Intek RheoVac 940 - Manual (Page 18)

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Table III. Process Variable Definitions and 4-20 mA Range
PROCESS VARIABLE
4-20 mA
FULL
SCALE
VALUE
PROCESS VARIABLE DEFINITION
ACTUAL VOLUME FLOW
[ACFM]
5000
The actual volumetric flow rate of gases leaving the condenser. It is a
measure of exhauster capacity. Decreased capacity means pump
degradation.
TOTAL MASS FLOW
[lbs/hr]
10000
The total mass flow rate of the flowing gas. Note: this value is not a
measure of air in-leak. It is a measure of steam jet ejector capacity.
WATER VAPOR MASS FLOW
[lbs/hr]
8000
The water vapor component of the flowing gas being removed from the
condenser.
RheoVac PRESSURE
[" Hg]
30
Absolute pressure at the RheoVac probe head. Should be equal to or less
than turbine back pressure.
WATER VAPOR SPECIFIC
VOLUME [cu. ft/lb]
10000 The inverse density of the water vapor present in the line.
WATER to AIR MASS RATIO 20
Ratio of water vapor flow rate to dry air flow rate. Defines “vacuum
quality.”
RELATIVE SATURATION
[%]
100
The percent concentration of water vapor in the extraction line relative to
saturation.
PARTIAL PRESSURE, WATER
["Hg]
10 The partial pressure of water vapor in the vacuum line.
AIR IN-LEAK
[SCFM]
100
Actual measure of air volume flow rate passing the RheoVac sensor head,
normalized to standard conditions (70°F, 29.9" HgA).
RheoVac TEMPERATURE
[°F]
210 Temperature of the flow media at the RheoVac probe head.
3.4 IBM-PC SOFTWA RE
IBM-PC Windows 95 compatible software has been provided. This software performs four primary
functions. It allows the user to:
• access data stored inside the RheoVac monitor over the last 24 hours
• chart all ten process variables from the RheoVac serial output (transmitted by means of
RS-232 or RS-422)
• archive the data into a general spreadsheet format
• change the line size stored inside the instrument for mass and volume flow calculations.
The best way to archive RheoVac data is with a dedicated PC or DCS serial channel. However, RheoVac
software allows data from the last 24 hours to be downloaded to a PC file. This data is stored internally
in the RheoVac instrument. The data format is TAB delimited and is easily imported to spread sheet
programs. Column headers are included in the file and are defined in Table IV. There are two additional
columns which are not shown in the table. These two columns pertain to factory calibration and
diagnostics. They are for factory use only. For continuous archiving, a computer capable of running
Windows 95 software is required. The 24-hour instrument internal record is mainly a backup for
troubleshooting or for daily data collection when continuous control room recording is not available.
3.4.1 SOFTWARE INSTALLATION