Rosemount 890, Инструкция по эксплуатации

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U
NPACKING AND
I
NSTALLATION
Rosemount Analytical 748460-A January 2000
2-6
4. Check for bubbling or foaming which indicates leakage and repair as required. Any
leakage must be corrected before introduction of sample and/or application of
electrical power.
Note
Do not allow test liquid to contaminate cell or detectors and UV source
windows. Should this occur, follow instructions in subsection 6.1 to clean the
cell.
2.9 SAMPLE FLOW RATE
Recommended sample flow rate is 1 to 2 SCFH (500 to 1000 cc/min). A subnormal
flow rate will not affect readings but may result in an undesirable time lag. However,
an excessive flow rate can result in cell pressurization.
Assume that two cell volumes are required to flush any cell. Approximate flushing time
for the Model 890's 12-inch cell at atmospheric sampling pressure (i.e., the outlet of
the cell venting to atmosphere) is approximately 12 seconds.
Flushing time is inversely proportional to flow rate.
The primary effect of flow rate, other than flushing time, is cell pressure. Due to
restrictions in exit flow configuration, an increasing flow rate increases sample
pressure in the cell.
In all cases, the effect of pressure on readout is eliminated if the same flow rate is
used for the measured sample as well as for the zero gas and span gas.
Note that at higher flow rates the nonlinearity of the calibration curve increases,
because of increase in sample cell pressure. Therefore, if higher flow rates are
required, the calibration curve should be redrawn at the higher rate.
At flows up to 2 CFH (1 L/min), gaseous sample temperatures are equilibrated to
instrument temperature regardless of stream temperature. At extremely high flow
rates, this may not be true, but no such effect has been noted up to 18 CFH (9 L/min).
2.10 OPTION BOARDS
The following option boards may be ordered factory installed or may be ordered as kits
from the factory at a later date: Alarm, Calibration Gas Control, Auto Zero/Span and
Remote Range I/O. The boards are equipped with mating plugs for field wiring
attached to the connector at the edge of each board. Attach the cable (customer
supplied) to the plug and socket connector according to the schematic for each option
board.
If an option board has been ordered installed at the factory, this board will be inserted
into one of five slots inside the rear of the analyzer. Each option will require a cable
(user-provided) which connects to a female plug. The female plug, in original
packaging, is attached to the appropriate terminal block on the option board. If the
instrument came equipped with one option, the interconnect cable will be in place for
all options.