The Differences between Gravity, Suction, and Pressure fed spray guns (Includes Video)
In finishing you can feed material into a spray gun via gravity, suction, or pressure. Each method of material delivery has various benefits and drawbacks, in this post we will cover those benefits and drawbacks first in a condensed summary and second in a greater in depth review. For an idea of whether you would want to use a Conventional, HVLP, or LVMP Spray Gun you can check out this article.
Short List of Benefits and Drawbacks plus common uses of Gravity, Suction, and Pressure Fed Spray Guns
Pressure Fed Spray Gun Benefits and Drawbacks
- Best control of painting due to being able to control fluid and air pressure separately (if you purchase a dual regulated pressure tank)
- Able to spray any coating no matter how viscous due to being able to increase the pressure of the fluid being fed to the spray gun
- Better suited for high volume coating use as it will hold anywhere from 2 – 50 gallons depending on the pressure tank’s size
- Able to leave the system with coating in it as long as the coating doesn’t have a limited pot life
- Will require a separate pressure tank which can lead to a total cost for a pressure fed spray gun of around $950 vs anywhere from $150 – $450 for a gravity or suction fed spray gun
- Clean up is a bit longer of a process when compared to gravity or suction fed spray gun
- Extra hose can create a little more bulk leading to the pressure tank system being a bit less comfortable to work with
- Applying coatings like latex paints, stains, sealers, top coats, long life epoxies, zincs, and lacquers to wood or steel. Most commonly used with higher volume or heavier bodied coating application needs.
Gravity Fed Spray Guns Benefits and Drawbacks
- Portable – only need the air supply hose, their is not a second line for fluid pressure
- More affordable than a pressure tank and pressure fed spray gun
- Easier clean up than a pressure pot
- Can provide smaller volume of paint at a time than a pressure fed spray gun
- Material has to be able to flow via gravity well to be able to be sprayed well with a gravity fed spray gun. This means it will not work well with heavy bodied coatings.
- Can be difficult to paint with gun upside down unless you buy add on system like a Dekups system.
- Small wood projects that will not use a lot of material
- Automotive car repair
- Touch up on larger jobs
- Color matching for a production layout
Suction Fed Spray Gun
- Atomization will occur naturally as air required to feed material to the spray gun will automatically create the atomization you need
- Portable similar to a gravity fed spray gun
- Able to spray upside down in weird positions without a problem
- Limited control over atomization air supplied to the gun
- Difficult to use with heavy bodied materials
- Wood finishing is a frequent use for suction fed spray guns due to the natural tendency of a suction fed spray gun to create proper atomization because of the guns air requirements to feed material to the gun
- Touch up work in metal finishing projects
Benefits and Drawbacks of Pressure, Gravity, and Suction Fed Spray Guns – The Long Version
The best way to think of the methods of delivery is to break down what matters most to you as a user. For example, if control of material and atomization air is your primary control, pressure fed spray guns are going to provide the best control. More specifically pressure fed spray guns that utilize a pressure tank with dual regulators. A dual regulated pressure tank gives you precise control over pressure of fluid both to the material and to the air that breaks the material up (the atomization air). An additional benefit of pressure guns is that they can spray thicker materials where gravity and suction spray guns may not effectively move material through the gun due to the material being to thick. You can also leave material in the pressure pot as long as the coating doesn’t have a pot life. The downside of pressure guns is they can be more expensive because you typically have to have both a spray gun and a pressure tank rather than a gravity or suction spray gun that do not have a pressure tank as a seperate expense. For a quality ASME Pressure Tank with dual regulation, hoses, and a high quality HVLP Spray Gun you will typically spend about $930.00. Comparatively a high quality gravity or suction fed spray gun will anywhere between $150 – $400.