Agilent Technologies Agilent 7890 Series, Maintenance Manual

Page: 338 / 354

338 Maintaining Your GC
19
Maintaining a Valve
To Replace a Gas Sampling Valve Loop
1 Gather the following:
• Replacement sample loop. (See “Consumables and Parts
for Valves” on page 336.)
• 1/4- inch wrench
• Vacuum cleaner
2
Load the GC maintenance method and wait for the GC to
become ready.
3 Turn off the detector.
4 Set all valve box valves to
Off
.
5 Leave on the GC and valve actuator air.
6 Turn off the carrier gas and sample line flows and relieve
any back pressure to the valve.
7 Remove the upper valve box. (See “To Remove the Upper
Valve Box” on page 344.)
8
Vacuum any loose particulate insulation.
9
When the valve is cool, loosen the sample loop’s two
1/4- inch fittings on the valve head and remove the loop.
WA R N I N G
The oven, inlet, detector, and valve box may be very hot.
Sample and/or harmful gases may be present. Refer to your
company’s standard operating procedures for purging the
chemicals from the sample line.
WA R N I N G
The valve box insulation is made of refractory ceramic fibers
(RCFs). To avoid inhaling RCF particles, we recommend these
safety procedures:
1. Ventilate your work area
2. Wear long sleeves, gloves, safety glasses, and a disposable
dust/mist respirator
3. Dispose of insulation in a sealed plastic bag
4. Vacuum any residual particles and discard
5. Wash your hands with mild soap and cold water after handling
RCFs.