Safety and Efficiency with Electrostatic Guns
Electrostatic painting provides better transfer efficiency, lower disposal costs, increased productivity, and an environmentally friendly painting process, if executed in a safe and efficient way. With poor execution there is a possibility for safety hazards and reduced transfer efficiency.
Electrostatic painting is the process of putting an electrostatic charge in the paint itself. The goal of this process is to increase transfer efficiency by attracting the electron charged paint to the targeted object. However, because the paint on the part is charged with extra electrons it is important to make sure everything within the painting system is grounded to avoid shock, electrical hazards, and poor transfer efficiency.
“Grounding” ensures that the there is a direct electrical path from the part that needs to be sprayed to the true earth ground. A “true earth ground" is a measurement of one mega ohm or less. Place a megaohmmeter in the area needing to be tested to make sure you have a true earth ground.
Below are key areas that must be grounded in the electrostatic painting process:
When we talk about grounding from an operator’s standpoint, one of the contact points with the earth is the operator’s feet. If the operator is not properly grounded, the paint often times wraps back at the operator instead of being attracted to the target. Or in some cases, the paint will head to the floor. So, how do we avoid this?
We want to avoid all possible insulators:
- Do not wear insulated or rubber shoes. We recommend leather soles.
- Avoid the use of gloves. If a glove is worn make sure:
- The palm and the trigger finger are cut out to create direct skin contact with the glove.
- Or there is a conductive strip on the palm of the glove.
- Do not stand on paper unless it is conductive.
- Make sure the floor is clean and dry. Any paint overspray on the ground can act as an insulator.
The target is usually hung on hooks connected to a conveyor belt and then grounded through its connection to the wall.
The points to consider here are as follows:
- Where the hook connects to the target part.
- Where the hook connects to the conveyor.
- Commonly these areas will have paint overspray, causing an isolation of the target. When the target is isolated it results in a poor wrap. Keep hooks clean and grounded at all times.
The air hose is a special grounded air hose. Graco hoses have left handed threads to ensure the wrong air hose cannot be connected to the gun. The measurement from the hose to the grounded surface must again be no more than one mega ohm.
The paint supply could be any object in the paint booth that could accept an electric charge including the paint bucket, pump, and fluid hose.
There are two areas of focus in grounding the paint supply:
- Paint Bucket: Use a metal bucket directly in contact with the ground and connect a ground wire to a grounded location.
- Do NOT use a pail liner in your paint bucket.
- Pump: The pump is grounded by connecting the ground wire to a true earth ground.
- All other electrically conductive objects or devices in the spray area must be properly grounded.
It is important to test all of the discussed areas with a megaohmmeter before beginning to spray. If each one displays a mega ohm reading of one or less you are good to go. Remember, proper grounding ensures safety and good transfer efficiency throughout the painting process. So when it comes to electrostatic painting, stay grounded!
This information is intended to be a guide to the basics of grounding, for complete warnings and instructions refer to our electrostatic gun instruction manual 3A2494.