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Pressure and Vacuum Feedthroughs

General Specifications

Sealed feedthrough assemblies are pressure rated up to 700 bar and can be used in applications at a maximum temperature of +870°C, dependent on the type of feedthrough and sealant material specified.

Sealed feedthroughs for single elements cater for sensors from 0.5mm (0.020”) dia. to 19.05mm (0.75”). Sizes that can be used in multiple element assemblies are from 0.5mm dia. to 6.35mm (0.25”).

Spectite® sealed feedthrough assemblies from TC Ltd. have been designed to be easy to install and can be maintained. Sealants and other internal parts are replaceable so that fittings can be re-used over and over again. If elements need replacement or adjustment, the feedthrough cap can be undone - after the pressure or vacuum in the vessel has been released - to allow movement or removal of all or individual elements.

Process connections
Feedthrough bodies can be specified with a choice of threaded process connections. Feedthroughs with the common tapered threadforms, BSPT (conical gas thread or ‘R’ thread) to BS21, DIN 2999 ISO 7/1 & JIS B0203; and NPT (national pipe tapered thread) to ANSI/ASME B1.20.1 are generally stocked items.

Feedthroughs with parallel threaded process connections, BSPP (parallel gas thread or ‘G’ thread) to BS2779, DIN ISO 228/1 & JIS B0202; and ISO metric to DIN13, may also be specified. Feedthroughs with parallel mounting threads need an ‘O’ ring or a gasket seal (not supplied) to prevent leakage at the process connection.

Feedthroughs without process connection threads may be specified for welded mounting and with a fitted flange from a range of styles including ISO-KF and -CF types for the vacuum industry and general applications as well as Triclover® and triclamp types for the food and pharmaceutical industries.

Custom engineered assemblies can be designed and made to meet customers’ specific application requirements.

Plain, hexagonal caps are available for all sizes of feedthrough. Additionally, caps with a threaded extension for a conduit connection are also available. Specifiers may choose NPT, BSPP (parallel gas thread) or BSPT (conical gas thread). These caps can be specified for feedthroughs with 1/4”, 1/2” & 3/4” process connections. Cap threads are the same size as the corresponding feedthrough body process connection.
Pressure Equipment Directive (PED)
Spectite® sealed feedthroughs have been classified as ‘Piping’, satisfying the requirements of the category of Sound Engineering Practice (SEP), according to the European Pressure Equipment Directive (PED) 97/23/EC. The PED does not require the ‘CE’ symbol to be identified on Pressure Equipment that is categorised as SEP. Caps are marked SPECTITE on one of the hexagon faces.

Feedthrough component materials
Spectite® feedthrough bodies, followers, seats and series EF SS electrodes are manufactured in an austenitic stainless steel UNS S31603, commonly designated 316L. Equivalent grades are: (UK) BS 316 S11; (Germany) W.-Nr. 1.4404, DIN CrNiMo 17.13.2; (France) AFNOR Z2 CND 17.12; (Italy) UNI X2 CrNiMo 17.12; (Sweden) SS2353; (USA) AISI 316L; (Japan) JIS SUS 316L. The typical chemical composition for this steel is 0.03%C, 16.0-18.0%Cr, 10-14%Ni, 2.0-3.0%Mo, 0.10%N. Caps are manufactured in stainless steel UNS S30300 (303).

When 316L is unsuitable for an application, the ‘wetted’ metal parts of feedthroughs, that come into contact with a process, can be manufactured in other stainless grades or other materials such as Hastelloy® and Inconel® grades, Monel® R-405 or mild (carbon) steel. There may be minimum manufacturing requirements for feedthroughs in ‘exotic’ materials.

Insulators in series WF feedthroughs with 1/8” process connections and in series EF feedthroughs are manufactured in high-purity recrystallised Alumina (Aluminium Oxide Al2O3).

External, single-bore insulators in series WF feedthroughs are manufactured in aluminous porcelain. Internal insulators are manufactured in a high-performance, engineering plastic for use at temperatures up to +230°C or machineable glass ceramic for use up to +870°C.

Electrical conductors for Series EF feedthroughs are made in grade C101 copper or 316L stainless steel (as above). Nuts and washers on copper conductors are brass, stainless steel conductors have stainless steel nuts and washers.

The lubricant used on feedthrough components is Chlorotrifluoroethylene Polymer (PCTFE). A copy of the Safety Data Sheet is available on request. Spectite® feedthroughs should not be degreased before installation.