Science of Static Control
Electricity plays a key role in our lives. Can you imagine getting to work this morning without it? That would mean no lights, no alarm clock, no heat and a cold shower. Doesn’t sound like much fun does it? An example of static electricity is lightning. When it lights up the sky and crackles with millions of volts of energy, we stand in awe at the power of Mother Nature. These are common examples of electricity that we all recognize and respect. However, very few cleaners see much connection between static electricity and our daily tasks like dusting, sweeping and vacuuming.
It is important to realize that minute electrical charges play a key role in cleaning and soil attraction. All non-conductive particles and surfaces have an electrical charge, either negative or positive. You probably remember playing with a magnet and iron filings in science class when you were in grade school. Those same principles apply to soil and surfaces today. Like charges repel, unlike charges attract. If the surface has a positive charge and the soil has a negative charge, an electrostatic attraction is created. The soil is actually drawn or attracted to the surface and holds tight to it. A good example of this is a positively charged video screen on a computer that accumulates a thick layer of negatively charged dust from the air. This minute electrical charge speeds up the soiling process and makes cleaning more difficult and this applies to most of the surfaces that we clean each day.
Static electricity also creates problems when it comes to delicate electrical components found in computers and other devices. A small charge, one you can’t even feel or see, can confuse or destroy a chip or circuit on contact. This little spark can result in down time, lost data and thousands of dollars in damage. If you have ever spent hours entering data only to have it evaporate into thin air, you know how frustrating and costly that can be.
The generation of static electricity cannot be completely prevented. It’s a natural phenomenon. However, it can be managed and controlled with a comprehensive Electrostatic Discharge Program (ESD). For a program to be effective it must be tailored to the specific needs of each area of a facility be it electronic, medical, military, biological, manufacturing or chemical in nature.
Every ESD program should cover the following points:
- Prevention: To minimize static accumulation on materials of construction and clothing.
- Elimination: To provide a conductive path or ground for charge dissipation.
- Training of all workers involved in the process.
- Monitoring on a regular basis with well-maintained test equipment.
Preventing Static Build Up
There are a number of steps you can take to reduce soiling and problems related to static charges. The first place to start is to be aware of and control the temperature and humidity in the work place. The higher the temperature and the lower the humidity the more static electricity you will have. If you lower the temperature and raise the humidity in the air you will have less problems with static electricity. If the humidity in the building or work area is below 50% you can expect to have more of a static problem. This can be controlled by adjustments to some HVAC systems or by adding portable humidifiers in problem areas. Your engineering department should be able to guide you in this area.
The second place to attack the problem is by using proper cleaning techniques. It is important to use processes and equipment that capture and remove soil instead of spreading it around. Some examples include walk off mats at all entrances and the elimination of certain dry cleaning processes such as feather dusting, dust mopping and sweeping. These should be replaced by systems and procedures that capture and hold soil. A good example of this would be to use a back pack type vacuum with a HEPA filter that captures the very small micron sized particles of dust and soil that are most affected by static charges. Dry dusting should be replaced by wet wiping. It is important to stress the need for regular daily vacuuming of all mats and floor surfaces. Regular deep cleaning of entrance mats and carpets will remove soil and prevent these surfaces from becoming a contamination source instead of a way to remove and capture soil from shoes and wheels.
The third element is to use special conductive surfaces such as mats, flooring, carpet and counters. In highly sensitive environments, employees will attach a grounding strap to their wrist and to the item they are working on to further reduce the possibility of any static discharge that may cause damage to the component they come in contact with.
And lastly, but also very important, is to use chemical products and treatments that are made specifically to prevent the build up of or to dissipate a static charge. Examples of these include anti-static treatments for carpet, floor finish, specialty cleaners, and coatings for other surfaces. Anti-static sprays provide a surface coating or protective film that neutralizes static charges on such surfaces as carts, chairs, fabrics, plastics, carpet, conveyor belts, walls, vents and other items that workers or components may come in contact with during manufacture or transport.
The basic concept here is to maintain a direct conductive path to ground neutral. This includes such things as keeping all ground strapping equipment in good working order and maintaining all contact and walking surfaces in a clean and effective static dissipating state.
One of the most important areas to maintain is the floor, since it is the largest and most widely used and easily soiled surface. Floor finish can be used as a secondary protective coating over other surfaces. It is important to use a high quality, environmentally safe floor finish that is durable, buff-able, nonflammable, biodegradable, scuff, scrub and slip resistant and easily maintains its resistance rating.
To maintain the integrity of the conductivity it is important that all products used on such surfaces are from the same manufacturer or approved for use by the manufacturer of the floor covering material and the finish.
Normal detergents and alkaline cleaners should not be used, as they tend to leach out or leave a residue on the surface that will impede the ability of the finish’s conductive properties.
Areas where static control is of concern present special challenges for the cleaning staff. These challenges need not be prohibitively expensive or insurmountable if everyone involved understands what needs to be done and what specific procedures are followed on a regular basis.
Quality products, adequate frequencies and ongoing employee training are key elements that must not be overlooked when setting up or troubleshooting an existing cleaning program for ESD areas.