop coverage and the more uneven the coverage. Therefore, many farmers use the medicine to spray quickly, add the remaining medicine with little water, and walk quickly. The practice of only filling 1 bucket of water per acre does not seem to be able to ensure that the target can be covered with a sufficient amount of liquid medicine, which leads to good medicine. One of the reasons for the poor results.

2. Impact nozzle (high-pressure spray gun): It is changed to consist of nozzle, spray cap, spray rod and diffuser. The principle is that the pressure of more than 1500~2500 kPa rushes out from the nozzle in a cylindrical shape and collides with the air. As a result, a spray of medicine is formed, with a flow rate of 30 liters per minute and a minimum range of about 15 meters. By adjusting the expansion and contraction of the spray rod, the spray width and distance can also be controlled, and the spray rod is compressed to compress the space inside the spray gun, and the spraying of fine droplets becomes more and more, and the spray width increases and the distance decreases. In production, many fruit growers often never pay attention to adjusting the balance between poor pressure, spray range and atomization quality after spraying. This is the limit of the fierceness, slowness and the flow of liquid on the target and the lower limit. The effect is by no means perfect.

3. Fan-shaped nozzle: There are two kinds of slit type and impact type. There are two mutually perpendicular half-moon-shaped grooves on the outside of the slit nozzle. The liquid medicine is now divided into two liquid medicines in the inner half-moon-shaped groove. Under the restriction of the groove, the spray is fan-shaped, and the working pressure is relatively small, usually 150~200 kPa; the outer end of the nozzle of the impingement nozzle has a chemical liquid deflector structure, so that the sprayed droplets are at a large angle (130 Degree) fan-shaped expansion, the spraying angle is significantly smaller than the usual nozzles (60-90 degrees), but the working pressure is relatively large (40-100 kPa), and the droplets are also small. It is often used for spraying herbicides. No matter what kind of fan-shaped sprinklers, you must not swing the sprinklers left and right like hollow cone sprinklers when working in the field. They should be pushed back horizontally.

4. Mist spray nozzle: Different from the following nozzles that use hydraulic pressure as the driving force, this type of nozzle guides the liquid medicine into a strong air flow field, and the liquid medicine is collided into mist droplets by the high-speed airflow, and Pushed onto the target by the airflow. There are several types of mist spray nozzles, such as rotating blade type, remote type and airflow type. The formed droplets are all small, and because of the assistance of airflow, the droplets sprayed on the target can be more and more badly distributed on the leaf surface. The front and back of the crop canopy.

2. Operation and control of spray equipment

1. Choose the appropriate nozzle:

Fan-shaped fog nozzle: uniform droplet distribution, mainly used for spraying herbicides for soil treatment and stem and leaf treatment. It can also spray insecticides or fungicides for the prevention and control of plant diseases and insect pests at the seedling stage.

Cone mist nozzle: It can be used for the prevention and control of crop diseases and insects in the field, and nozzles with different apertures can be selected according to the control object.

Adjustable fog nozzle: it can be used in orchard or boom sprayer, according to the target and wind speed to adjust the nozzle's spray width and droplet size, etc.

The single nozzle is used in the late or late crop growth period.

Double spray nozzles are used for directional spraying on the top of the plants in the later stage.

When spraying with multiple nozzles, it is necessary to adjust the distance between the bad nozzles and the spray width in advance to avoid respray and miss spray.

2. Control walking speed according to nozzle type:

According to the nozzle type and operating pressure, it is necessary to understand the flow rate. It should be used to test the spraying flow rate of the spray equipment per minute by using a container with a measuring scale before spraying, and then calculate the appropriate pace or the walking speed of the machine. , The amount of spraying per unit area, etc.

When using spray guns in the orchard, connect the spray gun hose to the interface on the pipeline controller. Adjust the working pressure, in addition to check and adjust whether the spray gun fog shape has reached the perfect working state, after the adjustment, you can start the spraying operation.

3. Determine the direction according to the wind direction:

Spraying is most appropriate under breeze conditions. People's walking direction should be perpendicular to the wind direction. The angle between the wind direction and the direction must not be less than 45 degrees. The operation sequence should start from the leeward side of the entire plot. Never work against the wind.

The spraying route should be used as an alternate side spray. If you spray the second row after spraying the first row, you should walk between the second row and the third row, so as to prevent the liquid from sticking to the body. Poisoning accident. With the help of government affairs, swing the spray rod in front of you, so that people walk through the application area, and it is difficult to cause poisoning. When spraying several machines other than that, the trapezoid should be used to advance, and the person on the leeward side should spray first.

4. Adjust the distance between the bad nozzle and the target according to the type of equipment and the wind force:

The spray speed of the mist droplets from the nozzle is usually about 20m/s, depending on the size of the mist droplets, the speed will decay to zero after running about 20-60cm. However, in the production of spray equipment, there will be some devices that give impetus beyond the amount of droplets. According to the principle of force and reaction force, the closer the nozzle is to the target, the greater the proportion of the droplets rebounding and splashing. In addition, the diameter of the droplets just ejected from the nozzle is also small and cannot adhere to the target. When the wind is small, the thick droplets are easy to drift above the non-target. Therefore, when spraying in the field, there must be a suitable distance between the sprayer and the target according to the type of spraying equipment and the wind force.

Normally, for manual spraying equipment, the distance between the nozzle and the target is 30-50 cm,

Motorized spray equipment, the distance between the nozzle and the target is 40~80 cm. The less the pressure, the farther the distance, the lower the wind, the closer the distance;

In general, the nozzle is the core component of the spray equipment that guarantees the quality of spray. During production, it is not only necessary to select the appropriate spray equipment, but also to select and maintain the nozzle, and use the sprayer appropriately according to the type and working principle of the nozzle.

Zhuji Haihang Misting Equipment Co., Ltd.

No. 462, Zhongyang RD., Diankou Town, Zhuji city, Zhejiang Province, China


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