author
Bobby Brown
Post 2023-10-06
Quick Guide to Nozzle Spray Principles and the Pros and Cons

Contents


What Are Nozzles?

Live-action of nozzle spraying

Nozzles are widely used across industries and applications to break fluids into spray patterns, categorized into single-fluid and two-fluid types. Single-fluid nozzles consist of a nozzle hole and a fluid inlet, producing various spray patterns. Two-fluid nozzles use two different fluids mixed together to achieve a more diverse spray effect. Common spray patterns include fan, hollow cone, solid cone, spiral, and cylindrical, each with specific applications and advantages, such as high-pressure washing in the car wash industry and low-pressure, uniform spraying in electroplating equipment washing processes.

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Single-fluid vs Two-fluid Nozzles

Single-fluid and Two-fluid nozzles
  • Single-fluid (or single-phase) and two-fluid (or dual-phase) nozzles are common types. Single-fluid nozzles use one channel for the liquid to create a single jet, ideal for misting, coating, and cleaning applications. They operate under liquid pressure only, without the need for compressed air, producing a coarser average spray droplet size. 
  • Two-fluid nozzles have both a gas and a liquid channel, mixing inside the nozzle to create a fine, uniform jet, used for spraying medicines, paints, and fuels. However, two-fluid spraying with chemicals may accelerate the degradation due to oxidation with air, requiring careful dosage management.
[2][3]

Common Nozzle Spray Patterns

Spray Patterns ( Shape: fan, full-cone, hollow

Spray patterns are shapes of liquid released from pressurized sources, crucial for achieving uniform liquid coatings. Different nozzles produce various shapes like cone, fan, circle, and line, each suited for specific scenarios. Understanding and selecting the appropriate spray pattern is vital for optimal application results.

For more detail about spray patterns, please check ''Nozzle Spray Patterns: The Key to Cost-Saving and Efficiency in Industry''

Spray patterns are shapes of liquid released from pressurized sources, crucial for achieving uniform liquid coatings. Different nozzles produce various shapes like cone, fan, circle, and line, each suited for specific scenarios. Understanding and selecting the appropriate spray pattern is vital for optimal application results.

[4]

The Principles of Nozzle Spray and the Pros and Cons

Fan Nozzle

Principle

Fan Nozzle
Fan nozzles, a common nozzle type, work by pressurizing liquid through an elliptical outlet, creating a fan-shaped spray due to pressure not being released evenly, hence the name. Advantages
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Advantages:

  • Widely used and beginner-friendly
  • Simple structure for basic nozzle control
  • Less prone to clogging
  • Provides the best impact among nozzle types

Disadvantages:

  • Compared to solid cone nozzles, fan nozzles in a stationary position require more units for equal area coverage, making them less efficient

Applications

Car Washes:
Fan nozzles are often used for washing, especially in car washes. Despite their lower efficiency compared to solid cone nozzles, their lower cost and maintenance, coupled with the movement of car wash machines, compensate for these disadvantages, making them a practical choice for thorough cleaning tasks.

Hollow Cone Nozzle

Principle

Hollow Cone Nozzle
Known as vortex-type spray nozzles, hollow cone nozzles create tornado-like vortex flows inside through a cavity structure. The liquid is directed outward through the nozzle's curved opening, forming a hollow cone spray shape. This nozzle is excellent for applications requiring fine misting without the need for compressors, offering easy installation and cost savings.

Advantages:

  • Produces fine spray droplets, usable at low pressure
  • Ensures uniform spray distribution
  • Simple channel design minimizes blockage by foreign objects

Disadvantages:

  • May result in uneven spraying at high pressures
  • Does not cover the center as efficiently as the outer area

Application

Steel Industry
Used in scrubbing towers to mix water mist with dusty gases, facilitating the capture of dust through inertial collision and diffusion adhesion on the water film formed on the packing material's surface. Its simplicity and large passageway make it ideal for the steel industry, where fluids often contain impurities.

Solid Cone Nozzle

Principle

Solid Cone Nozzle
Solid cone nozzles, with their internally processed curved shapes and multiple or X-shaped central vanes, generate a complete solid cone spray. The liquid, divided by these vanes, spins and ejects in a solid cone shape, distributing uniformly over a wide area despite producing larger droplet sizes than fan sprays.

