Recirculating Paint Line Problems and Solutions
Recirculating paint lines can often times be a bit more involved than your everyday spray gun and pressure pot outfit. Knowing how to properly fix problems in a recirculating paint line can help you ensure that your production is not interrupted and you can continue to move product. The following tips will give you a great way to determine what is wrong with your recirculating paint line.
Problem Area 1 – Fluid Delivery
In an automated paint line the first area that can potentially be problematic is the spray equipment that is delivering material to your system. Depending on your recirculating line you may have a diaphragm pump or airless piston pump are common fluid delivery methods. If you’re having problems with spray guns that do not have a constant flow of material during spray the fluid delivery would be the first place to look. Things to check include whether or not the airless sprayer pump will provide a sufficient volume of coating based on your airless tips. To know the volume of material your tip requires you can use this reference chart. You will want to consider an airless pump that will provide anywhere from 25 – 40% more fluid than your tips may need, this will allow the pump to not be overworked as the tips wear. You also want to verify that the pump is moving smoothly in both the up and down stroke, if it is not it may need new packings or balls and seats. In addition to the pump you will also want to check all fluid filters in your line if there are any. You want to ensure the fluid filters are cleaned. If you have fluid filters that routinely plug you will want to consider changing mesh sizes to a smaller number mesh. However, if your spray gun tips routinely plug you will want to consider using a larger mesh number as this will prevent material from plugging in your fluid tip.
With a diaphragm pump you will want to consider if the pump is moving evenly in both directions. If not there may be damage to the internal gaskets within the pump or the ball valves. This can cause the spray pattern to change continuously effecting the spray pattern. You will also want to ensure your diaphragm pump is oversized similarly to an airless pump with an extra 25-40% more fluid than your air spray gun tip will need. You can get an idea of fluid tip and coating volume use here. If your pump is routinely wearing out you may need a bigger diaphragm pump or different internal material.
Problem Area 2 – The Fluid Lines
If you determine your pump is appropriate for your spray guns you then want to ensure you fluid lines are not blocked. If you have a blocked off fluid line you will find material delivery will be insufficient. To help reduce the chance of this happening again you can be diligent about solvent flushing your recirculation system routinely. You can also consider a solvent saver flush unit that can help better clean your paint lines as issues arise.
Problem Area 3 – Spray Guns
If your spray guns drip or have spray patterns that differ and the other components to your system seem ok you should then check your spray guns. A good overview of spray gun problems and there solutions is here. For recirculating paint lines the guns are usually air triggered so you can also see if the spray gun is not triggering the air actuated trigger may need repaired.
Problem Area 4 – Regulators
If all other components to your recirculating paint system seem ok you should check your regulators. If you notice that there doesn’t seem to be any pressure in your line and the airless or diaphragm pump is working correctly you can check your back pressure regulator. The back pressure regulator keeps pressure in the fluid line and if it is worn out or no longer effective there will not be sufficient pressure in the line and you could see that the pattern is not consistent or there is no fluid delivery at all after the gun is triggered.
Problem Area 5 – Controls
Depending on the type of recirculating paint line you have you may have a PLC controlled aspect to the line. You will want to verify that the PLC is triggering and that the air actuator that actually triggers individual spray guns is being triggered. You can usually manually trigger the air actuator to ensure they are working and if it is you may have an issue with a PLC. This is a very simplistic overview of the controls in a recirculating paint line and you often times need a specialist for your specific line to provide guidance on repair.
If you have questions or need assistance with any of the equipment concepts we mentioned please let us know.