UNATTENDED GAS CHROMATOGRAPHS

THERE IS A NEED FOR AN UNATTENDED GAS CHROMATOGRAPH THAT CANMAKE CONTINUOUS MEASUREMENTS OF CARBON DIOXIDE ON SURFACE BUOYS OR SHIPS OF OPPORTUNITY. AN INNOVATIVE REAL TIME, LOWPOWER, AND INEXPENSIVE SURFACE ACOUSTIC WAVE (SAW) RESONATOR-BASED GAS CHROMATOGRAPH IS PROPOSED THAT OFFERS THE UNIQUE FEATURES OF RUGGED CONSTRUCTION, SMALL SIZE, AND LOW POWER AND GAS CONSUMPTION. THE UNIQUE IMPLEMENTATION OF THE PROPOSED GAS CHROMATOGRAPH IS DESCRIBED, AND ITS POTENTIAL FOR REAL TIME UNATTENDED MONITORING IS FULLY ADDRESSED. THE DEVELOPMENT OF AN INSTRUMENT CAPABLE OF OPERATING FOR UP TO ONE MONTH UNATTENDED IS DESCRIBED. A PAIR OF SAW RESONATORS ARE PROPOSED WHOSE DIFFERENTIAL OUTPUT FREQUENCY WILL HAVE A DYNAMIC RANGE OF 106 AND A TEMPERATURE MEASUREMENT CAPABILITY OF 1/2400 DEGREES CENTIGRADE. THE ADVANTAGES OF THE PROPOSED APPROACH ARE: FIRST, THE REQUIRED CIRCUITRY IS MINIMAL AND LOW POWER; SECOND, THE SENSOR IS RUGGED AND INTERFACES EASILY WITH A MICROPROCESSORWITHOUT THE NEED FOR A/D CONVERTERS; THIRD, THE PROPOSED APPROACH HAS LOW GAS CONSUMPTION AND CAN OPERATE UP TO ONE MONTH UNATTENDED.