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.
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.
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.
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