Circuits and methods for protecting thyristors in a bridge configuration are provided. Register R0 provides filter coefficients to the filter operation circuit. The urethane-substituted xanthene colorant features very good wax andor oil solubility, and is believed to be relatively nontoxic. The plurality of wireless routers is capable of receiving emissions data received from the plurality of wireless sensor units and routing the emissions data received from the plurality of sensors to the set of wireless gateways.