Braids, Covers and End Protection for PTFE hoses

Purpose

TO grade hose (available in both GP and AS) is a lightweight hose, used in applications where working pressures are low and there is no need for the physical protection offered by an external braid. TO grade tube is vacuum resistant to -0.9 bar up to 100˚C.

Note: TO not available in sizes 21/2" & 3" .

Purpose

Stainless Steel braided hose is the general-purpose product and can be used in applications involving high temperatures and working pressures. High tensile AISI 316 stainless steel wire is used, to give maximum pressure resistance and external protection to the hose.

Design

A layer of rubber is applied and vulcanised directly to the ferrule, and 300mm (12 inch) along the hose from the fitting. This can be done either on an SS braided hose (RC-300) or on a rubber covered hose to form a 300mm (12 inch) long double layer of rubber at the end (DRC-300).

The rubber used is normally Blue EPDM, but if the hose is BK, or SI covered, then the same type and colour of rubber would be used (DBK-300 or DSI-300).

Cannot be applied to PB braided hose. If required for a PB hose, consult Aflex Hose for an alternative “EPR” system. EPR includes a 300mm (12 inch) length of loose rubber hose jubilee clipped to the ferrule.

Purpose

In applications where excessive flexing of the hose at the end fitting occurs, it is sometimes necessary to ‘stiffen’ the hose in this area to prevent kinking.

Purpose

Polypropylene braided hose is often preferred to SS in applications involving frequent handling and movement of the hose, and where temperatures are within the range -30˚C and +100˚C (-22˚F to +212˚F). PB braid is lighter in weight, and any broken strands will not cut the operator’s hands. In addition, PB braid is not prone to “chloride stress corrosion” and has generally good chemical resistance.

To ensure Electrical Continuity (EC) between end fittings two strands of Monel wire earthing strips are criss-crossed on to the liner, underneath the Polypropylene Braid. These are folded back underneath the ferrule at both end fittings, to make an electrical contact.

Note: Prolonged exposure to sunlight eventually results in UV degradation of PB braid.

Purpose

As for RC hose, but where the hose may be required to withstand temperatures from -73˚C, -100˚F up to +204˚C, +400˚F, SI grade hose is semi-transparent, allowing visual monitoring of the braid.

Design

An SS braided hose assembly has a platinum cured silicone rubber cover extruded directly onto the braid, with a very smooth external surface finish to aid cleaning.

Specifications

The Silicone rubber cover has been tested and conforms to the requirements of USP Class VI.

 

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Purpose

For many applications, it is required that Smoothbore PTFE hose of all sizes, grades and braids should have an outer cover of a flexible plastic, or rubber.

This is usually required to protect the braid, or to colour the hose, or to allow printing on to the hose.

Plastic covers - available to special order

Flexible PVC covers are the most popular, either transparent, or a wide range of solid or semi-transparent colours.

A particular application is for -3 size single braid, clear PVC covered hose, used as a brake hose for motorbikes, motorsport and special vehicles.

PVC covers are designated as “PVC” followed by the colour if a solid colour is required or “Trans” then the colour if a semi-transparent colour is required. PVC cover will be 0.025” (0.63mm) as standard, alternative cover thickness is available on request.

For example: “-3 HW, SB, PVC Blue” would call for a -3 heavy wall, single braid hose with a solid, blue PVC cover.

Nylon II (Nyl), Hytrel (Hyt), Sarlink (Sar) and other types of flexible thermoplastics are also widely used.

Text can be continuously printed along the hose length, usually in black.

“Pricking” of hose covers

When covered hose is used in gas applications, it is always necessary to “prick” the cover at intervals, to allow the release of any diffused gas. Rubber covered hose is always pricked, but plastic covered hose is not, so pricking must be specially requested for all gas applications requiring plastic covered hose.

Rubber covers - available to special order

Aflex Hose also have rubber extrusion facilities and can continuously extrude rubber covers on to all grades of hose.

EPDM rubber in blue (RC Blue) or black (antistatic) (RC Black), or platinum cured Silicone rubber in transparent (SI) or white (SI White) are available to special order. Other colours and types of rubber may also be available. Consult Aflex Hose for details. Standard thickness of EPDM/Silicone covers are 0.040” (1mm). Other thicknesses are available on request. EPDM covers are only available in sizes from 1/4” (-5).

Colour references

If a particular grade of one colour is required, a RAL Number or a colour reference sample is required.

Note: Coloured covers are to special order, and require a Set-Up Charge, so small quantities are usually not economic.

Special Note: The application of a plastic or rubber cover limits the usage conditions of the hose, particularly the operating temperature ranges, as given below.

Flexible PVC from -10˚C (+14˚F) to +60˚C (+140˚F)

Nylon II from -40˚C (-40˚F) to +120˚C (+248˚F)

EPDM Rubber from -40˚C (-40˚F) to +140˚C (+284˚F)

Silicone Rubber from -73˚C (-100˚F) to +204˚C (+400˚F)

Purpose

Kynar Braid is used in the same application as Hastelloy Braid, but only in applications where the reduced pressure ratings of KYB as listed are acceptable. A Safegard Sleeve is always recommended. Monel or Hastelloy wire should be used.

Full details about the applications should be given to Aflex Hose for evaluation and recommendations.

