Alicat VC Series Volumetric Flow Controller User Manual

Page 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

Comm. Mfg.

RS-232 Data Menu

Figure 7. Select Menu Display