For plain METU-FORM ducts and fittings assembled with MUX overcollars, the equipotential bonding is only achieved when the MUX overcollar version with contact band is properly installed.
MUX Overcollars with "contact band" can be purchased from us. A contact band can also be created from scrap material and installed onto standard MUX overcollars according to the following instructions:
In some ductwork installations it is important to avoid any ignition sparks and other discharges. In order to achieve this an equipotential bonding is required throughout the ductwork parts.
Since the NBR gasket of the MUX overcollar is relatively hard, it is not guaranteed that the overcollar metal edges will touch the ducts in order to create the desired equipotential bounding.
For this reason a special contact band must be installed on the MUX overcollar according to the following instructions:
Contact Band made of the same metal as the MUX overcollars (galv. steel or stainless steel).
A = min. 120 mm, max. 130 mm
B = min. 9 mm, max. 13 mm
C = between 0,5 and 0,8 mm
Use your MUX overcollar as template to bend the edges of the contact band. Make sure that the folded ends are at least 10 mm long and wrap them around as shown.
Finally install the MUX overcollars around the ducts and check with the proper equipment that the equipotential bounding has been successfully achieved (resistance should normally be less than 0,1 Ohm).
The contact band is apparent when installed on the MUX Overcollar, thus allowing a visual control.
For the following METU-FORM products the equipotential bonding is uncertain or might not be possible at all unless the various parts are connected together with an appropriate cable in order to achieve an electrical continuity: