Nozzles play a crucial role in various industries by transforming fluids into spray patterns. They can be categorized into single-fluid and double-fluid types, each with its own design and functionality.
Single-fluid nozzles typically feature a nozzle hole and a fluid inlet to disperse fluid into different spray patterns. On the other hand, double-fluid nozzles require two distinct fluids to achieve a wider range of spray effects through their combination.
Spray patterns are commonly classified into five types: fan, hollow cone, solid cone, spiral spray, and cylindrical spray. Each pattern has specific applications, advantages, and disadvantages, catering to different spraying requirements.
This article aims to provide an introduction to nozzle fundamentals, including spraying principles, benefits, drawbacks, and application
areas. By offering insightful perspectives, we strive to educate readers on the principles and selection criteria for nozzles. Whether used in industrial manufacturing, agricultural irrigation, or air cleaning, this information serves as a valuable reference for users in various application scenarios.
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Outline of this Article
● What is a spray nozzle?
● The nozzle is divided into single-fluid nozzles and two-fluid nozzles.
● About various spray patterns
● Principles, applications, pros, and cons of common spray nozzles
>Principles, applications, pros, and cons of flat fan spray nozzles
>Principles, applications, pros, and cons of hollow cone spray nozzles
>Principles, applications, pros, and cons of full cone spray nozzles
>Principles, applications, pros, and cons of flood type spray nozzles
>Principles, applications, pros, and cons of spiral nozzles
>Principles, applications, pros, and cons of two-fluid spray nozzles
● Epilogue
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What is a spray nozzle?
-spray nozzle-
A nozzle is a device that accelerates a fluid and increases its kinetic energy. It typically consists of a narrow passage and an expanding section. In the narrow passage, the fluid is restricted, causing an increase in velocity, while in the expanding section, the fluid is expanded, causing further velocity increase. Nozzles can be used in many different applications such as rocket engines, jet engines, water pipes, flame throwers and more. [1]
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The nozzle is divided into single-fluid nozzles and two-fluid nozzles.
-Schematic diagram of the principle division of one-fluid and two-fluid nozzles-
One-fluid nozzles and two-fluid nozzles, also referred to as single-fluid and two-fluid nozzles, are commonly encountered nozzle types. A one-fluid nozzle typically consists of a channel through which liquid flows to generate a single jet. This kind of nozzle finds applications in tasks such as water mist spraying, coating, cleaning, and more. It operates by pressurizing the liquid solely using a pump to achieve the desired pressure and then expelling it through the nozzle. In comparison to two-fluid nozzles, one-fluid nozzles produce coarser spray particle sizes on average and lack adjustability in this regard.
Two-fluid nozzles are comprised of two channels: one for gas and another for liquid. As both gas and liquid flow through these channels, they combine within the nozzle, resulting in a finer and more consistent jet. These nozzles find wide applications in tasks like spraying chemicals, paints, fuels, and more. Inside the two-fluid nozzle, the gas and liquid undergo thorough mixing, enabling enhanced control over particle size and spray uniformity. However, when employing a chemical solution containing reactive substances in two-fluid spraying, there is a possibility of oxidation reactions occurring with the surrounding air, potentially accelerating the degradation rate of the chemical solution. Hence, it is crucial to exercise judgement and exercise caution regarding the amount of chemical solution used based on experience.
The primary distinction between a one-fluid nozzle and a two-fluid nozzle lies in their internal structure. One-fluid nozzles possess a single flow path, whereas two-fluid nozzles feature two separate flow paths for gas and liquid. This disparity impacts the functionality and application of each type. As the two-fluid nozzle must account for airtightness and liquid tightness, it commonly employs a multi-piece design, thereby resulting in higher costs compared to one-fluid nozzles. [2] [3]
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About various spray patterns
-Schematic diagram of 3 kinds of spray shapes -
The spray pattern of a nozzle refers to the shape of the liquid released from the pressurized source. It is an important factor as it determines the uniformity of the liquid coating, which is crucial for many applications, especially in processes such as coating, cleaning, and spraying. A good spray pattern ensures an even distribution of the coating, leading to better corrosion protection and quality.
Different nozzles can produce various spray patterns, including cone-shaped, fan-shaped, circular, and straight-line patterns, among others. Each spray pattern has its own suitable applications and characteristics. For example, cone-shaped spray patterns are commonly used in wide-spread spraying applications, as they can evenly distribute the liquid over a relatively large area. Fan-shaped spray patterns are suitable for situations where even spraying in a specific direction is required, such as cleaning and cooling applications. Circular spray patterns are often used when a surface needs to be uniformly covered, such as in coating and painting applications. Straight-line patterns are typically used for precise point spraying, such as in localized painting or fine mist applications.
