PFTE

Fluid Power - Intro to Hydraulics, Pneumatics, and how it all works
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Technical Directive for Piping Devices and Flexible Hose Assemblies, NAVSEA S6430-AE- TED-010. volume 1. provide detailed instructions on discarding and downgrading of rubber hoses exceeding their shelf life. PFTE 1Q89 or the first Figure 5-10.—Hose identification. 1/89 means the hose was made during quarter (1 Jan to 31 Mar) of 1989. The cure date limits the length of time a rubber hose can be stored, in bulk or as an assembly, prior to being placed into service. The storage or shelf life for rubber hose is 4 years. For the hose manufactured in 1Q89, the storage or shelf life will end on the 31st of March 1993. At this point, the hose is no longer considered usable and should be discarded or downgraded. The Aviation Hose and Tube Manual, NAVAIR 01-1A-20, and the 5-9 PFTE hose is a flexible hose designed to meet the requirements of higher operating pressures and temperatures in present fluid power systems. This type of hose is made from a chemical resin, which is processed and extruded into a tube shaped to a desired size. It is reinforced with one or more layers of braided stainless-steel wire or with an even number of spiral wrap layers with an outer wire braid layer. PTFE hose is unaffected by all fluids presently used in fluid power systems. It is inert to acids, both concentrated and diluted. Certain PFTE hose may be used in systems where operating temperatures range from –100°F to +500°F. PTFE is nonflammable; however, where the possibility of open flame exists, a special asbestos fire sleeve should be used. PFTE hose will not absorb moisture. This, together with its chemical inertness and anti- adhesive characteristics, makes it ideal for missile fluid power systems where noncontamination and cleanliness are essential. In lieu of layline marking, PTFE hoses are identified by metal or pliable plastic bands at their ends and at intervals along their length. Figure 5-10, view C, shows a hose label for a PTFE hose. Usually the only condition that will shorten the life of PTFE hose is excessive temperature. For this reason there is no manufacture date listed on the identification tag. APPLICATION As mentioned earlier, flexible hose is available in three pressure ranges: low, medium, and high. When replacing hoses, it is important to ensure that the replacement hose is a duplicate of the one removed in length, OD, material, type and contour, and associated markings. In selecting hose, several precautions must be observed. The selected hose must 1. 2. be compatible with the system fluid, have a rated pressure greater than the design pressure of the system,

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