Cleaning and Sterilising Systems - CIP, SIP and Autoclave

CIP & SIP - The primary consideration is whether the cleaning and purging cycle is likely to generate an electrostatic charge on the internal surface of the liner, in which case AS is required.

AS hose and static generating systems are described on page 10 of the brochure.

CIP systems using high electrical resistivity solvents like Toluene will require AS hose.

Another problem arises when the cleaning fluids or WFI or steam are purged out of the hose using nitrogen, compressed air or another gas, because droplets of liquids 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 hose.

In applications where an AS hose is not acceptable (in spite of the full approvals ratings, see page 27 of the brochure), it will be necessary to consult with Aflex Hose for a solution.

Autoclave - autoclave sterilisation does not normally involve any high flow rates through the hose bore, so static is not a problem. Grades GP and AS with SS or HB braids can be autoclaved an indefinite number of times throughout their normal service life.

The rubber covered grades RC and SI are also able to withstand many autoclave cycles at normal autoclave temperatures (121°C, 250°F), although eventually the rubber may discolour and / or degrade. Consult Aflex Hose for more specific information.

PTFE Hose - Use with Halogens

PTFE hose liners can react chemically with Fluorine, Chlorine Trifluoride and Molten Sodium Metal, and so must not be used with these chemicals.

When PTFE lined hose is used with the halogens Chlorine and Bromine, or any corrosive halogen compounds which diffuse easily and are gaseous for example HF or HCL gas, or phosgene, then trace quantities may diffuse through the PTFE liner to the outside.

Only trace quantities are required, mixed with atmospheric moisture, to create a serious corrosion condition with stainless steel wire braid in particular.

If these conditions apply, consult Aflex Hose for a more suitable alternative hose product.

'Penetrating' Fluids and Gases

Like other plastics and rubbers, in certain special circumstances PTFE is sometimes subject to diffusion through the tube wall, dependant upon the nature of the chemical, and the pressure and temperature of operation.

As mentioned above, Halogens represent a specific problem. Automotive fuels, on the other hand, diffuse much less through PTFE than through other plastics, like nylon.

Some other types of penetrating fluids can also diffuse through PTFE to varying degrees, which may or may not present a problem. Known examples are sulphur trioxide, glacial acetic acid and methyl methacrylate.

Consult with Aflex Hose if these, or any other gases or fluids which are known to be penetrating are to be used.

Gas/Fluid Cycling

There are some applications where the fluid passing through the hose turns into a gas, then back into a fluid, then into a gas etc., 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 hose is no exception.

Consult Aflex Hose for further information if these conditions apply.

Connecting Assemblies for use in Applications

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 must not be over-tightened as this can damage the sealing surfaces, especially with PTFE lined and flared end fittings.

In applications involving the transfer through the hose of expensive or dangerous fluids or gases, the connections must be pressure tested first before being put in to service. This should be done with some harmless media, like water or compressed air, to 1 1/2 times the maximum working pressure of the hose assembly, as defined in this brochure.

If in doubt, consult Aflex Hose for advice.

Special Applications

Aflex Hose PTFE lined hose products are prohibited from use in the following, special applications:
- Radioactive Applications involving high energy radiation, including Gamma radiation (degrades PTFE).
- Medical Implantation Applications (Not tested for use).
- Aerospace Applications (exclusive contract applies).
- Applications on all types of USA Military Equipment, including tanks, vehicles, weapons, FCS equipment and all others (exclusive contract applies).