CIP & SIP – PTFE liner tubes are chemically resistant to all CIP, SIP and Autoclave conditions. A primary consideration is whether the cleaning and purging cycle is likely to develop an electrostatic charge on the internal surface of the liner, in which case AS (Anti-Static) grade hose is required.
AS grade hose and Electrostatic charge generating systems are fully described in the hose liner section.
CIP systems using high electrical resistivity solvents like Toluene will require AS grade hose.
Another electrostatic generation problem arises when wet steam is passed through, or when the cleaning fluids or WFI are purged out of the line using nitrogen, compressed air or another gas, because droplets of liquid or water in the gas then generate a multi-phase condition until they are cleared out, which will generate a static charge, and so will require AS grade hose.
Pharmaline N hose is able to withstand at least 300 x 30 minute autoclave cycles at relatively high autoclave temperatures (up to 135°C, 275°F). Please note that in robust applications the Silicone cover may become more susceptible to tearing after extended autoclave cycles. Consult Aflex Hose for more specific information.
PTFE hose liners react chemically with Fluorine, Chlorine Trifluoride and molten Alkali Metals and so no hose grades are suitable for use with these chemicals.
When PTFE lined hose is used to carry Chlorine or Bromine, either as gasses or fluids, trace quantities can diffuse into and through the PTFE liner wall thickness. These will then combine with atmospheric moisture to corrode the SS braid or rubber cover outside the liner tube. It has been found that Corroflon SP, HB or KYB hose is best suited for these applications - Please consult the Corroflon brochure.
Depending upon the internal pressures and temperatures, some other gasses and fluids with a high halogen content may also be transmitted in trace quantities through the wall of the PTFE tube, including Hydrogen Fluoride, Hydrogen Chloride, Carbonyl Chloride (Phosgene), Carbon Tetrachloride and others. Please consult with Aflex Hose for a suitable hose grade recommendation.
Sulphur Trioxide, Methyl Methacrylate, Caprolactam and Glacial Acetic Acid are some other chemicals which do not react chemically with the PTFE, but which can be absorbed and transmitted in trace quantities through the PTFE liner tube wall - please consult Aflex Hose for the optimum solution with these chemicals.
Generally, however, as a hydrophobic (non-wetting) material, PTFE is very resistant to the absorption of chemicals. In some cases, PTFE has superior resistance to diffusion, for example to the diffusion of automotive fuels, in comparison with all other plastics and rubbers.
There are some applications where fluids then gasses are passed through the hose, in a cyclic sequence.
This is normally associated with changes in temperature and/or pressure. For complex reasons these conditions are extremely damaging to the hose liner, whatever material it is made from.
For example, hoses are sometimes used to pass steam, water, steam etc into rubber moulding presses, in order to heat the mould, then rapidly cool it before reheating in the next cycle. Hoses of all types fail rapidly in such an application and PTFE lined hoses are no exception.
Please contact Aflex Hose for further information if these conditions apply.
The lengths of hose assemblies and their configuration in use when connected into the application must always be in accordance with the Hose Configuration information at the end of this product literature.
When being connected for use in applications, the end fittings on hose assemblies must be connected to correct mating parts in the correct way, using the correct tools, spanners, clamps, nuts and bolts etc. The connections must be sufficiently tightened to ensure that the joint is leak free but not be over tightened as this can damage the sealing surfaces.
In applications involving the transfer through the hose of expensive or dangerous fluids or gases, the hoses and connections must be pressure tested in situ before being put in to service. This should be done with some harmless media to 2.0 times the maximum working pressure of the hose assembly, as stated in the product literature.
If in doubt please contact Aflex Hose for advice.
Aflex Hose PTFE lined hose products are not rated as suitable for use in the following, special applications: