3 Maintenance of Static Control Systems 8200 Mats Technical Brief - July, 1983 The basic purpose of conductive work surfaces is to provide a surface that is free of static charge and also is capable of removing the static charge from conductive items placed on it. The total resistance to ground determines the level of charge and rate at which it will be drained. A resistance to ground of 1000 megohms or less is required on an 8200 mat to drain a charge to a level of 100 volts or less in one second from a person or tote box charged to 5KV (ref.1, 2). Resistance Measurement: Measuring the resistance of the mat requires a high voltage megohmmeter. The megohmmeter must have a test voltage of 50-100 volts and a meter range of 0-1000 megohms. The ground lead of the megohmmeter is attached to the ground points of the mat. The other lead of megohmmeter is attached to an electrode that is described in both ASTM F 150 and NFPA 56A paragraph 4-6.2.7(b). The resistance to ground should be greater than 106 ohms and less than 109 ohms. if the resistance is less than 106 ohms, an alternate path to ground has been established which bypasses the one megohm resistor in the ground cord. If the resistance is greater than 109 ohms, the ground connection has been interrupted. Cleaning: Mats should be periodically cleaned with a detergent and water solution. To reduce the possibility of leaving a residue, detergents (rather than soaps) should be used. Powdered detergents such as Tide(R), Ajax(R), etc. should be added to water at a 1-2% concentration, liquid detergents such as Wisk(R), All(R), etc. at a 2-3% concentration, and general purpose cleaners such as 409(R), Mr. Clean(R), etc. can be used full strength. Normally, only a cloth that is thoroughly wetted with the detergent solution is needed to wipe off the mat; however, hardened stains may require brushing with a semirigid bristled brush. The wiping or brushing action should be in a circular motion to ensure removal of the particles from the surface depressions. Extremely soiled mats may require several repeated cleanings with a water rinse between each No. 113 cleaning. The water rinse should consist of wetting a cloth with clean water and wiping the surface to remove loosened dirt and detergent. The final step should be to use a cloth dampened with isopropanol and wipe the mat to remove any organic contamination as well as the residual detergent. Avoid using excessive isopropanol because the bottom foam layer will absorb the solvent and cause the mat to swell. Regardless of the technique used to clean the mats, the previously described resistance measurement should be performed to verify that the mat is functional. Note: Read all Health Hazard, Precautionary, and First Aid statements found in the Material Safety Data Sheet (MSDS) and/or product label of cleaning materials prior to handling or use. Reference: 1. D. M. Yenni, Jr. "Basic Electrical Considerations in the Design of a Static-Safe Work Environment", Proc., (NEPCON/WEST), March 1979, pp. 273-284. 2. J. R. Huntsman, D. M. Yenni, Jr., "Test Methods for Static Control Products", Proc., EOS/ESD Symposium 1982, pp. 94-109. NFPA 56A Electrode Table Mat Megohmmeter Ground Connection Important Notice All statements, technical information, and recommendations related to 3M's products are based on information believed to be reliable, but the accuracy or completeness is not guaranteed. Before using this product, you must evaluate it and determine if it is suitable for your intended application. You assume all risks and liability associated with such use. Any statements related to the product which are not contained in 3M's current publications, or any contrary statements contained on your purchase order shall have no force or effect unless expressly agreed upon, in writing, by an authorized officer of 3M. Warranty; Limited Remedy; Limited Liability. This product will be free from defects in material and manufacture for a period of one year from the date of purchase. 3M MAKES NO OTHER WARRANTIES INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. If this product is defective within the warranty period stated above, your exclusive remedy shall be, at 3M's option, to replace or repair the 3M product or refund the purchase price of the 3M product. Except where prohibited by law, 3M will not be liable for any loss or damage arising from this 3M product, whether direct, indirect, special, incidental or consequential regardless of the legal theory asserted. 3 Electronic Handling & Protection Division 6801 River Place Blvd. Austin, TX 78726-9000 http://www.3M.com/ehpd Litho in USA. 40% Pre-consumer waste paper 10% Post-consumer waste paper (c) 3M IPC 1999 98-0798-0949-1(3-5-1.0)TR