Advantages:

  • Generates highly concentrated fluid motion, working well under lower pressures, and distributes liquid evenly with larger droplet sizes.

Disadvantages:

  • May not produce very fine droplets due to flow limitation and can get blocked due to the internal turbulence mechanism.

Application

Semiconductor Wet Chemical Cleaning
In semiconductor processes, where uniform treatment of each wafer is crucial, the design of machinery often relies on the efficiency of a single nozzle spraying a wafer. Solid cone nozzles, with their large coverage and droplet size, ensure even application of chemicals, although they may get blocked, a risk mitigated by high-quality filtration systems.

Water Curtain Nozzle

Principle

Water Curtain Nozzle
Water curtain nozzles, also known as flood, water screen, low-pressure wide-angle fan, or wide-angle fan nozzles, direct liquid through a curved structure to create a continuous flow in a specific direction, thanks to surface tension. These nozzles feature a unique design that guides liquid flow at an angle, producing a spraying face that extends outward.

Advantages:

Achieves spray design using reflective surfaces outside the nozzle orifice, enhancing passage capacity for foreign objects and reducing blockage risk.

Disadvantages:

High operating pressures over 4Kg/cm² might result in unatomized liquid overflow.

Application

Foam Control
Ideal for defoaming applications where large area coverage is essential, and the low-pressure wash can dissipate foam. Their design offers a cost-effective, energy-saving solution without the need for high-pressure equipment.

Spiral Nozzle

Principle

Spiral Nozzle
The spiral nozzle uses pressure to guide the liquid through a spiral structure, resulting in a continuous spiral spray. It's differentiated by one, two, or three layers, with spray angles of 60-90 degrees, 120 degrees, and up to 170 degrees, respectively.

Advantages:

  • Unique structure suited for smoke control and air purification
  • Multilayer spraying increases the coverage area significantly
  • Highly effective for cleaning and not prone to clogging

Disadvantages:

  • Complexity and high manufacturing costs compared to other nozzles.
  • Requires more pressure to operate, potentially needing larger pumps.

Application

Waste Treatment Towers
In semiconductor plants, waste treatment towers utilize spray nozzles to combine water with harmful particles from waste gas, creating easily treatable wastewater. The spiral nozzle's straightforward design prevents clogging and enhances gas-to-liquid contact area compared to hollow cone nozzles. Its triple-layer spraying structure maximizes the interface between the liquid and gas, thereby improving the efficiency of waste gas treatment. This makes spiral nozzles a prime choice for use within waste gas treatment towers.

Two-fluid Nozzle

Principle

Two-fluid Nozzle
The two-fluid nozzle operates on the principle of using high-speed air to atomize liquid into finer droplets, resulting in a spray with smaller droplet sizes and higher velocities for improved cleaning effects. This nozzle type is especially beneficial for processes requiring precise and efficient spraying, such as in the PCB wet process, where its ability to produce fine droplets enhances reaction efficiency and coverage even in narrow spaces.

Advantages:

  • Produces fine droplets (smaller than 50μm).
  • Capable of handling high-viscosity liquids.

Disadvantages:

  • Complex design.
  • Requires high-pressure gas.
  • Prone to clogging.
  • Demands high-precision manufacturing.
  • Expensive.
  • Small droplets may lead to vaporization, increasing consumption and requiring isolation for corrosive liquids.

Application

PCB Process
Ideal for etching processes on PCBs with line widths and spacings under 25um, the two-fluid nozzle's fine spray ensures even chemical distribution and reaction, making it a preferred choice for specialized PCB manufacturing processes.

In summary, nozzles play a crucial role in modern industry and application fields. Single-fluid and two-fluid nozzles each have unique characteristics, allowing for the selection of an appropriate spraying method based on needs. Different nozzle shapes, such as fan, hollow cone, and solid cone, have their own principles and applications. Water curtain nozzles create a cleaning and cooling effect, spiral nozzles achieve continuous and uniform spraying through their unique structure, and two-fluid nozzles produce finer droplets and higher velocities. These varying types offer distinct advantages and applications, enabling tailored solutions for specific requirements.

References

  1. ^ Nozzle - Wikipedia
  2. ^ Spray nozzle - Wikipedia
  3. ^ Two Fluid Atomization Fundamentals
  4. ^ Corrosionpedia Explains Spray Pattern
  5. ^ Spray (liquid drop)_wikipedia
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