Purpose

Hastelloy Wire Braid is used instead of SS where severe chemical corrosion conditions exist around the outside of the hose. The most usual way in which this can happen is when Chlorine, Bromine, Hydrogen Fluoride, Hydrogen Chloride or Phosgene are being transferred. Diffusion of trace quantities of such fluids or gases through the PTFE liner can lead to atmospherically wetted halogen chemicals attacking the braid material, in which case the Hastelloy Braid would be resistant up to 60˚C (140˚F) maximum. This should only be used, however, in conjunction with a Monel or Hastelloy Helix Wire.

Full details about the applications should be given to Aflex Hose for evaluation and recommendations.

Specifications

Same as for SS in Specifications & Properties, except the Burst Pressures and the Maximum Working Pressures are both reduced to 80% of the SS pressures listed.

Also, the sizes range is restricted, from 1/2”up to 2” bore only.

Special note:

EC - Electrical Continuity (Also known as “Electrically Bonded”)

The requirements for this are specified in the German Document BRG 132 and EN 16643, when tested in accordance with EN ISO 8031, which requires that the resistance between end fittings shall be <102 ohms per assembly. For hose assemblies which meet this requirement a Grade “M” marking can be applied in accordance with EN 16643.

Design

An SS braided hose assembly has a smooth finish, blue EPDM external rubber cover extruded over and vulcanised directly onto the braid. EPDM has excellent chemical resistance, and the hose has a temperature range from -40˚C, -40˚F up to +150˚C, +302˚F. Alternative colours of rubber, and strips with alternative text titles are available to special order.

Specifications

The Blue EPDM rubber cover has been tested and conforms to the requirements of USP Class VI.

Limitations

Rubber covers are only applicable to SS braided hose.

Purpose

For the most rugged applications where the hose may be subjected to rough treatment and severe external abrasion. Also for hygienic applications, where the external smoothness and cleanability of the hose is of prime importance.

Design

Bioflex Ultra BK grade hose is Fireproof to BS5173 Section 103.13 Part 6.2 and 6.3. When end fittings are assembled to the hose, the assembly is Fire Resistant, but can be made Fireproof by adding DBK-300 rubber cover end protection. Bioflex Ultra BK meets the requirements of EN 16643 flame resistance.

Specifications

The Black EPDM Rubber Cover is anti-static in accordance with specification EN 16643 which specifies a resistance of 103 TO 108 ohms per hose assembly, and meets the requirements for Ώ’ marking if required.

Note: When in service at least one end fitting must be connected to Earth.

Purpose

Bioflex Ultra BK grade is designed to provide an alternative Rubber Cover which has the additional properties of making the hose Fireproof, and also making the rubber cover Anti-static.

Purpose

To protect the hose against external abrasion and mechanical damage. For use in applications where maximum external protection is required with minimum extra hose weight. Particularly useful with PB hose, where a rubber cover is not an option.

Design

A lightweight black, HDPE (High Density Poly Ethylene) strip spirally wound around the outside of the hose over its whole length, secured to each end fitting by crimping under a SS ferrule.

Limitations

Safegard is applicable to all hose grades and all hose sizes from 1/2” up to 2”

Safegard is limited to use within a temperature range from -40˚C (-40˚F) up to +110˚C (230˚F). Internal fluid temperatures up to 140˚C (284˚F) are acceptable, when external temperatures are ambient.

Safegard is applicable to the following hoses; Bioflex Ultra, FaBLine, Corroline+ and Corroflon.

The minimum hose assembly length must be doubled if Safegard is being used. The maximum assembly lengths for all sizes are capped at 20 metres (65 feet).

Other hose usage limitation specifications are not altered by the addition of Safegard.

Safegard is available with anti-static properties and complies with the requirements of a static-dissipative cover within EN 16643. Request details upon enquiry.

 

Purpose

For medium duty applications where the hose requires some protection against abrasion when dragged over the ground, but where a full rubber cover would be too heavy and cumbersome. Also for PB braided hose, which cannot be Rubber Covered.

Limitations

Scuff Rings are applicable to the following hoses; Bioflex Ultra, FaBLine, Corroline+ and Corroflon.

Available for hose sizes 1” (25mm) to 2” (50mm) only. The operating temperature should not exceed 140˚C (284˚F) (internal).

Design

Specially moulded abrasion resistant rubber scuff rings are placed every half metre along the hose.

Purpose

For applications where the hose requires protection against abrasion when dragged over the ground, but where any rubber reinforcement is not permissible due to temperature, chemicals etc.

Limitations

Protection Coils are applicable to the following hoses; Bioflex Ultra, FaBLine, Corroline+ and Corroflon.

Available for all sizes and Grades of Hose including rubber covered grades.

Maximum assembly lengths for all sizes are capped at 30 metres (100 feet).

Design

A stainless steel wire helix is wound onto the braid and welded to the ferrules at each end.

 

Purpose

In applications where the hose assembly may be mechanically abused by pulling the hose with excessive force at an angle to a connected end fitting. Also to render a hose assembly ‘Fireproof’ by protecting the end fitting area against the effects of fire.

Design

A second layer of rubber is applied and vulcanised directly on to the hose and the end fitting ferrule, 12” (300mm) along the hose from the fitting.

Limitations

Double Rubber Cover End Protections are applicable to the following hoses; Bioflex Ultra, FaBLine, Corroline+ and Corroflon.