GATES BELTS, HOSES, AND APPLICATIONS
Friday, January 21, 2011
Minimum Diameters
Different belts have different dimensions. They also use different materials; for instance, the cord inside an A section V-belt is smaller than the cord inside a B section V-belt. While this larger cord gives a B section belt more power capacity, it also means that your sheaves have to be above a larger minimum size than an A section belt’s sheaves. This applies to all of our belt lines. The smaller section belts can use smaller diameter sheaves and sprockets. The same concept applies to backside idlers as well. Going below these minimums on either the inside, or the backside of the belts can have a significant affect on belt life. To find out what minimum diameter sheave, sprocket, or idler your belt needs, check out our Belt Preventive Maintenance Manual available for free at www.gates.com/catalogs Click on the hyperlink for Power Transmission Catalog Collection to get to the page where you can download it.
Tuesday, January 11, 2011
Belt Drives and Dissipating Static Charge Buildup
All types of belts can generate electrical charges while operating in belt drive systems. Factors such as humidity and operating speed influence the charge potential. With static charges present there is potential for arcing or sparking in flammable environments. Other possible issues may be found with material handling processes or sensitive electronics.
In order to minimize possible issues with static charge build up, V-belts are generally manufactured in conductive constructions (Predator and PowerRated belts are not static conductive), and rubber synchronous belts can be produced in conductive constructions on a made-to-order basis. Note that Poly Chain GT Carbon belts cannot be produced in a conductive construction. The Association for Rubber Products Manufacturers (ARPM; formerly Rubber Manufacturers Association) defines standards for static conductive belts in their bulletin IP-3-3.
Static conductive belts meeting the ARPM Standard IP-3-3 should have sufficient conductivity to prevent measurable static charge buildup, thus preventing static discharges. Belt drive systems operating in potentially hazardous environments, though, must be properly grounded. A continuous conductive path from belt to ground is necessary to bleed off static charges. This path includes a static conductive belt, a conductive sprocket, a conductive bushing, a conductive shaft, and conductive bearings, all along the path to ground.
In hazardous environments, additional protection should be employed to assure that there are no accidental static spark discharges. Unusual or excessive debris or contaminant on belt contact surfaces or sprocket grooves, for example, can reduce the ability of belts to conduct static charges into hardware. In addition, belt conductivity properties are known to decline over time from normal use. Static conductive brushes or similar devices should be employed to bleed off any residual static buildup that might remain around belts.
In order to minimize possible issues with static charge build up, V-belts are generally manufactured in conductive constructions (Predator and PowerRated belts are not static conductive), and rubber synchronous belts can be produced in conductive constructions on a made-to-order basis. Note that Poly Chain GT Carbon belts cannot be produced in a conductive construction. The Association for Rubber Products Manufacturers (ARPM; formerly Rubber Manufacturers Association) defines standards for static conductive belts in their bulletin IP-3-3.
Static conductive belts meeting the ARPM Standard IP-3-3 should have sufficient conductivity to prevent measurable static charge buildup, thus preventing static discharges. Belt drive systems operating in potentially hazardous environments, though, must be properly grounded. A continuous conductive path from belt to ground is necessary to bleed off static charges. This path includes a static conductive belt, a conductive sprocket, a conductive bushing, a conductive shaft, and conductive bearings, all along the path to ground.
In hazardous environments, additional protection should be employed to assure that there are no accidental static spark discharges. Unusual or excessive debris or contaminant on belt contact surfaces or sprocket grooves, for example, can reduce the ability of belts to conduct static charges into hardware. In addition, belt conductivity properties are known to decline over time from normal use. Static conductive brushes or similar devices should be employed to bleed off any residual static buildup that might remain around belts.
Tuesday, January 4, 2011
Power and Fan Speed for Belt Drive Conversions
The power required to drive a fan relates to the fan shaft speed as follows:
Initial_Horsepower/New_Horsepower = (Initial_Fan_RPM/New_Fan_RPM)^3
A small speed change can result in a substantial increase in power consumption. Therefore, this relationship should be considered when replacing a V-belt drive with a synchronous belt drive for energy savings.
To ensure that the fan speed does not increase, the design speed ratio should be based on a measured fan shaft RPM of the existing V-belt drive. This measurement can be made with a contact or a strobe tachometer.
Initial_Horsepower/New_Horsepower = (Initial_Fan_RPM/New_Fan_RPM)^3
A small speed change can result in a substantial increase in power consumption. Therefore, this relationship should be considered when replacing a V-belt drive with a synchronous belt drive for energy savings.
To ensure that the fan speed does not increase, the design speed ratio should be based on a measured fan shaft RPM of the existing V-belt drive. This measurement can be made with a contact or a strobe tachometer.