9 RANGE GAS MIXTURE ANALYZER MODEL 6900
The Model 6900 is designed for the measurement of gas mixtures produced in the industrial gas industry. The analyzer is designed to quickly (3 - 5 minutes) analyze a gas cylinder, without the use of calibration standards, wet chemicals, or special knowledge of gas analysis instrumentation. The analyzer is designed so that it may be used directly in the cylinder-filling environment.
Valid over 50º F to 90º F(10ºC to 32ºC) ambient temperature conditions.
MINIMUM/MAXIMUM OPERATING TEMP.
40ºFto 100ºF (4ºC to 38ºC)
95% in 45 sec. for typical gas mixtures
Reference Gas: Commercial grade argon or nitrogen (depending upon the base gas range used) is required to flow continuously at 0.5 SCFH during analysis.
FREQUENCY OF CALIBRATION
Calibration is recommended once a year when used under spot-checking conditions; if run continuously will depend on conditions and range.
WARM UP TIME
8 minutes under room temperature conditions
Size: 9". high, 11". wide, 14". deep (23 cm X 28 cm X 35.5 cm),
Sea level to 2000 ft. (Altitude above 2000 ft. will cause some inaccuracy; consult the factory)
Current: 4-20 mA, proportional to gas analysis range selected (available on all ranges). The 4-20 mA resolution equals display resolution of 0.1% gas analysis.
PRINCIPLES OF OPERATION
Each gas has the ability to conduct heat at a specific rate. This is known as the thermal conductivity of the gas. This property is utilized in the Thermco thermal conductivity detector. Heated metal filaments are exposed to the zero and sample gases. The amount of heat carried away by the gas changes the rate of cooling of the wire filament and therefore, its temperature change. This temperature change causes a resistance change. Since the filaments are arranged in a Wheatstone bridge, the resistance change can be converted to an electrical current that is read out on a meter.
The user may encounter a gas mixture pair other than the nine standard ranges built into the analyzer. In this case, the user may perform an analysis by inputting his own calibration data into the analyzer. This can be accomplished by utilizing the push buttons on the front meter. Guidance is available from the factory concerning the thermal conductivity response of a wide variety of gas pairs.
3 GAS MIXTURES
Although the Model 6900 is not normally intended to measure a 3-part mixture, mixtures of Ar / CO2 / O2may be approximately measured if the user knows the oxygen level in the mix. Contact Thermco for details.
Thermco has been providing service for their analyzers since 1951. The Thermco repair department can normally complete repairs in two weeks.
The Model 6900 is not intended to measure oxygen/nitrogen mixtures for breathing air, oxygen purity, or other medical applications.
Along with the analyzer are supplied two 10 ft. lengths of tubing to run from the ports on the Model 6900 to cylinder regulators.