GC Ferrules & Sealing Rings (Catalog D16)

GC Ferrules & Sealing Rings

D16

Phone: 908-788-5550

www.sisweb.com

A wide variety of materials are utilized for ferrules for use on gas

chromatographs. The chromatographer must determine the type of

ferrule to use based on the properties of the ferrule material and the

chromatography conditions.

Scientific Instrument Services™ provides

a wide selection of ferrules manufactured by SGE, TALU and SIS.

A summary table of the properties of each type of ferrule appears below:

Material

Temp. Limit

Sealing Properties

Strength

Reusability

Temp. Cycle

Graphite

450°C

Excellent

Poor

Good

Excellent

Graphitized Vespel

300°C

Good

Excellent

Excellent

Excellent

Vespel™ 350°C

Good

Excellent

Excellent

Excellent

PTFE

250°C

Excellent

Fair

Good

Poor

Glass-Filled PTFE

250°C

Excellent

Fair

Good

Fair

Silicone

‘O’ Rings

230°C

Good

Fair

Poor

Fair

Ferrules For Gas Chromatographs

Dimensions of fused silica capillary columns

(I.D. vs O.D.) for selection of ferrules

•

Graphitized Vespel may shrink and loosen at

subambient temperatures.

•

Graphitized Vespel will expand and shrink with

changing temperature. Connections should be

retightened a few times when first installed until

the ferrule has settled.

•

Graphite absorbs organics.

Avoid contact with

flow path.

•

Small amounts of graphite can enter capillary

tubing during installation. Remove the first 2-3cm

of tubing after insertion to ensure that no particles

remain in the flow path.

•

Due to the hardness of graphitized vespel the

ferrule should be closely matched to the tubing

OD to obtain a good seal.

0.05mm ID x 0.4mm OD

0.10mm ID x 0.4mm OD

0.18mm ID x 0.4mm OD

0.25mm ID x 0.4mm OD

0.32mm ID x 0.5mm OD

0.53mm ID x 0.8mm OD

SilTite™

Metal Ferrules

SilTite metal ferrules have ben developed specifically for use with GC/MC systems and have distinct advantages

over graphite and composite ferrules for use with GC/MS interfaces:

•

SilTite ferrules form a strong permanent airtight seal around the capillary column

•

The metal SilTite ferrule and nut are made from the same material and therefore have the same thermal

expansion coefficient. As the oven heats up and cools down, the nut and ferrules expand and contract

at the same rate, eliminating annoying leaks and the need to retighten the ferrule after instillation.

•

The base of the SilTite ferrule is flat and forms a perfect seal with the MS interface, covering the

whole transfer interface.

•

Specifically designed non-Swagelok SilTite nuts are characterized by two notches on the outer surface of the nut. The inner taper of

the nut corresponds to the angle of the SilTite ferrule, ensuring an even closure of the ferrule around the whole column eliminating leaks.

•

SilTite nuts are reusable, Unlike graphite Vespel®

ferrules that are nearly impossible to remove from the nuts after use, Siltite ferrules

are easily removed from the specially designed nut while still attached to the capillary column.

•

SilTite metal ferrules have a temperature tolerance well above the limit of the injector, MS interface or GC oven.

•

SilTite nuts and ferrules are available for most major GC/MS instrument interfaces.

•

Removes contamination caused by Vespel or graphite ferrules.

•

Reduced air background gives a cleaner spectra with better library matches.

15% Graphite / 85% Vespel®

Ferrules

•

Mechanically robust

•

Hard material, long lifetime.

•

Temperature Limit 350º C

•

Must retighten after initial temperature cycles

•

Forms strong grip with column

•

For GC-MS interface

Graphite/Vespel

Ferrules

SilTite

Ferrules