Yokogawa GC8000 Process Gas Chromatograph - Manual (Page 403)

<6. Maintenance>
6-50
IM 11B08A01-01E
(3) Flowmeter
(4) Pressure gauge
(5) Pneumatic valve for actuating external air supply
(6) Stream switching valve or pneumatic valve for atmospheric balance
(1) Sample Processing System
The sample processing system is a train of fi lter, regulator for samples, stop valve, stream
switching valve and needle valve.
Some systems may not comprise all of these components depending on the specifi cations. To
replace any of these components, follow the steps below.
(1) Stop the operation. (See “3.3.4 Stopping operation” for this procedure).
(2) Turn off the supply of the sample.
(3) If the sample is liquid, purge the sample line with the purge gas (nitrogen gas or instrument
air).
• When the stream switching valve is a pneumatic valve, change the analyzer status to
Manual and turn on the stream switching valve on the sample line to let the purge gas fl ow
in.
• When the stream switching valve is a stop valve, close all the stop valves and open the stop
valve on the sample line to let the purge gas fl ow in.
(4) Close all the stream switching valves.
IMPORTANT
• During the purge, purge gas may fl ow into the sample return line, causing pressure
fl uctuation.
Prepare the sample return line and collection tank, if necessary.
• Prepare the sample return line so that the sample does not return.
(5) Stop the supply of power.
CAUTION
The isothermal oven is extremely hot after turning off the power immediately. Keep the purging
air supplied for more than an hour after turning off the power. Keep hands away from the oven
components.
(6) Remove the two pipes connected to the needle valve shown on the far left of Figure 6.44.
(7) Remove the nut on the outside of the analyzer unit.
(8) Remove the sample processing system from the analyzer.
(9) Remove the component and install a new component.
(10) Reassemble the sample processing system in the reverse order of steps (7) to (9).
When installing a replacement component, always use sealing tape.
(11) Confi rm that there are no leaks in the piping.
K9193HH Needle valve
K9192WA Stream switching valve (Diaphragm: Tefl on, Wetted surface: Viton)
K9192WB Stream switching valve (Diaphragm: Tefl on, Wetted surface: Silicone)
2nd Edition : May 11, 2012-00