ADM Flow Meter
Principles of Operation
10
Agilent CrossLab CS ADM Flow Meter Operation Manual
Principles of Operation
The ADM flow meter provides continuous, real-time
measurements of dry gas flows, such as those used for gas
chromatography. Unlike bubble flow meters, the flow meter
operates without liquids, bubbles, or glass parts. When
activated, a solenoid actuated valve interrupts the gas flow
momentarily. The gas flow moves a diaphragm in proportion to
the flow rate. This movement is transformed by the flow
meter's electronics into a digital value, which is displayed on the
flow meter's screen. The flow meter provides two different
types of flow measurements: volumetric flow (mL/min) and
mass flow reported in standard cubic centimeters per minute
(sccm). Mass flow values are calculated from the volumetric
measurements by correcting for ambient temperature and
atmospheric pressure, and reporting the flow rate referenced to
0 °C and one atmosphere of pressure, using digital temperature
and pressure sensors installed in the mainframe of the
flow meter.
The flow meter uses a replaceable cartridge that contains all
parts subject to calibration. This eliminates the need to ship the
entire meter back to the factory to maintain its calibration. The
cartridge calibration is valid for a period of one year from its first
use. A new, calibrated cartridge can be ordered in advance, and
installed when necessary.
When the flow meter is powered on with a new cartridge
installed, the current date is written to the cartridge’s memory
based on the mainframe’s internal clock. Each time the flow
meter is turned on, the meter will compare the current date to
the initial turn on date of the cartridge. If the initial turn on date
is more than a year from the current date, the flow meter will
flash a notification to the user that the calibration has expired.
The flow meter will still function with an expired calibration. This
eliminates downtime, enabling you to keep working. See
Installing and Replacing the Cartridge
The flow meter is powered by three AA alkaline batteries. Power
can also be supplied via the micro USB port located on the side
of the unit.
