STATIC electricity can easily be dismissed as a novel, harmless phenomenon. But in some fan applications its impact can be disastrous.
Static electricity is created by movement between non-conducting materials. In fans, this may even occur due to friction between an impeller blade and air molecules.
While this is not a problem with metal blades, static electricity can build up sufficiently in fans with plastic blades to create a charge.
A potential occurrence is an electrical arc between the blade tip and the metal fan case, presenting a high level of danger in a hazardous, explosive atmosphere.
Fantech has tackled this issue with the release of a new style impeller blade for adjustable pitch axial fans.
The impeller is anti-static, achieved by mixing carbon with the traditional Glass Reinforced Polypropylene (GRP) during manufacture.
"When it came to Hazardous locations, we traditionally offered customers the choice of using standard GRP or aluminum blades with a brass anti-spark ring," a Fantech spokesman said.
"The ring is fitted to the fan case around the impeller track as a form of insurance, to prevent sparking in the unlikely event of the fast-moving aluminum blade coming into contact with the steel fan case.
“However, the new anti-static impeller blade presents a safer, more cost effective solution to this problem. The carbon in the new impellers provides conductive characteristics thereby reducing the electrical resistance of the blade material. This prevents the build up of any static electricity charge within the blade."
At present anti-static blades are available for Fantech's 1000 Series Elta impeller, in a range from 315mm to 1000mm diameter.
The blades were independently tested in the UK. The test, Insulation Resistance of Polymeric Fan Blade, was conducted in accordance to BS EN 50014:1992 and a certificate of approval granted.