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• 19 •
2003 Volume 2
800-356-1688
By Donna Lidgett, GC Accessories Marketing Manager
Ensure a Leak-Tight Seal
the First Time, Every Time
Reliable, Leak-Tight Sealing
with Vespel® Ring Inlet Seals•
✔ End problems associated with leaks at the inlet seal.
✔ Prevent wear or damage to the critical seal.
✔ Try Vespel ® Ring Inlet Seals, free.
In Agilent split/splitless injection ports, the inlet seal
sits at the base of the injector (Figure 1). Dirt, non-
volatile residue, septum fragments, and other debris
can accumulate on the surface of the seal and skew
the linearity of your analyses. The only way to main-
tain optimum performance is to change the inlet
seal frequently. Each time you change the inlet seal
you must check the connection and ensure the seal
is leak-tight, to prevent column oxidation and other
problems associated with leaks.
Herein is a problem. It can be difficult to make and
maintain a good seal with a conventional, metal,
inlet disk. The metal-to-metal seal dictates that you
apply considerable torque to the reducing nut but,
based on our tests, this does not ensure a leak-tight
seal. And, even if the seal is good initially, metal-to-
metal seals are prone to leak over the course of
several oven temperature cycles, allowing oxygen
and water vapor to enter the system. This can oxi-
dize the phase in the capillary column, affect chro-
matogram baselines, and/or create other difficulties,
causing expense and downtime. Potentially a worse
problem, frequent making and breaking of the
metal-to-metal seal ultimately could wear or dam-
age the surface of the critical seal on the bottom of
the injector body.
For years, Restek has offered replacement inlet
seals for Agilent 5890, 6890, and 6850 split/splitless
injection ports. The design and construction of our
inlet seals prolong column lifetime - because oxy-
gen is less likely to leak into the carrier gas - and
reduce baseline noise from high-sensitivity detectors
(e.g., ECDs and MSDs). To lessen breakdown and
adsorption of active compounds, we offer inert
gold-plated and Silcosteel®-treated inlet seals, as
well as stainless steel seals.
Yet, we had not entirely eliminated the problem of
leaks. Now, Restek's instrument innovations team
has re-engineered the inlet seal to address this
issue. The solution, the Vespel® Ring Inlet Seal, is a
high-quality stainless steel seal with a soft, easy-seal-
ing Vespel® ring embedded into its face, eliminating
the unreliable metal-to-metal seal. While ensuring a
leak-tight seal, the Vespel® ring cannot harm the
critical seal, and is outside the sample flowpath.
Inlet maintenance becomes worry-free!
The Vespel® Ring Inlet Seal is designed to hold its
seal, even after repeated temperature cycles, without
retightening the reducing nut. To determine the dif-
ferences between conventional inlet seals and
Vespel® Ring Inlet Seals, we compared the leak rate
for several inlet seals of each type across a range of
torque, using a high sensitivity helium leak detector.
Figure 2 shows Vespel® Ring Inlet Seals performed
exceptionally at all levels, but especially well at
lower torque.
Like our conventional inlet seals, Vespel® Ring Inlet
Seals are available in stainless steel, gold-plated, or
with Silcosteel® treatment. Use the stainless steel
seals for analyses of nonactive compounds. To
reduce breakdown and adsorption of active com-
pounds, use gold-plated or Silcosteel®-treated seals.
The gold surface offers better inertness than stain-
less steel; Silcosteel® treatment produces inertness
similar to that of fused silica tubing.
Inlet Seal Qty. cat.# Price
0.8mm stainless steel 10 + 2* 21316-425
0.8mm gold-plated 10 + 2 21318-425
0.8mm Silcosteel® -treated 10 + 2 21320-425
1.2mm stainless steel 10 + 2 20391-425
1.2mm gold-plated 10 + 2 21306-425
1.2mm Silcosteel® 10 + 2 21308-425
*10 conventional metal inlet seals, 2 Vespel® Ring Inlet Seals.
Figure 2 — The Vespel® Ring Inlet Seal achieves a
leak-tight seal even at low torque, reducing the
chance of leak-related problems.
Leak Rate (Log
10 atm cc/sec.)
0 10 20 30 40
0.01
1E-3
1E-4
1E-5
1E-6
1E-7
1E-8
1E-9
1E-10
50 60
Vespel® Ring Inlet Seal
stainless steel
original equipment
inlet seal
Torque (in. lbs.)
Inlet seal
Figure 1
Ordering Information | Inlet Seals Special Offer!
Order a 10-pack of our conventional
metal inlet seals, receive a 2-pack of
Vespel ® Ring Inlet Seals, Free! FREE
Are you using conventional
inlet seals, but want to try
Vespel® Ring Inlet Seals?
Purchase a 10-pack of our
conventional inlet seals and we'll
include a 2-pack of Vespel® Ring
Inlet Seals, free. Use the special
catalog numbers below.
June 30 is the last day to take advantage of this offer!
•Patent pending.
Free Vespel® Ring Inlet Seals!
Hurry-
To maintain optimum
performance, the
inlet seal in an
Agilent GC should be
replaced frequently.