Intek RheoVac 950A - Manual (Page 18)

- 16 -
3.4 COMMUNICATIONS
Typical RheoVac 950 instruments have an Ethernet port, two serial communications choices
(RS-232 or RS-422) and optional eight 4-20 mA output signals for each probe. All 4-20 mA
output signals are linearly scaled such that 4 mA represents 0% of the rated full scale value
(except temperature, which is 0(C) and 20 mA represents 100% of the rated full scale value
(temperature is 100(C). The standard full scale values and definitions of all process variables
are listed in Table 3. Note: Intek recommends using the network connection for all data
transmissions and RheoVac communications. Communication with the RheoVac unit using Intek
supplied software is discussed in Appendix A of this manual.
Table 3 Process Variable Definitions and 4-20 mA Range*
PROCESS VARIABLE
4-20 mA
FULL
SCALE
PROCESS VARIABLE DEFINITION
ACTUAL VOLUME FLOW
ACFM [m 3 /hr]
5000
[8,500]
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 [kg/hr]
10000
[4,536]
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 total vapor and air removal and
exhauster operating capacity.
WATER VAPOR MASS FLOW
lbs/hr [kg/hr]
8000
[3,629]
The water vapor component of the flowing gas
being removed from the condenser.
RheoVac PRESSURE
” Hg [mm Hg]
30
[762]
Absolute pressure at the RheoVac probe head.
Should be equal to or less than turbine back
pressure.
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.
AIR IN-LEAK
SCFM [nm 3 /hr]
100
[169.9]
Actual measure of air volume flow rate passing the
RheoVac sensor head, normalized to standard
conditions (70°F, 29.9” HgA).
RheoVac TEMPERATURE
°F [°C]
212
[100]
4 mA = 0°C or 32°F, 20 mA = 100°C or 212°F
Temperature of the flow media at the RheoVac
probe head.
*See Custom Information section (Section 6) for custom units of measure.
3.5 DATA PROCESSING
A very important part of understanding your condenser system comes from evaluating the data
that is measured, created and stored by the RheoVac instrument. A data file is created for each
calendar day that the monitor is operating. The ability to review stored data has been invaluable
when troubleshooting condenser problems. The column heading for each archived data file is
seen in Table 4. Intek provides solutions for viewing and analyzing data.
Table 4 Column Headings for Data Downloads and Archived Data*
Time
Stamp
Actual
Vol.
Flow
(ACFM)
Total
Mass
Flow
(lbs/hr)
Water
Vapor
Mass
Flow
(lbs/hr)
RheoVac
Pressure
(“HgA)
Water
Vapor
Sp. Vol.
(ft 3 /lb)
Water
to Air
Mass
Ratio
(lb/lb)
Relative
Satura-
tion
(%)
H
2
O
Partial
Pressure
("HgA)
Air
Flow
In-Leak
(SCFM)
Probe
Temp.
(ºF)
RS
Temp.
(ºF)
Raw
Total
Mass
Flow
(lbs/hr)
¨T
(ºF)
RS
Out.
*See Custom Information section (Section 6) for custom units of measure.