TD1/TD2/TD3/TD4/TD5 Needles and Seals
C14
Scientific Instrument Services, Inc.
TM
Phone: 908-788-5550
www.sisweb.com/catalog/08/C14
Seals for Desorption Tubes
Seals are utilized in a variety of locations in the Short Path Thermal Desorption Unit.
Graphite seals are physically soft but have excellent sealing properties and temperature limits and are recommended for most appli-
cations with the Desorption System. The graphite seals have good sealing properties when tightened finger tight, have a fairly good life,
and provide for the highest temperature without contamination of the system by foreign matter.
PTFE seals have temperature limitations like the VitonTM seals, but are good general seals for lower temperature applications. They
have good sealing characteristics, good abrasion resistance, and are usable to about 230°C. At temperatures above this they tend to flow
and then are quite difficult to remove from the fittings.
Graphitized Vespel
TM
seals contain 40% graphite and physically are harder than graphite seals but with lower temperature limits. They
require slightly more force to form a good seal in the Desorption Unit. Normally about 1/16 turn past finger tight will form a good seal.
Since these seals are harder than graphite, they hold their shape better, have a longer life, and are easily removable.
Seals for the Desorption Tubes
(Dimensions inches)
Cap
Top
Needle Accessory
Max.
Sealing
Units
Part No.
Type
O.D.
I.D.
Thick
Seal
Seal
Seal
Seals
Temp.
Properties
/ pkg
/pkg
PTFE Washer .21
.12
.06
X
X
X
X
230°C
G
10/pk.
Graphite Top Sealing Washer
.21
.06
.06
-
X
-
X
450°C
EX
1 ea.
Graphite Needle Washer
.21
.04
.06
X
-
X
-
450°C
EX
1 ea.
Grap Vesp Top Sealing Washer
.22
.06
.06
-
X
-
X
350°C
G
1 ea.
Grap Vesp Needle Seal Washer .22
.04
.06
-
-
X
X
350°C
G
1 ea.
Vespel Seal with Cartridge (TD5)
1 ea.
Desorption Tube & Connector Assembly for TD1-TD4
Connecting Tube and Needle Assembly for TD5
Needles for the Desorption Tubes
I
n the Short Path
TM
Thermal Desorption System, the needle serves as the transfer line for the introduction of the sample into the Gas
Chromatograph. This "short path" for sample transmission is the key advantage of the Short Path Thermal Desorption technology
which minimizes sample decomposition, eliminates system contamination and provides for the maximum delivery of samples to
the GC.
This 2 piece needle has been specifically designed for the AutoDesorb
TM
system and is now used for all models of the Thermal
Desorption System replacing the previous design. The new design will permit the sealing of the needles and connecting tube to the des-
orption tube with just a finger tight twist connection. Vespel
TM
seals (sold separately) are used to make the leak tight seal. Double seals
are not needed with this system. The needles are of the side port design to eliminate coring of the GC septa and are 35 mm long. The
needles are available in plain stainless steel and now also in Silco
TM
coated steel to eliminate any metal surface in contact with your sam-
ples.
For other style needles please call.
Part No.
Description
AutoDesorbTM Needle, 35 mm
AutoDesorbTM Needle, 35 mm, Silco
TM
Swagelok Fitting
Connecting Tube
GLT
Desorption
Tube
S.S. Needle Cap
Top
Sealing
Washers
Seal
with
Cartridge
Desorption
Tube
Vespel Seal
Part# 786018
Desorption
Tube Needle
2 Piece Desorption Tube Needle and Cross Section
Showing placement of the needle and seal.
tip...
