Alicat VC Series Volumetric Flow Controller - Manual (Page 11)

11
Gas Temperature: The MC Series flow controllers utilize a temperature sensor to measure the line
temperature of the gas flow being monitored. The temperature is displayed in engineering units of
degrees Celsius (°C). The flow controllers use the temperature of the gas in the calculation of the mass
flow rate. This parameter is located in the upper middle portion of the display under “°C”. This parameter
can be moved to the primary display by pushing the top center button above “°C”.
Volumetric Flow Rate: The volumetric flow rate is determined using the Flow Measurement Operating
Principle described on page 27. This parameter is located in the lower left corner of the display over
“Volume”. This parameter can be moved to the primary display by pushing the “Volume” button (lower
left). In order to get an accurate volumetric flow rate, the gas being measured must be selected (see
Gas Select Mode). This is important because the device calculates the flow rate based on the viscosity
of the gas at the measured temperature. If the gas being measured is not what is selected, an incorrect
value for the viscosity of the gas will be used in the calculation of flow, and the resulting output will be
inaccurate in direct proportion to the ratio between the two gases viscosities.
Mass Flow Rate: The mass flow rate is the volumetric flow rate corrected to a standard temperature
and pressure (typically 14.696 psia and 25°C). This parameter is located in the lower middle portion
of the display over “Mass”. This parameter can be moved to the primary display by pushing the button
located below “Mass” (bottom center). The controllers uses the measured temperature and the measured
absolute pressure to calculate what the flow rate would be if the gas pressure was at 1 atmosphere and
the gas temperature was 25°C. This allows a solid reference point for comparing one flow to another.
Flashing Error Message: Our flow meters and controllers display an error message (MOV = mass
overrange, VOV = volumetric overrange, POV = pressure overrange, TOV = temperature overrange)
when a measured parameter exceeds the range of the sensors in the device. When any item flashes
on the display, neither the flashing parameter nor the mass flow measurement is accurate. Reducing
the value of the flashing parameter to within specified limits will return the unit to normal operation and
accuracy.
Select Menu Mode
Pushing “Mode” once will bring up the “Select Menu” display. Push the button nearest your selection
to go to the corresponding screen. Push “Mode” again to return to the Main Mode display. ( Note: If
your controller was ordered with Totalizing Mode option (page 43), pushing the “Mode” button once will
bring up the “Totalizing Mode” display. Pushing “Mode” a second time will bring up the “Select Menu”
display.)
Gas Control Misc
Select Setup
SELECT
MENU
Comm. Mfg.
RS-232 Data Menu
Figure 7. Select Menu Display