Flexible Hose

a clamp to lock the end of the tubing inside the die block, and a yoke with a compressor screw and cone that slips over the die block and forms the 45-degree flare on the end of the tube. The screw has a T-handle. A double flaring tube has adaptors that turn in the edge of the tube before a regular 45-degree double flare is made. To use the single flaring tool, first check to see that the end of the tubing has been cut off squarely and has had the burrs removed from both inside and outside. Slip the flare nut onto the tube before you make the flare. Then, open the die block. Insert the end of the tubing into the hole corresponding to the OD of the tubing so that the end protrudes slightly above the top face of the die blocks. The amount by which the tubing extends above the blocks determines the finished diameter of the flare. The flare must be large enough to seat properly against the fitting, but small enough that the threads of the flare nut will slide over it. Close the die block and secure the tool with the wing nut. Use the handle of the yoke to tighten the wing nut. Then place the yoke over the end of the tubing and tighten the handle to force the cone into the end of the tubing. The completed flare should be slightly visible above the face of the die blocks. FLEXIBLE HOSE Shock-resistant, flexible hose assemblies are required to absorb the movements of mounted equipment under both normal operating condi- tions and extreme conditions. They are also used for their noise-attenuating properties and to connect moving parts of certain equipment. The two basic hose types are synthetic rubber and polytetrafluoroethylene (PTFE), such as Du Pont’s Teflon^®fluorocarbon resin. Figure 5-9.—Synthetic rubber hoses. pressure ranges: low, medium, and high. The outer cover is designed to withstand external abuse and contains identification markings. Synthetic rubber hoses with rubber covers are identified with the military specification number, the size by dash number, the quarter and year of cure or manufacture, and the manufacturer’s code identification number or federal supply code number printed along their layline (fig. 5-10, view A). The layline is a legible marking parallel to the longitudinal axis of a hose used in determining the straightness or lay of the hose. Synthetic rubber hoses with wire braid cover are identified by bands (fig. 5-10, view B) wrapped around the hose ends and at intervals along the length of the hose. Sizing Rubber hoses are designed for specific fluid, temperature, and pressure ranges and are provided in various specifications. Rubber hoses (fig. 5-9) consist of a minimum three layers; a seamless synthetic rubber tube reinforced with one or more layers of braided or spiraled cotton, wire, or synthetic fiber; and an outer cover. The inner tube is designed to withstand the attack of the fluid that passes through it. The braided or spiraled layers determine the strength of the hose. The greater the number of these layers, the greater is the pressure rating. Hoses are provided in three 5-8 The size of a flexible hose is identified by the dash (-) number, which is the ID of the hose expressed in 16ths of an inch. For example, the ID of a -64 hose is 4 inches. For a few hose styles this is the nominal and not the true ID. Cure Date Synthetic rubber hoses will deteriorate from aging. A cure date is used to ensure that they do not deteriorate beyond material and performance specifications. The cure date is the quarter and year the hose was manufactured. For example,