Deprag were approached by a VAT drainage equipment manufacturer to supply a 1,200W pneumatic brake motor, approved for use in an explosive environment.
A brake motor would be a nice solution to hold the VAT in place for safety reasons, and it would have to be ATEX approved because the equipment provides vat drainage of toxic powder materials with grains smaller than 100 µm, a bulk weight of 0.86 kg/l and ignition energy of less than 20 mJ.
Up until now there was no off the shelf solution, and the only alternative would be a complex custom built system.
DEPRAG engineers developed an entire system with the exposed parts made out of stainless steel, consisting of motor, brake assembly and gears. It corresponds with ATEX standards. This motor technology is now available as a standard product.
Wilfried Beer, managing partner of Beer Fördertechnik speaks enthusiastically of the immense advantages of this new type of brake motor. “By using this complete system for my vat drainage equipment, I can save myself enormous additional construction and manufacturing expenses because the brakes, which provide the safety for my mechanism, are already integrated.”
The integrated brake, which acts as a holding brake, is comprised of three brake disks, a pressure spring and a piston. They are controlled separately using an airline. When the control line has a pressure of over 5 bar the brake is released. If the pressure drops below 5 bar it is engaged.
Here is the difference. A normal brake has a grey area, where if the control line pressure is close to the compression force of the spring the brake can slip which would cause dangerous levels of heat, thereby elevating the risk of explosion in a hazardous area.
To produce a motor, which could be authorized for use in potentially explosive environments, DEPRAG engineers had to think outside the box. Mr Gerd Zinn, Manager of the Serial Machine Development Department said: “By implementing a safety valve, we have minimized this risk.” The valve turns the air feed off automatically when the pressure falls under 5-bar, causing the pressure applied to the brake to become zero. The brakes are then forced together fully and the motor is blocked.
The new motors are now available in various torque ranges and speeds in the 200, 300 & 1.2 kW stainless steel motor program from DEPRAG. They comply with ATEX guidelines.