Rosemount Oxymitter 4000, Инструкционный бюллетень

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IB-106-340
6-20
g. Flowmeter Adjustments.
1. Calibration Gas Flowmeter. Calibration gas
flowmeter (17, Figure 6-13) regulates the
calibration gas flow and must be set to 5 scfh.
However, only adjust the flowmeter to 5 scfh
after placing a new diffusion element on the
end of the Oxymitter 4000. Adjusting the
flowmeter at any other time can pressurize the
cell and bias the calibration.
In applications with a heavy dust loading, the
O
2
probe diffusion element may become
plugged over time, causing a slower speed of
response. The best way to detect a plugged
diffusion element is to note the time it takes
the Oxymitter 4000 to return to the normal
process reading after the last calibration gas is
removed and the calibration gas line is
blocked off. A plugged element also can be
indicated by a slightly lower reading on the
flowmeter.
Change the diffusion element when the
calibration gas flowmeter reads slightly lower
during calibration or when the response time
to the process flue gases becomes very slow.
Each time the diffusion element is changed,
reset the calibration gas flowmeter to 5 scfh
and calibrate the Oxymitter 4000. For more
information on changing the diffusion ele-
ment, refer to paragraph 6-8.
2. Reference Air Flowmeter (Optional).
Reference air flowmeter (16, Figure 6-13)
regulates the reference air and must be set to
2 scfh. Adjust the flow with the knob on the
bottom of the reference air flowmeter when
necessary.
h. Flowmeter Replacement. Use this procedure to
replace either reference air flowmeter (16, Figure
6-13) or calibration gas flowmeter (17).
1. Turn off power to the system.
2. Shut off the calibration gases at the cylinders.
3. Loosen, but do not remove, four screws (13)
securing flowmeter bracket (25) to the
manifold.
4. Flex the bottom of flowmeter bracket (25)
downward and away to disengage and remove
from the manifold.
5. For reference air flowmeter (16), remove
pressure regulator (8) by disconnecting tubing
(11) from elbow fitting (10). Also, disconnect
tubing (24) from straight fitting (23).
For calibration gas flowmeter (17),
disconnect tubing (18) at elbow fitting (21).
Also, disconnect gas tubing (2) from elbow
fitting (15).
6. Remove screws (6) and bracket (5) securing
flowmeter (16 or 17) to flowmeter bracket
(25).
7. Remove flowmeter (16 or 17), with installed
fittings, from flowmeter bracket (25).
8. For reference air flowmeter (16), remove
elbow street fittings (14 and 22). It is not
necessary to remove fittings (10 and 23) from
the street fittings.
For calibration gas flowmeter (17), remove
elbow fittings (15 and 21).
9. Apply pipe thread sealant to the threads of top
fittings (22 or 21) and bottom fittings (14 or
15) and install fittings into new flowmeter (16
or 17).
10. Position flowmeter (16 or 17) into flowmeter
bracket (25) and secure with bracket (5) and
screw (6).
11. For reference air flowmeter (16), connect
tubing (11) to elbow fitting (10) and install
pressure regulator (9). Also, connect tubing
(24) to straight fitting (23).
For calibration gas flowmeter (17), connect
tubing (2) to elbow fitting (15) and connect
tubing (18) to elbow fitting (21).
12. Slide the top slots of flowmeter bracket (25)
onto screws (13). Flex the bottom of the
bracket downward and toward the manifold to
engage the bottom bracket slots and screws.
Tighten screws.
13. Turn on the calibration gases at the cylinders.