Understanding different spray patterns and their suitable applications can help us choose the appropriate nozzle to achieve the desired effect. In our applications, we should select the nozzle based on specific needs and process requirements to ensure that the liquid is evenly sprayed onto the target surface, thus achieving optimal results. [4]
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Principles, applications, pros, and cons of common spray nozzles
- Principles, applications, pros, and cons of flat fan spray nozzles
Principles
A flat fan nozzle is a common type of nozzle that works by passing liquid through a channel and then spraying it out of a fan-shaped hole. The design of the fan-shaped hole causes the liquid to be squeezed when it passes through the nozzle. Since the pressure cannot be released, the liquid flows to both sides respectively, making the shape of the liquid spray like a fan. Flat fan nozzles are suitable for cleaning, degreasing, cooling and other applications. [5]
Pros
- Easy access and selection of highly versatile spray components
- Simple structure with basic components for straightforward nozzle control
- Resistant to clogging, reducing maintenance requirements
- Offers superior impact compared to other nozzle types
Cons
The spray pattern of a fan-shaped nozzle resembles a narrow column. Unlike the circular spray pattern of a solid cone nozzle, it requires a larger number of nozzles to cover the same area without movement. As a result, the spray efficiency of a fan-shaped nozzle is not as high as that of other types of nozzles. The number of nozzles needed for adequate coverage can be significant.
Applications
Fan-shaped nozzles are commonly used in cleaning applications, such as car washing machines. These machines utilize back-and-forth motion, spraying high-pressure water and detergent onto the car body, and employing electric brushes to remove dirt. The majority of car washing machines utilize clip-shaped nozzles for high-pressure water spraying. Fan-shaped nozzles offer affordability, cost-effective installation, and low maintenance. Although their spray coverage may not be as efficient as solid cone nozzles, the car washing machine's front and rear operations compensate for this drawback, ensuring thorough cleaning with high-pressure water. Therefore, in industries where nozzle consumption is high, price considerations and other limitations can be mitigated through equipment design or alternative technologies while still achieving the desired spraying results. (More)
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- Principles, applications, pros, and cons of hollow cone spray nozzles
Principles
Hollow cone nozzles, also known as vortex spray nozzles, operate on the principle of creating a tornado-like vortex flow within their cavity structure. When liquid enters the hollow cone nozzle's cavity, it is directed to spray outward through the curved surface design of the nozzle opening, forming a hollow cone spray pattern. Typically, the spray distribution of the hollow cone nozzle is concentrated at the outer ring position, but adjustments to the nozzle structure can enable liquid distribution in the middle area as well. This nozzle is commonly used for hollow cone spraying, producing spray particle sizes similar to or even smaller than those of fan sprays.
One key characteristic of the hollow cone nozzle is that the liquid flows against the inner surface of the nozzle, making the inner wall susceptible to wear. However, compared to solid cone nozzles, hollow cone nozzles have a larger channel diameter, which reduces the likelihood of blockages caused by foreign matter. Another advantage is that hollow cone nozzles do not require a compressor or compressed air, allowing them to achieve fine atomization effects. This feature is advantageous in applications where a compressor is not needed and a fine mist is desired, simplifying installation and saving energy and costs.
Pros
- Capable of generating jets with smaller particle sizes, even at low pressure.
- Ensures uniform spray distribution.
- Features a simple flow channel structure with a wide passage diameter for foreign matter, effectively preventing clogging caused by debris.
Cons
- May experience uneven spray patterns when used under high pressure.
- The spray efficiency is concentrated on the periphery, leaving the center area uncovered.
Applications
In the steel industry's washing towers, dust-laden gas enters from the lower part of the tower, while a hollow conical nozzle is installed above to spray water mist. This creates a flow contact between the water mist and the dust-laden gas. Within the washing tower, dust is collected through a combination of inertial collision between the water film on the filler surface and the gas, as well as diffusion and attachment of the dust particles. The liquid used in the iron and steel industry processes often contains impurities. The hollow cone nozzle, with its simple flow channel structure, offers advantages such as a wide diameter that resists clogging. Furthermore, it can provide a uniform spray distribution even at low pressure. These benefits make hollow cone nozzles commonly employed by users in the steel industry for spraying water mist during gas scrubbing processes. (More)
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- Principles, applications, pros, and cons of full cone spray nozzles
Principles
The solid cone nozzle is a spray device that undergoes internal structural modifications to achieve a curved shape. These nozzles feature a perforated or X-shaped center vane, known as a spoiler, to create a complete solid cone spray pattern. When liquid enters the nozzle through a conduit, it flows over the perforated or X-shaped center vane, generating two or more liquid streams that induce a swirling effect. As the liquid passes through the curved surface structure of the nozzle, it is ejected outward due to centrifugal force, resulting in a solid conical spray shape.
