Static Electricity and How It Can Be Prevented in Your GEMCO Mixer
STATIC CHARGE DISSAPATION
Static dissipation in GEMCO blenders ensures safe and efficient mixing
The friction of two materials rubbing against each other causes the “triboelectric” phenomenon known as static charge. In equipment, static buildup often is seen in blenders, mills and screeners. A blending system may generate significant amounts of static electricity. If the static electricity does not have a grounded path to follow it can lead to an ESD (Electro Static Discharge). An uncontrolled ESD occurrence can, in turn, cause short circuiting of electronic components, induce a fire or cause difficulties in powder discharge or flow during processing.
Static charges cause:
- Unsafe working conditions
- Segregation at discharge
- Slow or inefficient mixing
- Excessive powder residue left on blender walls.
Environmental variables such as relative humidity influence the level of electrostatic charges.
When humidity is low, higher static charges will typically be generated. For this reason, static becomes more noticeable in the winter months, in dry climates, and if air-conditioning is used.
One method to decrease the presence of static electricity is to increase relative humidity. By increasing the humidity to 60% in the area surrounding the static build-up you will reduce the opportunity for uncontrolled ESD. Surface moisture on materials will act as a conductor. This ‘solution’ of relative humidity is however extremely uncomfortable, can cause equipment problems and introduce biological contaminants into your equipment.
As an effective alternative, a custom static control brush or bar can be simply engineered to control or eliminate an ESD. Static control contactors allow blenders to mix more efficiently and stop powders from “rat holing” or layering the vessel walls caused by charged particles “sticking” to one another and the blender walls. Of course, a properly placed static control contactor will also help to prevent electronic component damage caused by ESD.
Proper placement of the static control contact bar or brush
Static control brushes work by induction, much like a lightning rod. Physical contact between the static eliminator brush and the target material is not necessary. Putting static control brushes in very close proximity with the material being moved will provide a path to ground thereby neutralizing a static charge. Your static control brush should be positioned inside the equipment at a point after the static charge has been created. Proper positioning provides the ESD static dissipation capability prior to any static-induced problem within the machine. GEMCO has tested both brushes and bars to determine proper placement with the conducting materials used in its design. To work effectively, your static control brush must be grounded.