Inlet seals are a critical component for ensuring a leak free seal at the base of a GC inlet. For those of you who are using standard inlet seals on Agilent or Thermo Trace instruments, Restek also offers an alternative known as the Dual Vespel® Ring seal. This seal features a Vespel® ring on each side and comes in the same finishes as the standard OEM style inlet seals (gold, steel, Siltek®). There are a few advantages to using the Dual Vespel® seals over the regular style seals:
Figure 1: Location of the gold dual Vespel inlet seal with the arrow pointing to the location of the outside of the liner. Notice the edge of the injection port making contact with the Vespel material.
No separate washer required:
Standard inlet seals require you to place down a spacing washer, followed by the seal in the reducing nut. With the Dual Vespel® seals, the built in Vespel® ring on the bottom serves as the washer. One less inlet component to deal with!
Requires less torque to seal:
The Vespel® ring on the top provides a softer surface than metal, which allows it to more easily form a seal with the bottom of the lower inlet weldment. You no longer have to tighten it so hard your whole GC shakes with that last heave! This also ultimately reduces variability between different operators.
Reduces damage to base of inlet weldment:
Because of the higher torque required with the standard seals and the metal on metal contact, you can eventually start to damage the bottom of your inlet weldment. This can lead to leaks, due to a failure to properly seal. In addition, the Vespel® material is outside of the liner, eliminating potential bleed and activity (See Figure 1).
Stays sealed over multiple heating and cooling cycles:
The Vespel® seal has a low thermal expansion coefficient, which helps it to stay sealed over multiple inlet heating cycles. Metal seals, if not torqued very tightly, can loosen up and introduce leaks.
Dual Vespel® seals are priced equivalently to their traditional counterparts, so switching will not increase costs.
We have had some customers complain about the seal sticking to the bottom of the inlet (which is another indication of how well this product works!) If this happens, removal is not difficult.
Figure 2: Dual Vespel Inlet Seals come in several different surface finishes.
Technical article: http://www.restek.com/adv009
Agilent Dual Vespel Inlet Seals: http://www.restek.com/catalog/view/5134
Thermo Dual Vespel Inlet Seals: http://www.restek.com/catalog/view/39954