By adjusting the design of the central blade and the curved surface of the nozzle, the flow rate, spray angle, and distribution can be modified. The spoiler structure of the central blade separates the liquid, causing it to rotate inside the nozzle before spraying out at a specific angle. The liquid expelled by the solid cone nozzle rapidly forms a mist. Due to its structure and operating principle, the particle size of the sprayed droplets is typically larger than that of fan sprays. However, the solid cone nozzle provides uniform distribution over the entire sprayed area.
Pros
Solid cone nozzles are designed to generate highly concentrated fluid motion and can operate effectively at lower pressures. Moreover, they can be tailored to produce larger particle sizes, enabling the even distribution of liquids across surfaces.
Cons
- Due to limitations in liquid flow, they may not be capable of producing extremely fine particle size sprays.
- Solid cone nozzles are susceptible to clogging issues as a result of the inherent turbulence mechanism they employ.
Applications
In the semiconductor wet chemical cleaning process, achieving uniform treatment of each wafer with the chemical solution is essential, considering the wafer's size. Machine design must also consider the factor of spraying efficiency. Typically, a single nozzle is used to spray each wafer, utilizing a wafer-centric spraying design. Solid cone nozzles are commonly employed due to their high spraying efficiency and large coverage area. They generate larger droplets, ensuring even distribution of the liquid across the surface. With proper arrangement of spraying distance and angle, each wafer can be uniformly coated with the reacting liquid. While solid cone nozzles are susceptible to clogging, the semiconductor process environment demands high standards, and the presence of effective filtering equipment ensures that nozzle blockage is avoided. (More)
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- Principles, applications, pros, and cons of flood type spray nozzles
Principles
Flood type nozzles, also known as water curtain nozzles, low-pressure wide-angle fan nozzles, or wide-angle fan nozzles, operate by allowing liquid to enter the nozzle through pressure from a tube. The liquid then impacts the curved surface structure of the nozzle, guiding it to move in a direction that forms a certain angle with the flow of the liquid through the curved surface. This direction is where the liquid is sprayed out.
The defining characteristic of water curtain nozzles is that their structure must include a corner design. This design allows the liquid entering the nozzle and the direction of spray to form an angle. This angle is essential for guiding the flow of the liquid and utilizing the blocking effect caused by the flow and surface tension of the liquid. As a result, the liquid is sprayed in the intended direction, forming a continuous spray surface that sprays outward.
Pros
The spray design incorporates a reflective surface outside the nozzle hole, enhancing the passage capacity for foreign matter and effectively preventing clogging issues.
Cons
At operating pressures exceeding 4Kg/cm², there is a risk of liquid overflow without proper atomization.
Applications
Defoaming, also known as foam control, is a process used to address the issue of foam formation in tanks or pools on a large scale. In defoaming operations, the primary goal is to maximize the coverage area during spraying. Furthermore, foam can be effectively dispersed using low-pressure flushing. This eliminates the need for expensive high-pressure equipment and reduces energy consumption. Considering these factors, the optimal choice for defoaming application nozzles is the water curtain nozzle, which offers wide-angle fan-shaped spraying characteristics at low pressure. (More)
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- Principles, applications, pros, and cons of spiral nozzles
Principles
Once the liquid is pressurized and enters the nozzle through a tube, it encounters the helical structure inside. The helical structure guides the liquid outward and causes it to spray out at a specific angle through the helical surface. Due to the surface tension of the liquid, it follows the helical structure even after leaving the nozzle. As a result, the liquid continues to spray in the same direction, forming a spiral shape.
In general, the length of the nozzle's helical structure can vary, resulting in one, two, or three layers. Each layer corresponds to a different angle of spray. These angles typically range from 60 to 90 degrees for a narrow spray, 120 degrees for a wide-angle spray, and 170 degrees for an even wider spray.
Pros
- The unique structure and composition of spiral nozzles make them highly suitable for specific applications such as smoke control and air purification.
- The layered helical structure enables the spiral nozzle to spray at multiple angles, allowing for a larger coverage area. Unlike traditional nozzles that spray in a single plane, the spiral nozzle can spray in up to three layers simultaneously, expanding the spraying range from a surface to a three-dimensional space. This design is particularly effective for waste gas treatment as it increases the contact area between the liquid and the waste gas, enhancing efficiency and facilitating various chemical reactions.
