Pressure and Vacuum Sealed Feedthroughs from TC Ltd.
01895 252222 |

Series ASF Pressure and Vacuum Sealed Feedthroughs for Autoclave Sensors

Need advice on choosing
a Feedthrough?

Contact one of our engineers on
01895 252222 or send us an email

These feedthroughs are designed for use within sterilising and composite autoclave applications, sealing multiple sensor or instrumentation wires exiting an enclosure.

Series ASF feedthroughs seal thermocouple pairs insulated in a single shot PTFE cable which is gas, steam and water tight. Available in thermocouple types K, J, T and N.

There are three body sizes (2 to 4) 1/4", 1/2" and 3/4" process connections with BSPT (conical gas or DIN 2999 'R') and NPT threads along with ISO, SAE and UNF threads as shown in the Feedthrough Thread Sizes section.

Spectite® feedthroughs are designed for ease of assembly and installation. Elements can be adjusted, removed and replaced when not under pressure or vacuum conditions.

The thermocouple pairs are available with or without junctions. Please contact us for further details.

  • Seal on PTFE single shot thermocouple wires
  • Immersion length of the element can be easily adjusted
  • Three sizes of feedthrough assembly
  • Guide pressure range: Vacuum up to 3 bar
  • Temperature range: -40°C to +225°C
  • 316L Stainless steel wetted parts (see Cutaway View)
  • Reusable and replaceable internal components
Standard Body Style ('A' Cap) Threaded Extension ('B' Cap) Weld Neck Flanges
Standard body style suitable for most applications. Allows the gland to be terminated into the process as well as to a terminal head or conduit at the opposite end to the process. Supplied without thread for permanent installation into the process by welding.
Specify as 'WELD' for the thread size in the order code.
For termination to a mating flange within the process, see Optional Flanges for details of the flanges available as standard.
Size 2 (1/4" Thread or equivalent) Size 3 (1/2" Thread or equivalent) Size 4 (3/4" Thread or equivalent)
Standard Thread Sizes Standard Thread Sizes Standard Thread Sizes
1/4" BSPT, 1/4" BSPP, 1/4" NPT 1/2" BSPT, 1/2" BSPP, 1/2" NPT 3/4" BSPT, 3/4" BSPP, 3/4" NPT
Alternative Thread Sizes Alternative Thread Sizes Alternative Thread Sizes
M10x1.0, 7/16" UNF-20 3/8" BSPT, 3/8" BSPP, 3/8" NPT M22x1.5, 3/4" SAE-16, 7/8" UNF-14
M12x1.5, 1/2" UNF-20 M14x1.5, 7/16" SAE-20, 9/16" UNF-18 M24x2.0, 7/8" SAE-14, 1" UNF-14
  M16x1.5, 1/2" SAE-20, 5/8" UNF-18  
M20x1.5, 9/16" SAE-24, 3/4" UNF-16
Sealant Material Code Colour Example Operating Temperature Range Re-usable Material definition and properties
Viton® V Brown -40°C to +225°C
(intermittently to +285°C)

Fluoroelastomer. Resists hydrocarbons, corrosive chemicals and petroleum. Solvent, acid and base resistant. Low permeation rate. Mechanically robust at high temperatures.

Style 'A' (Supplied as standard) Description Style 'B' (Alternative cap) Description

Standard Fitting with single thread for direct mounting into process.

Standard Fitting with a Style B threaded extension for conduit/terminal head or enclosure connection. The thread form is the same as the process thread unless otherwise specified.

If a different thread form is required, please specify after the 'B' in the order code, for example:
ASF2 - 1/4" BSPT - K-IEC - 3 - V - B NPT

If a B cap is used with a weld neck fitting, then the thread form must be specified.

Style Example Part Code Maximum Compatible
Body Size
KF FLANGE KF16 Size 2 30mm 5.08mm
KF25 Size 3 40mm 5.08mm
KF40 Size 5 55mm 5.08mm
KF50 Size 5 75mm 5.08mm
CF FLANGE DN16CF Size 3 33.8mm 7.6mm
DN25CF Size 4 54.0mm 11.9mm
DN35-40CF Size 5 69.9mm 12.7mm
DN50CF Size 5 85.7mm 16.0mm
DN63CF Size 5 114.3mm 17.3mm
All flanges are supplied in 304L stainless steel as standard. Hygienic and Food Grade Flanges are also available - please contact us for further details.
CF Flanges are non-rotatable (fixed) type and comply with ISO3669-2017.
KF Flanges are compatible to the ISO Standard 2861 Specification.
Many other styles of flange available on request (DIN, JIS, ANSI, etc.), contact TC Ltd. for details.

Body Size, Pressure Guide and available Bore Sizes for BSPT, BSPP and NPT Threads2

Body Size No. of
Size 2 (1/4") No. of
Size 3 (1/2") No. of
Size 4 (3/4")
Sealant V V V
Wire Size (dia)3 The maximum guide pressure value (in bar) at 20°C is shown for each sealant material according to element size1.
These ratings are a guide and the suitability of any of the products described herein for a particular application
is entirely at the discretion of the purchaser as being the best judge for that particular application.
Conductor Overall
0.376mm 2.3mm 1 to 4 3 bar 1 to 8 3 bar 1 to 24 3 bar
  1. The guide pressures shown for each type of sealant are at 20°C. Spectite® feedthroughs from TC Ltd. have been designed to provide an efficient seal on the elements and restrain them from moving under pressure and vacuum. It is good installation practice to provide additional, mechanical restraint to the elements when differential pressure exceeds 50% of the feedthrough guide pressure value at 20°C. With an increase in temperature, a reduction in the maximum guide pressure value can be expected. These ratings are a guide and the suitability of any of the products described herein for a particular application is entirely at the discretion of the purchaser as being the best judge for that particular application.
  2. Other types of process connection are available, see Feedthrough Sizes.
  3. Each pre-installed element is a single PTFE standard autoclave thermocouple cable - see Cable Details.
    Blank (undrilled) sealants are also available for series ASF feedthroughs. When a blank sealant is required, the word 'Blank' should be inserted in the order code instead of an element diameter.
    Feedthroughs with blank sealants are not pressure rated.
Size 2 (1/4" Thread or equivalent) Size 3 (1/2" Thread or equivalent) Size 4 (3/4" Thread or equivalent)
Please note: the overall length will vary slightly depending on the sealant used and the tube size.
Illustration Description Colour Codes available

Available in thermocouples types K, J, T and N, this cable comprises a pair of solid thermocouple conductors 1/0.376mm diameter (27AWG) encased in a 'single shot' PTFE insulation (round construction, 2.3mm overall diameter).

PTFE 'single shot' cables are gas, steam and water tight making them ideal for autoclave applications.

Supplied according to IEC colour codes as standard, although ANSI colours are available on request.

Enquiry Form - Autoclave Sensor Feedthrough

1. Feedthrough Body Size

2. Thread Size

3. Thermocouple Type

4. Colour Code

5. Number of Thermocouples

6. Cap Style

7. Wire Length CAP SIDE

8. Wire Length PROCESS SIDE

5a. B Cap Thread Size (other)

9. Optional Flange

10. Quantity Required

Additional Information

If you are unsure about the specification of the fitting you require, please use the box below to tell us about your application and one of our experienced engineers will call you back to help guide you through the selection process.

Otherwise, please use the drop down boxes provided and we will arrange for a quotation to be sent to you.

Contact Details

Send Enquiry
We will only use your email address to contact you. We will never give your email address to 3rd parties and we do not sell data on to any other company.