Replacing a Broken Transfer Line on 7697A Headspace Sampler

Answer

This Information Applies To: Agilent 7697A Headspace Sampler

Issue

The transfer line will need to be replaced if it breaks at the valve, the inlet or in the middle of the transfer line. The previously broken liner will need to be removed and new one installed. You may experience leak-like symptoms or poor/no chromatography.

Items required

• 3/16- inch open end wrench
• Column cutting wafer
• 1/4- inch open end wrench
• Wrench, angled, septum nut (GC inlet wrench)
• Polyimide ferrule corrected sized for the installed column (or, use a new 1/16- inch internal reducer union)
• 30 µm, 250 µm, or 320 µm fused silica column or ProSteel Column (at least 1.2 m length) 
• 11- mm septum for GC inlet
• Septum nut adapter (G3452- 60835)
• Ferrule preswage tool
• Isopropanol
• Lab wipe
• Lint-free gloves

Steps to Follow

Removal of the old transfer line from the GC inlet and valve assembly

1. Cool the GC inlet, GC oven transfer line, and valve assembly to safe handling temperatures before disassembly.
2. Press [Tray Park/Carousel Advance] to "park" the tray (if available)
3. Turn of all gas flows at the source and turn off both the GC and headspace sampler
4. Use a 1/4-inch wrench to loosen the XLSI transfer line nut 
5. Unlatch and open the clamp on the transfer line interface accessory.
6. Gently lift the transfer line out of the inlet 
7. Remove the Pneumatics front cover by loosening the T-20 Screw that secures the cover in place and slide the cover out and lift to remove.
8. Carefully lift the valve thermal enclosure straight up. (See Figure 1)

   
   
   Figure 1. Thermal enclosure
   
   

9. Remove valve cover by loosening the two T-20 captive screws. (See Figure 2)
   

   
   
   Figure 2. Removing the valve cover
   1. Valve cover
   
   

10. Loosen the 3/16- inch nut in the internal reducer, it will be installed in valve port 3 at the 10 O'clock position (see Figure 3)
    

    
    
    
    Figure 3. Location of the Internal reducer for the transfer line
    
    

11. Remove the fused silica column or ProSteel column from the internal reducer.
12. Hold the transfer line by the mounting bracket and remove the fused silica or ProSteel line in one piece or multiple pieces
    

     

    Tips: If a section is stuck, you can use compressed air to blow it out or thread a ProSteel line through carefully to push out the broken liner pieces

Installation of fused silica tubing or ProSteel tubing

1. Select the appropriate tubing for method and thermal temperatures
2. Cut the tubing to approximately 1 m in length using a precision tubing cutter
   

    

   Tips: If utilizing ProSteel and intend to operate the transfer line over 200 °C or higher, then you must utilize the protective sleeve. Slide the protective sleeve over the tubing before installing into transfer line

3. Carefully thread the transfer line tubing into the transfer line trying not to bend and break the transfer line tubing on installation 

Installation of the transfer line into the valve

1.  Assemble the 3/16- inch nut and polyimide ferrule onto the fused silica tubing. (See Figure 4). Polyimide ferrule is easy to loose off the end of the fused silica tubing before installing it into reducer.
   
   

   
   
    Figure 4. Polyimide ferrule and fitting. 
   1. 3/16 - inch nut, 2. Tubing, 3. Polyimide ferrule
   
   

2. Install the transfer line into the 1/4 - inch nut using the 3/16- inch internal reducer. (see Figure 5). 
   If possible, leave the existing 1/4- inch nut and ferrule in place and install the new fused silica into it using a new ferrule and the existing 3/16- inch nut.
   Gently slide the fused silica tubing into the internal reducer until it bottoms. Tighten the 3/16- inch nut finger tight, then an extra 1/4- turn. Test the connection by gently pulling on the transfer line. The transfer line should not slide out of the internal reducer. 

   
   

   
    
   Figure 5. Installing the transfer ling fitting into the reducer 
   1. 3/16 - inch nut, 2. 1/4 - inch nut, 3. 1/16 - inch nut, 4. Polyimide ferrule, 5. Stainless steel ferrule
   
   

To prepare the GC interface end of the transfer line

1. Pass the transfer line fused silica tubing through the XLSI transfer line nut, flexible metal ferrule, and ferrule preswage tool. (See Figure 6). With the XLSI transfer line nut tight against the transfer line, hold the nut with a 1/4-inch wrench, and thread the ferrule preswage tool onto the nut.
   

   
    
   Figure 6. XLSI transfer line nut preswaging 
   1. XLSI transfer line nut, 2. Flexible metal ferrule, 3. Transfer line (Fused Silica or ProSteel), 4. Ferrule preswage tool
    

2. Using the 1/4-inch wrench and ferrule preswage tool, tighten the nut a little at a time, occasionally checking to see if the ferrule is gripping the tube.
3. When the ferrule just starts to grip, notice the position of the nut and then tighten by turning 45 to 60 degrees of rotation, but no more than 60 degrees (one flat). If you can pull the column free, it is not tight enough.
4. Remove the ferrule preswage tool.
5. Using a ceramic column cutter, trim the tubing at the small end of the ferrule, leaving approximately 0.3 mm of tubing extending beyond the ferrule.
   

    

   Tips: It is important that the ceramic column cutter has one side dedicated to only making contact with the column and the other side dedicated to riding on the edge of the flexible metal ferrule. This preserves the ceramic edge sharpness, which is necessary for making good column cuts.

6. Check the end of the tube with a magnifier. The end of the tube needs not to be perfectly square, but should not have cracks extending under the ferrule.

Attach the transfer line to the accessory

1. Unlatch and open the clamp on the transfer line interface accessory.
2. Carefully place the transfer line end-cap into the clamp on the transfer line interface accessory. The end-cap should lie squarely against the bottom and back surface.
3. Partially latch the clamp, closing it enough to loosely secure the transfer line and end-cap. This provides strain relief, and aligns the end-cap to the heated block portion of the transfer line interface accessory.
4. Carefully thread the XLSI transfer line nut into the transfer line interface accessory fitting while keeping the transfer line end-cap aligned with the fitting.
5. Finger tighten the XLSI transfer line nut on the end of the transfer line, screwing it into the transfer line interface accessory fitting.
6. Completely latch the clamp. (See Figure 7)
   
   

   
    
   Figure 7. Completely assembled transfer line into Split/Splitless Inlet
   1. Transfer Line, 2. Clamp, 3. Support bracket, 4. Knurled thumbscrew
   
   

7. Use a 1/4-inch wrench to tighten the XLSI transfer line nut by 1/2 a flat (30 degrees)

Confirmation: Utilize leak and restriction test to verify that system is leak free before performing test injection.

Learn how to effectively maintain your 7697A Headspace Sampler : SI-7697-2100sV3 - Agilent 7697A Headspace Sampler Operation and Maintenance e-learning course available from Agilent education