WHAT TO CONSIDER WHEN CHOOSING AN AIRLESS COATINGS SPRAYER
Equipment selection is crucial to the achievement of airless spraying of industrial coatings. No matter whichever market you serve, the machine must dependably deliver a select coating type at the right application rate under different operating conditions. If the equipment is not correctly suited for the job, quality concerns, and equipment failures often lead to budget overruns, schedule delays, and unhappy customers.
The key to airless spraying is producing enough fluid pressure at the gun to atomize the substance into a pattern that provides consistent coverage. Many factors need to be considered when selecting airless spraying machines, including an available power supply, coating type, application demand, the distance between the pump and spray gun, operating environment, portability, and maintenance specifications.
Airless pumps can be powered by air, electric, or gas power sources. The selection of power is often determined by the operating conditions and availability of power sources. The key factors of each source are shown below.
Power Source Pros Cons
- Convenient for builders using air-compressor-driven blasting equipment
- Safer in explosive environments
- Capable of handling large tip sizes
- Capable of operating multiple spray guns
- Easily handles long spray hoses
- Noisier than other kinds
- Can be inclined to icing in cold environments
- Requires a large-sized compressor
- Quieter than other sources
- Reduces energy costs
- Less prone to icing
- Does not demand a large compressor
- Handles long spray hoses
- Need 240V on-site as well as an electrician
- Only works with smaller tip-sizes
- Greater portability
- Capable of high production rates
- Helpful in handling heavier, thicker coatings
- All-in-one power source (does not require electricity or compressor)
- Not allowed in hazardous environments
- May need permits for fuel on Jobsite.
MATERIAL & APPLICATION
MATERIAL BEING SPRAYED
The coating model also plays a key role in spray equipment. Industrial coatings are typically epoxy, polyurea, or polyurethane-based, highly viscous materials. Higher pressure pumps allow pumping more viscous materials and optimizing pressures for less dense substances.
If solvents are used to lower viscosity, one key factor to consider is the length of time the material needs to be sprayable after being hand-mixed (hot potted). The proportion of solids in the coating is another key factor. As the solids percentage increases, the number of the solvent decreases, and pot life decreases.
The rate at which coating is to be sprayed, or application demand, is also a key factor in selecting spraying equipment. The pressure required to atomize the material often determines the appropriate pump. Tip size required for proper coverage, the number of guns, duty cycle, and pump flow rate also need to be analyzed.
A combination of both pressure and flow of the pump determines the application rate. Many pumps have enough pressure to spray a coating, but they’re offered in different sizes (or flow rates).
The flow rate that the pump is capable of achieving also needs to be considered. For example, a sprayer with a larger pump fluid section can handle more demanding applications because it cycles slower.
DISTANCE & ENVIRONMENT
DISTANCE FROM PUMP TO GUN
To properly atomize and apply coating material, the pump must overcome the pressure drop in the hose. As hose lengths increase, pressure drops increase, and additional pumping pressure is needed.
The diameter of the spray hose also affects the pressure drop. By increasing the hose diameter, pressure drop can be reduced. Elevation of the application area can also affect the pressure drop. If the application area is higher than the sprayer, a larger pressure drop will occur through the hose. Coating suppliers and product data sheets can provide additional information on the pressure required.
Various operating environments demand different spraying equipment. Temperature and humidity are often key factors to consider. Air motors can experience icing issues, as ambient air is compressed and exhausted out of the pump at a colder temperature. A good motor design will mitigate icing and possible pressure loss. Some advanced sprayers feature thermally isolated poppets on the motors insulated from motor castings to virtually eliminate pilot valve freezing.
If sprayers are used in hazardous locations, pump type must be considered. Gas pumps are generally not allowed in these areas. If an electric pump is being used, agency approval is needed for operation in a hazardous location.
Portability is a different factor to consider. Most sprayers are typically available on carts and may be moved around a job site. Pump size can also affect portability. While larger pumps often help achieve higher application rates, the pump size should also be optimized to maximize portability. In industrial environments and smaller projects, if one person can maneuver a sprayer, a smaller unit at a lower cost may make sense.
A sprayer that’s easy to troubleshoot and maintain will make life easier – and jobs more profitable. The equipment dealer can advise on ease of maintenance, regular maintenance tasks, and anticipated lifespan of wear items for various sprayers. Some key maintenance questions to ask:
- Are common items easily accessible, or is disassembly required?
- Are any special tools required, or can common tools handle most maintenance tasks?
- How easy is it to remove the cover?
- Is there a convenient place on the sprayer to store essential tools and parts?
- Are replacement parts reasonably priced and readily available?
Each of the factors discussed in this article (power source, coating type, application demand, the distance between the pump and spray gun, operating environment, portability, and maintenance requirements) plays a key role in selecting an airless sprayer.) Also, here are some general items to consider when selecting equipment:
- Make sure you have sufficient fluid pressure at the gun to provide consistent coverage.
- A dependable, high-quality sprayer may have a higher initial cost, but the successful completion of more jobs on time is possible if you consider all the right factors.
- Rugged sprayers can perform various environmental conditions and make the difference between a good day’s work and a day of frustrating delays.
- Work with a qualified technical representative to make the right decision