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.
PVC - 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.
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).
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.
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
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)