Agricultural, industrial, and manufacturing processes rely on spray nozzles for cleaning, applying liquids in applications, and for cooling methods. Certain applications require a specific droplet size as well as coverage, such as cleaning out storage containers to remove grime from the corners and stripping heat from air streams for pollution control. The sprayer pressure directly impacts droplets sizes and spray angles, which could cause issues such as drift or over-saturation.
How Sprayer Pressure Affects Droplet Size
We define pressure as pounds per square inch (psi), which is the amount of force that a pound of liquid has to one square inch of area. It is then further categorized as low pressure, normal pressure, and high pressure. Low pressure is typically 15 psi or lower, while high pressure can range from 40psi and higher. The application itself will dictate the type of pressure needed from the sprayer.
When it comes to droplet sizes, lower pressure produces medium to large droplets. Higher pressure creates small and fine droplets. This factor is due to how the flow rate exits the orifice of the nozzle in the desired spray pattern.
Relationship Between Pressure and Droplet Size
When sprayer pressure is low, the droplets become larger since not as much liquid is traveling quickly through the nozzle. You obtain coarser droplets with less of a defined or uniform droplet size. There is less liquid spraying over the specific area in a narrower pattern, whether you are using flat fan, hollow cone, or full cone spray nozzles.
On the other hand, higher pressure causes more water to travel through the nozzle in liters per minute. Droplet sizes become smaller when leaving the orifice due to the force of water entering the air. These fine droplets are more numerous as they have a more uniform size.
Importance of Droplet Size in Different Applications
Applications require different droplet sizes based on functionality, available flow rates, and nozzle sizes. By adjusting the sprayer pressure and other aspects, you can get the desired droplets to accomplish the task at hand.
Agriculture (Pesticide Application)
For pesticide applications in the agriculture industry, the flow rate can vary depending on the type of pesticide used for the application. You may require a fine mist to apply pesticide directly onto plants to coarser droplets applied to the soil and roots. Pesticide products will list instructions on the manufacturing label regarding the amount of saturation per acre based on gallons of water that will be applied.
Industrial Processes
Industrial processes rely on spray nozzles for cooling applications, cleaning, and applying liquids to products or machinery. In some cases, fine mist droplets are preferred for dust mitigation as well as pollution control. The different droplet sizes are important to industrial processes as the liquid needs to fully interact with the application. Care must also be taken to prevent liquid oversaturation that could damage products or equipment.
Precision Applications in Manufacturing
Cleaning and lubrication are two common applications for precision manufacturing. Spray nozzles may apply lubricants to conveyor bolts, moving parts, and even molds to ensure parts can be removed smoothly without damage. Products that undergo grinding, drilling, or welding may also require cleaning prior to machining or afterward during finishing processes.
The Influence of Sprayer Pressure on Coverage Quality
The sprayer pressure can impact the flow rate, which in turn changes the coverage pattern of the liquid. If the flow rate is high, the liquid moves faster. Depending on the height of the sprayer, a high pressure increases the spray angle, which could cause the liquid to go beyond the parameters of the application area. A lower pressure can ensure that the spray reaches all areas by reducing the spray angle.
Higher vs Lower Pressure: How It Changes Spray Patterns
Even when using the same style of nozzle, the spray pressure will influence the spray pattern. Low sprayer pressure will create a narrow spray pattern. A wider pattern will emerge for higher flow rates. Wider patterns will use up more liquid, which could lead to unnecessary liquid waste.
Ensuing Even Coverage for Optimal Results
Having a greater understanding about flow rates and droplet sizes will allow you to match the right spray nozzle size to the application. You want a nozzle that can work with the flow rates that are present in your operations. It should provide you with the droplet sizes to provide full functionality while reducing waste and keeping your operational costs within budget.
Avoiding Issues Like Drift and Over-Saturation
Spray drift occurs when the liquid droplets move from their intended area. This problem may be caused by environmental factors such as wind movement. It can also be caused by poor calibration of the sprayer equipment. Over-saturation can occur where there are too many water droplets that soak into the application, which can cause damage or delays.
To avoid drift and over-saturation, you should lower the liquid pressure and increase the nozzle size for coarser droplets. It will give you larger droplets that won't be subject to drifting while using less fluid to avoid over-saturation. You can also adjust the height of the nozzle in relation to the application.
Choosing the Right Pressure Settings for Specific Applications
Your application will dictate the type of pressure that is required, whether you are looking for coarser droplets for cleaning or fine droplets for humidification. Understanding the flow rates for your systems can allow you to select the right sprayer, nozzle size, and spray pattern.
Matching Pressure to Desired Droplet Size
Keep in mind that the size of the droplet will increase based on the flow rate. At the same token, the size of the droplet decreases when you lower the pressure. Understanding the needs of the application, studying industrial standards for spray nozzles for the specific application, and performing droplet tests will allow you to adjust the pressure to obtain the desired droplet size.
Adjusting Pressure for Application Conditions
Temperature, wind, and even the surface type can impact the types of droplets required for the application. If dealing with elevated temperatures, you'll need to select a droplet size that will not quickly evaporate before reaching the surface. If you are dealing with surfaces that absorb too much water, you want a smaller droplet size to avoid over-saturation.
Lechler's Expertise in Precision Spray Nozzles and Pressure Control
Lechler's custom and turnkey spray technologies provide customers with versatile nozzles that can handle low and high pressures to provide the optimal droplet sizes and even droplet distribution. Your application obtains the desired coverage required while helping to conserve water resources. Let our pressure nozzles maximize sprayer efficiency. Contact us today.
