Comparing to those crucial electric components, tube is not a seriously concerned part for spray painting system configuration. However, a lot of people are still in puzzle when selecting, such as how to choose the type of tube between air and paint. Incorrect selection will bring direct problem of high efficient spraying and maintenance. Here we will take a comprehensive look at how to choose a tube and explain the difference between a paint and air tube.
In spray painting industry we mainly use the following 3 types tubes:
- PU air tube: made by high-resilience polyurethane material, it comes with excellent soft properties and usually used for air tube connection.
- PE tube: corrosion-resistance, the material is harder than PU.
- Double layer tube: the outer material is PU and inner Teflon, it combines the advantages of PU and PE that remains softness and corrosion-resistance.
Softness: PU tube > double layer tube > PE tube
Corrosion-resistance: double layer tube >PE tube > PU tube
So how to actually use for a spray gun connection?
- The spray gun air intake uses PU tube(the same standard for both manual guns and automatic guns).
- The paint intake tube uses PE pipe and double-layer oil pipe (manual and automatic spray gun)
The main reason is most paints come with corrosive property, so corrosion-resistance tubes is recommended(PE tube and double-layer tube). If we use PU tube for paint connection, it will be broken after some periods operation. At the same time, due to increased pipe diameter by corrosion, the corroded pipe will not be smooth, resulting in a large amount of paint remaining, those small solidified particles will flow to the spray gun nozzle during use, thereby blocking the spray gun.
In addition, there are cost considerations when choosing PE and double-layer tubes. The price of PE tube is lower, but the tube cannot be folded, so it’s generally used on fixed automatic spray guns. The price of the double-layer tube is relatively high, but it has foldable characteristics, it is often used on manual spray gun or robotic arm or when the paint is relatively high corrossive.
Therefore, we will not use PU air tube for both air and paint(very common issue). Although it is convenient, there will be a series of problems in spraying work.
How to connect spray gun?
Spray gun is normally central control with a control panel. The connection between the spray gun and the automatic spraying control cabinet is actually very simple. We mainly need to understand the following two points to quickly install and connect the spray gun.
1- Understand how many air inlets are required for an automatic spray gun, and which ones need to be connected to the pressure regulator and solenoid valve.
For example the WRA spray gun，there are CYL (gun needle control), CAP (atomization control), FAN (fan size control). In this way, we need three air intakes, just need to find the corresponding group of air outlets in the control box. Of course, each control cabinet is not only for a single spray gun control, so we need to arrange each air tube properly when connecting.
Also remember which controls the gun to open, atomize, and fan size. Then connect in the same order as the previous ones.
2- Paint tube system
In fact, most of the paint circuits are directly connection from the pneumatic diaphragm pump, the general spray control cabinet does not control paint supply system (unless there are special requirements). Then the second note is need to know if the gun needs to be connected to flow back to paint drum. If the paint is required to return, spray gun needs to be connected with return tube.
