Ametek Land 4750-PM, Руководство пользователя

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User Guide 5 - 4
Particulate Measurement System 4750-PM
The Calibration Factor is applied to the value displayed. This reading is then
used by the analogue 4 to 20 mA output. To configure the sensor to provide
mg/m³ dust readings for a particular stack or duct see Calculating a new
Calibration Factor below.
Adjusting the Calibration Factor [CF] and Offset [OFF]
1) Scroll DOWN to CAL (Calibration) and press RIGHT to access the CF
(Calibration Factor) submenu.
2) Press RIGHT again to display the current CF (default: 1.000 ).
3. Use the UP/DOWN buttons to change the value. Press RIGHT to move to
the next digit.
4) Adjust the decimal point: after editing the fourth digit press RIGHT
again, the decimal point starts flashing. Use the UP/DOWN buttons to
adjust the position of the decimal point.
5) If required, repeat steps 2 through 3 to adjust the offset [ OFF ].
6) When complete, press RIGHT or LEFT repeatedly to return to the main
menu.
Calculating a New Calibration Factor
To calculate a new calibration factor [CF] that will allow correct configuration
of the dust reading to correspond to the actual mg/m³ reading in the stack,
use the formula below. Note that the instrument readings during the period
of an isokinetic sampling run need to be recorded, then calculate as follows:
new CF = current CF × (Sampling Result [mg/m³])
(Average Sensor Reading [mg/m³])
Note that this assumes that the offset [OFF] has been set correctly so that
the instrument reads ‘0’ mg/m³ in a dust-free environment.
5.2.5 4-20mA Output [4_20]
The 4-20mA settings menu [ 4_20 ] allows the span of the 4-20mA output
to be set. The Span value sets the relationship between the reading on the
display and the current output from the 4-20mA output.
Example: if the Span value is set to 100, then a display reading of ‘100’ will
output 20mA (=the Span value). Display values above 100.0 will be clipped
at 20mA. A reading of ‘0.000’ will always output a value of 4mA.
Changing the 4-20mA Span Settings [SPAN]
1) Scroll DOWN to the 4_20 and press RIGHT to access the menu. The
display shows the current Span value (default: 100 ).
2) Use the UP/DOWN buttons to change the value. Press RIGHT to move to
the next digit.
3) Press RIGHT to return to the main menu.
NOTE
The range of allowed values for span: the decimal point is fixed
after the 3rd digit; this allows displaying values ranging from
000.1 to 999.9.