The Series 648B and 648C Differential Pressure Transmitters are designed to be used with clean, dry air and other non-corrosive gases. Each unit features a push-activated zero function and an associated LED light indicator. With the convenient push-button, zero calibration can be performed without any additional equipment, which significantly reduces time and cost for users. The dual color LED indicates if the transmitter is at normal operation, overpressure, or in the process of zero calibration. The enclosure consists of a flame retardant plastic top cover and a stainless steel bottom plate for ruggedness. The pressure ranges vary from 0.1 in w.c. to 25 in w.c. unidirectional and 0.25 in w.c. to 5 in w.c. bidirectional. Series 648B comes standard with ±0.8% FS* accuracy, while 648C models are available in ±0.4% FS* accuracy for more demanding applications. Wiring time is reduced with the removeable terminal block. Each unit features a 2-wire 4 to 20 mA output that is fully protected against short circuiting and incorrect wiring.