4B has just launched an ATEX / IECEx / CCC approved version of its popular Milli-Speed, a loop powered 4 - 20 mA analogue output speed switch for PLC, DCS or stand-alone controllers.
The Milli-Speed switch is designed to detect belt slip, belt underspeed, stop motion, low speed or zero speed on bucket elevators, conveyors, airlocks, mixers, fans, grinders and many other rotating machines.
An inductive sensing device located in the nose of the Milli-Speed enclosure will detect a ferrous metal target. This target can be an existing bolt head or device attached to a shaft, such as 4B’s Whirligig® sensor mount. During installation, the Milli-Speed is set to the machine’s normal running speed by simple magnetic calibration. The 4 - 20 mA output signal is automatically scaled for zero to full speed with over speed detection.
The Milli-Speed is fully encapsulated in a polycarbonate body that is corrosion and abrasion resistant, dust-tight and waterproof (IP67). Its approvals for explosive atmospheres include: ATEX, IECEx and CCCEx; Zones 20, 21 & 22 for dust and Zones 0, 1 & 2 for gas.
Additionally, 4B’s SpeedMaster™ can be used with the Milli-Speed to test the functionality after the initial installation and during routine maintenance procedures. The SpeedMaster™ is the only device that accurately tests the calibration of a speed switch, and allows testing of the alarm and shutdown features of the sensor while installed on the machine shaft.