Ferrules

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Valco metal ferrules cut a ring near the end of the tube, preventing tube release at high pressures without significantly deforming and restricting the tube interior. (However, if the hardness of the tubing is equal to or greater than that of the ferrule, deformation of the tube rather than a cut ring is likely.) Make up usually takes only about a 1/4 turn beyond the point where the ferrule first starts to grab the tubing.

Valco zero volume ferrules may be used with all Valco fittings and with those of most other manufacturers. The maximum pressure limit is generally determined by the yield strength of the tubing. The exception is for very narrow bore Type 316 stainless steel tubing, where the maximum operational limit of Valco ferrules and fittings is 10,000 psi, regardless of the tubing strength. The maximum pressure for softer materials (such as brass and polymers) is lower, and depends on the tubing used. If in doubt about a particular combination, consult our technical staff.

For trace gas analysis, use gold-plated ferrules to achieve sealing with <10^-9 cc/atm/sec leakage.

Polymeric ferrules seal by the increased friction from compression. Make up usually takes only about a 1/4 turn beyond the point where the ferrule first starts to grab the tubing.

Drawing

Further reference

METAL FERRULES

Stainless ferrules, Type 303

Type 303 stainless is recommended for GC use and general purpose connections. It has good resistance to corrosion and high temperature oxidation, but is susceptible to attack by chlorides, iodides, and bromides.

Sizes available: 1/32”, 1/16”, 1/8”
Sold in packages of 10.

Stainless ferrules, Type 316

Type 316 stainless is most commonly used for HPLC, because of its superior resistance to chloride ions.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”
Sold in packages of 10.

Stainless ferrules, Gold-plated

Gold-plated ferrules, with improved inertness and capability of sealing with <10^-9 cc/atm/sec leakage, are recommended for ultra pure gas analysis.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”
Sold in packages of 10.

Hastelloy C ferrules

Hastelloy C is most often recommended for corrosion resistance, working when nothing else will. Read more.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”
Sold individually.

Nickel ferrules

Nickel 200 has excellent resistance to caustics, high temperature halogens and hydrogen halides, and salts other than oxidizing halides. Resistance is good to caustic soda and other alkalis except ammonium hydroxide.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”
Sold individually.

Titanium ferrules

Although the Grade 2 pure titanium we use is more difficult to machine than the more common alloys, it eliminates any possible contamination of the sample stream with the aluminum and vanadium that alloys contain. Read more about properties of titanium.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”
Sold individually.

Brass ferrules

Brass ferrules are used where a soft metal ferrule is desirable but no corrosive materials are present. Although Valco brass ferrules work as replacements in inexpensive commercial brass fittings, they are generally not recommended for chromatography applications.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”
Sold in packages of 10.

POLYMERIC FERRULES

PTFE, Virgin, ferrules

Polytetrafluoroethylene is the generic name for the class of materials such as Teflon^®. It offers superior chemical resistance but is limited in pressure and temperature capabilities. Because it’s so easy to handle, it is often used in low pressure situations where stainless steel might cause adsorption.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 10.

PTFE, Glass-filled, ferrules

This form of PTFE is nearly as inert as the virgin but is much more mechanically stable.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 10.

FEP ferrules

Fluorinated ethylene propylene is generally more rigid than PTFE, with somewhat increased tensile strength. Because of its slightly higher coefficient of friction, FEP is easier to retain in a compression fitting than PTFE. Read more.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 10.

PEEK ferrules

For higher pressures, see grooved PEEK ferrules for 1/32" and 1/16" tubing.

PEEK can be used instead of stainless in many situations, and in some environments where stainless would be too reactive. However, PEEK can be somewhat absorptive of some solvents and analytes. Read more.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 10.

PFA ferrules

Perfluoroalkoxy is a fluorcarbon with chemical and mechanical properties similar to those of FEP, but with greater rigidity.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 10.

CTFE ferrules

Chlorotrifluoroethylene is very resistant to all chemicals except THF and some halogenated solvents, and resistant to all inorganic corrosive liquids. Read more.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 10.

Polyimide, Graphite, ferrules

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 5.

Polyimide, Valcon, ferrules

Valcon polyimide is specially prepared by a process known as Hot Isostatic Presing (HIP) prior to being machined into individual ferrules. This two step process yields a ferrule with high temperature stability far exceeding that of parts produced by molding. However, it cannot be used with steam or with bases such as strong alkali and aqueous ammonia solutions.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 5.

Polyimide, Virgin, ferrules

Use virgin polyimide Valco ferrules and fused silica adapters as electrical insulators for capillary electrophoresis. Not recommended for general use due to its tendency to be sticky and brittle at high temperatures. Often used as a high temperature electrical insulator.

Sizes available: 1/32”, 1/16”, 1/8”, 1/4”, 3/8”, and 1/2”.
Sold in packages of 5.