Alicat VC Series Volumetric Flow Controller - Manual (Page 10)

10
The MC Series Mass Flow Controller provides a multitude of useful flow data in one simple, rugged
device. The MC Series can have several screen “modes” depending on how the device is ordered. All
MC Series controllers have a default Main Mode, Select Menu Mode, Control Set Up Mode, Gas Select
Mode (the Gas Select Mode may not be available on controllers calibrated for a custom gas or blend),
Communication Select Mode, Manufacturer Data Mode and a Miscellaneous Mode. In addition, your
device may have been ordered with the optional Totalizing Mode (page 43). The device defaults to Main
Mode as soon as power is applied to the controller.
Main Mode
The main mode screen defaults on power up with the mass flow on the primary display. The following
parameters are displayed in the main mode as shown in Figure 6.
PSIA o C Set Pt.
+13.49 +22.73 0.000
MASS
SCCM
Air
+0.000 +0.000
Volume Mass Main
Figure 6. Main Mode Display, MC Series Flow Controller
The “MODE” button in the lower right hand corner toggles the display between modes.
Set Pt. – The set-point is shown in the upper right corner of the display. The set-point cannot be adjusted
from the main mode screen. For information on changing the set-point, see “Set”, page 13.
Gas Absolute Pressure: The MC Series flow controllers utilize an absolute pressure sensor to measure
the line pressure of the gas flow being monitored. This sensor references hard vacuum and accurately
reads line pressure both above and below local atmospheric pressure. This parameter is located in
the upper left corner of the display under the dynamic label “PSIA”. This parameter can be moved to
the primary display by pushing the button just above the dynamic label (top left). The engineering unit
associated with absolute pressure is pounds per square inch absolute (PSIA). This can be converted
to gage pressure (PSIG = the reading obtained by a pressure gauge that reads zero at atmospheric
pressure) by simply subtracting local atmospheric pressure from the absolute pressure reading:
PSIG = PSIA – (Local Atmospheric Pressure)
The flow meters use the absolute pressure of the gas in the calculation of the mass flow rate. For
working in metric units, note that 1 PSI = 6.89 kPa.