Met One Instruments C-12, Руководство по эксплуатации, Страница: 34 / 41

Page 34 C-12-9800 Rev A
7.4 Flow Audit and Calibration
The C-12 has a system of calibration menus which allow the operator to audit or calibrate various
system parameters for optimal performance. It is recommended that airflow control parameters be
audited monthly and calibrated quarterly during continuous operation. The exact frequency may
vary depending on local conditions and the data validation requirements established by the
sampling program administrator.
Figure 7-1 The C-12 Calibrate Menu
The CALIBRATE MENU option is in the main C-12 menu. The CALIBRATE MENU is described
below:
7.4.1 Flow Sensor Calibration
The CALIBRATE FLOW screen is used for field audits or calibrations of the sample flow
measurement of the C-12. The leak status must be checked before performing any flow
calibrations. See Section 7.5 for more details on this prerequisite.
Flow calibrations require a traceable flow audit calibration device. The Met One Instruments, Inc.
Swift 6.0 and similar particulate sampler flow calibrators work well. Attach the flow meter to the C-
12 sample inlet. The nominal flow rate for the C-12 is 1 lpm. Flow calibration devices should be
selected accordingly.
Figure 7-2 The C-12 Flow Calibration Screens
All flow values are in Q
a
actual volumetric conditions.
The screen will first display the zero-flow mode with the pump OFF. The measured flow will be
displayed at the top of the screen.
Press the ZERO softkey to zero the flow sensor. Then press CONTINUE to proceed to the main
flow calibration screen and automatically turn the pump ON.
The SET POINT parameter is the target flow rate that the C-12 will attempt to maintain. The FLOW
parameter is the current flow reading from the C-12 flow sensor. The instrument should
automatically regulate to the SET POINT value within a few moments.
The DEFAULT softkey may be pressed to clear out all previous field calibrations and restore the
factory calibration for the sensor if difficulties are encountered.
The STANDARD field is where the correct flow value from the traceable flow meter should be
entered if the flow does not match within ± 5% of the traceable standard. To correct the FLOW
reading, enter the value shown on the reference meter in the STANDARD field (see Section 0) and
then press the CALIBRATE softkey. The FLOW value should change to match the STANDARD
value when the CALIBRATE softkey is pressed. The monitor will then attempt to regulate the
FLOW value to match the SET POINT.
FLOW: 0.00 lpm
ZERO CONTINUE
SET POINT: 1.00 lpm
FLOW: 1.00 lpm
STANDARD: 1.00
DEFAULT CALIBRATE