Patent ID: 8692648

Claim:
A system for monitoring or controlling equipment in a hazardous area, the system comprising: at least one sensor disposed within a hazardous area, each sensor being non-electrical and being adapted to interact with the equipment and generate at least a first non-electric sensor output and a second non-electric second sensor output, the first sensor output being indicative of a first equipment state and the second sensor output being indicative of a second equipment state; a non-electrical communication link extending from the at least one sensor across a boundary between the hazardous area and a non-hazardous area, the non-electric communication link to carry the sensor outputs from the at least one sensor; at least one controller disposed in the non-hazardous area, the at least one controller coupled to the communication link and operable to generate a controller output signal based on the sensor outputs; and a lift comprising first and second scissor lifts, a respective valve connected to each scissor lift, the respective valves on each scissor lift being pneumatically linked to at least one converter, the converter being adapted to provide an equalization converter output signal to the controller, the controller being adapted to equalize the positions of the first and second scissor lifts in response to the equalization converter output signal.