Land 4500 MKII Premier, Operation And Maintenance Manual

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Model 4500 Premier Dust and Opacity Monitor
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C1-4 Examples of Different Optical Pathlength Ratios (OPLR)
Straight stack.
Measurement pathlength and exit pathlength are equal.
PLCF = 1.00, OPLR = 0.50
Example 1
Straight stack, monitor on narrow duct.
Measurement pathlength is less than exit pathlength.
PLCF > 1.00, OPLR >0.50
Example 2
Stack narrows towards exit.
Measurement pathlength is greater than exit pathlength.
PLCF < 1.00, OPLR <0.5
Example 3