Dry-test meter

Dry column chromatography 494 Dry packing, columns (LC) 349 Dry test meter 843 Dual oven (GC) 62 Durapak phases (GC) 125 Dwell time, gradient elution, (LC) 489, 563... 

Dry Test Meter Measures the total integrated volume of air sampled over a given time. The volume flow is measured by mechanical displacement of an internal bellows by the air flow. The displacement is recorded on a mechanical counter via a series of levers (accuracy 2-4%). 

In addition, an interesting phenomenon was observed when pumping the sample gas through the sampling probe. The chamber air is pulled through the screens and filter, and through a dry test meter with a Metal Bellows pump. When pump is on, a steadily increasing number of detectable condensation nuclei is found. 

Figure 8.5. Schematic diagram of pilot-scale supercritical CO2 processing system. 1. anhydrous milk fat (AMF) flow meter 2. AMF pump 3. CO2 pump 4. CO2 loop 5. flow loop 6. entrainment vessels 7. view cell 8. separator 1 9. separator 2 10. separator 3 11. separator 4 12. CO2 meter 13. dry test meter (Reproduced with permission from Bhaskar et al., 1993).

The product gas passed through a cyclone that captured fine catalyst particles and any char generated in the reactor, then two heat exchangers to remove excess steam. The condensate was collected in a vessel whose weight was continuously monitored. The outlet gas flow rate was measured by a mass flow meter and by a dry test meter. The concentrations of CO2, CO, and CH in the reforming gas composition were monitored by a non-dispersive infra-red analyzer (NDIR Model 300 from California Analytical... 

Liquid feeds (i.e., 1-hexene or xylene and xylene-ethylbenzene mixtures) were fed to the reactor by syringe pump through a preheat zone to insure complete vaporization and mixing, prior to entering the catalyst bed. Reactor effluent, was cooled via cold water trap to collect condensable liquid products while gaseous product volumes were monitored by standard dry test meter. Both gas and liquid products were analyzed by gas chromatography. 

The dry-test meter and the wet-test gas meter are volume-measuring devices. A set of plastic bellows is alternately filled and emptied, thereby driving the dial points via a system of bell cranks very little pressure is required. A thermometer and manometer are provided with the meter, for temperature and pressure corrections. Dry-test gas meters are useful for large-volume measurements. The wet-test meter is generally more accurate that the dry-test meter for smaller volumes. The gas drives a rotor, which in turn drives the meter. The meter housing is partially filled with water through which the rotor turns. It is calibrated by the manufacturer at a given level of water. 

Values of m/n for various test gas mixtures were determined in exactly the same way as for pure hydrocarbons. The test gas flowrates were calculated by using a flowrate conversion factor computed on the basis of known test gas composition (ref 7). These computed flowrates were in agreement with the values obtained by direct measurements with a positive displacement dry test meter. The results for the various test gas mixtures are summarized in Table V. 

TABLE III. COMPARISON OF DRY TEST METER AND THERMAL MASS FLOWMETER FLOWRATES IN THE RANGE OF 500-1500 seem... 

Test Gas Dry Test meter Flowrates, seem, measured by Thermal mass Flowmeter ... 

Errors in the dry test meter flowrates are based on uncertainties in the time required for the flow of preset volumes. Errors in the mass flowmeter flowrates represent 1 percent of the full scale of the meter (Full scale=1000 seem). 

---