Application

PTFE Lined Hose
This flexible hose stainless braided lined with TFE, is used where an extremely smooth, corrosion resistant interior is required.  TFE lined hose consists of a TFE core tube, 304 stainless steel braid, and 316 stainless steel end connections. TFE is inert to almost all commercial chemicals, acids, alcohols, solvents, and many other system fluids. It works well in temperatures from cryogenics up to 450°F (230°C). It is not affected by continuous flexing, vibration, or impulse, and it withstands temperature cycling. It does not absorb either hot or cold moisture and, therefore, can be use in steam applications to 250 psig (17.2 bar). TFE hose maintain a 0.040 maximum wall thickness to help resist permeation, kinking, and abrasion. The smooth core tube is also available in carbon fill TFE if the possibility of static electric discharge exists. 
Common applications: Injection molding, adhesives dispensing, paint spay, hot gas sampling, valve actuation, “clean” air lines, compressor discharge, specialty and standard gas fill applications, paint systems.

Hose and pipe installation

Tubing must be properly support and securely clamp, to avoid vibration and movement, threading swarf and cutting burrs must be carefully removed to stop them from breaking loose and being flushed into the hydraulic system.
Although hoses are cover with a tough outer layer to reinforce and protect the inner layers, this outer layer should not be abraded or damage. Hose must bend in the same plane as the connection to which it is attach, to prevent twisting. The house appearance does not show whether the recommend minimum bend radius has been exceed; the hose reinforcement determines this radius. It is best to check the manufacturer’s specifications prior to installation.

End Connection

End fittings are manufactured to suit the standard thread forms and flanges used throughout the world. 
They are further classified as:
 re-usable (subject to serviceability); and
 permanently attached, which is further divide into
 crimp type, where a tubular sheet steel ferrule fixe to the insert is deformed to crimp the hose between the ferrule and the insert; and
 pallet-swage type, where a separate, machine ferrule is swage onto the hose end to grip the hose between the ferrule and the insert.

Provide that the fittings are correctly attach, it is generally accepted and proven by test results that re-usable as well as permanently attach hose end fittings will outlast the service life of the hose. 

End Connection Sleeve and O-ring

Flare fittings are still widely used, but have lost some ground to compression fittings and O-ring seal fittings. in flare fittings leak tightness is achieve by squeezing the flare end of the pipe against a sealing cone as the compression ring or nut is tighten.
Compression (sleeve) fittings seal by wedging the sleeve onto the pipe and forcing it partly into the pipe surface, so that a slight deformation occurs (fig.). Squareness of the pipe end is not as critical as with flare fittings, and absolute tightness can be guaranteed if tightening procedures and specifications are adhered to.
O-ring seal fittings hold the tube by means of a sleeve wedge onto the tube by the nut (fig). The O-ring provides an absolute seal against leakage. Special O-rings must be used for non-flammable synthetic hydraulic fluids.

Hose selection and rating

Since peak or surge pressure spikes often reach 200 per cent or more of the calculated and adjusted maxi-mum system pressure, hoses and pipes should be select to withstand such pressure peaks. Three pressure ratings are usually given by the manufacturer:  The recommend maximum system pressure (working pressure) at which the hose can be operated continually.
 The test pressure at which a hose is guaranteed to withstand pressure peaks.
 The burst pressure at which the house wall rupture.
The S.A. E. recommended working pressure for hydraulic hose is 25 per cent (or one quarter) of the mini-mum specified burst pressure. This safety margin allows for the absorption of pressure surges. For internal diameter calculations, use the nomogram (fig.) or the formula given for pipe sizing.