Emerson Rosemount Analytical OPM 4000, Инструкция по эксплуатации

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Instruction Manual
IM-105-4000, Rev 1.3
October 2008
OPM 4000
3-2
Stack Exit Correlation
Computation
NOTE
The stack exit correlation is especially important to verify. If possible, all
dimensions should be verified by actual measurements.
Lx/Lt is the ratio of the inside diameter at the top of the stack to the inside
diameter of the stack where the instrument is located (Figure 3-1). If the ratio
is greater than 1.0, the exit opacity will be greater than the opacity at the
instrument location. The OPM 4000 uses this correction factor to calculate the
stack exit opacity. It is not practical to have an Lx/Lt factor much greater than
2.0 because the error of the instrument increases as Lx/Lt becomes greater.
Lx = inside stack diameter at stack exit.
Lt = inside stack diameter at the transmitter location.
Lf = flange to flange distance between the transceiver and retro reflector unit.
1. Measure and record Lx and Lt and compute the Optical Path Length
Ratio (OPLR).
2. Check that the calculated value and the OPLR found in the Factory
OPLR, are within ±2%, refer to "Zero/Span Calibration Check".
Example: A stack with a 120 in. (3048 mm) stack exit ID and a 120 in.
(3048 mm) pathlength.
3. Enter the exit diameter (Lx) and measured diameter (Lt) in the control
unit. Refer to Section 4: Operation, for info on using the control unit.
Figure 3-1. Lx and Lt Stack
Dimensions
OPLR = Lx
2*Lt
OPLR = 120
2*120 = 0.50
RETRO
REFLECTOR TRANSCEIVER
Lx
Lt
Lf
Stack
38450026
Note:
Transceiver and retro reflector are shown
without the optional weather covers.