- Spiral nozzles offer a significantly improved cleaning effect.
- They are less prone to clogging compared to other nozzle types.
Cons
- Spiral nozzles tend to be more expensive than other industrial nozzles due to their intricate structure and complex manufacturing process. Cheap imitation spiral nozzles are often produced using low-cost open mold injection techniques. These manufacturers lack an understanding of the layered design concept, resulting in uniform angles for each layer and difficulty achieving the desired spray effect characteristic of spiral nozzles.
- Proper functioning of spiral nozzles typically requires higher pressure, which may necessitate the use of a larger pump to generate sufficient pressure.
Applications
In semiconductor manufacturing facilities, waste gas treatment towers are commonly utilized to address the waste gas generated during the production process. The principle involves using sprays to combine water with harmful particles in the waste gas, forming wastewater that is easier to treat. The tower fillers are employed to extend the contact time between the gas and water, thereby increasing the surface area for gas-water interaction and enhancing the gas's solubility in water. Spiral nozzles, due to their simple flow path and resistance to clogging, are preferred over hollow conical nozzles for waste gas treatment. The spiral nozzle's three-layer spraying structure facilitates increased contact between the liquid and gas, resulting in improved waste gas treatment efficiency. Therefore, spiral nozzles are the optimal choice for waste gas treatment in towers. (More)
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- Principles, applications, pros, and cons of two-fluid spray nozzles
Principles
The fundamental principle of a two-fluid nozzle is to atomize the liquid by high-speed air, resulting in smaller liquid droplets and higher flow rates. This leads to improved cleaning efficiency as the smaller droplets have a larger contact surface area. When a liquid medication is sprayed using a two-fluid nozzle, the smaller droplet size allows for faster and more efficient reaction of the medication. In comparison, if other types of nozzles are used to spray the liquid medication onto the same surface, the larger droplet size may cause some of the medication to float on top of the previously sprayed liquid, preventing contact with the surface. As a result, some of the medication may not undergo the desired reaction. Therefore, using a two-fluid nozzle for chemical solution spraying may require only half or one-third of the amount of medication used with other types of nozzles to achieve the same effect.
Pros
- Capable of producing sprays with fine particle sizes, typically less than 50μm.
- The air pressure crushes the liquid, allowing for the use of high viscosity liquids.
Cons
- Involves a complex design.
- Requires high-pressure gas for operation.
- Prone to clogging issues.
- Requires high precision machining during manufacturing.
- Can be expensive.
- The small particle size of the sprayed liquid makes it susceptible to gasification, potentially filling the surrounding air with gasified liquid particles. In the case of corrosive liquids, complete isolation of the spraying area is necessary. Additionally, the gasification of the liquid results in higher liquid consumption.
Applications
In the PCB wet process, for etching blocks with line width and spacing less than 25um, a two-fluid nozzle is commonly employed. This nozzle crushes the liquid through high-speed air, enabling the liquid to penetrate the extremely narrow gaps. This process results in smaller liquid particle sizes and higher flow rates, ensuring smooth and even spraying of the liquid for a desired reaction. These unique characteristics make two-fluid nozzles a preferred choice in the PCB industry for specific process requirements.
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In conclusion, nozzles play a crucial role in various industrial and application fields. Single-fluid and dual-fluid nozzles offer different characteristics and can be chosen based on the desired spraying method. Different nozzle shapes, such as fan-shaped, hollow cone, and solid cone, have their own principles and applications. Water curtain nozzles create a cleansing and cooling effect through the creation of a water curtain. Spiral nozzles achieve continuous and uniform spraying through their unique spiral structure. Two-fluid nozzles produce smaller droplet sizes and higher flow velocities by utilizing high-speed air to break up the liquid. Each of these nozzle types has its advantages and applications, allowing for selection based on specific needs.
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參考資料
1. ⌃ Nozzle - Wikipedia
2. ⌃ Spray nozzle - Wikipedia
3. ⌃ Two Fluid Atomization Fundamentals (2017-07-23)
4. ⌃ Corrosionpedia Explains Spray Pattern (2019-2-15)
5. ⌃ Spray (liquid drop)_wikipedia (2017-11-30)
7. ⌃ Design and Optimization of Fan-Shaped Nozzle Structure Based on CFD (2020-10)
8. ⌃ Wikipedia-Fluid (2022-07)
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19. Coriolis Flowmeter Advantages and Limitations
20. Coriolis mass flow meter advantages and disadvantages