Synthetic Rubber Hose Synthetic rubber hose has a seamless synthetic rubber inner tube covered with layers of cotton and wire  braid,  and  an  outer  layer  of  rubber  impregnated cotton braid. The hose is provided in low-, medium-, and  high-pressure  types. Synthetic  rubber  hose  (if  rubber-covered)  is identified  by  the  indicator  stripe  and  markings  that  are stencilled along the length of the hose. The indicator stripe (also called the lay line because of its use in determining  the  straightness  or  lie  of  a  hose)  is  a series of dots or dashes. The markings (letters and numerals)  contain  the  military  specification,  the  hose size,  the  cure  date,  and  the  manufacturer’s  federal supply code number. This information is repeated at intervals of 9 inches. Refer to figure 5-2. Size is indicated by a dash followed by a number (referred to as a dash number). The dash number does not denote the inside or outside diameter of the hose. It refers to the equivalent outside diameter of rigid tube size in sixteenths (1/16) of an inch. A dash 8 (-8) mates to a number 8 rigid tube, which has an outside diameter  of  one-half  inch  (8/16).  The  inside  of  the hose will not be one-half inch, but slightly smaller to allow  for  tube  thickness. The  cure  date  is  provided  for  age  control.  It  is indicated by the quarter of the year and year. The year is divided into four quarters. 1st  quarter  —  January,  February,  March 2d quarter — April, May, June 3d quarter — July, August, September 4th quarter — October, November, December The   cure   date   is   also   marked   on   bulk   hose containers in accordance with Military Standard 129 (MIL-STD-129). Synthetic rubber hose (if wire-braid covered) is identified by bands wrapped around the hose at the ends and at intervals along the length of the hose. Each  band  is  marked  with  the  same  information (fig.5-2). are  its  operating  temperature  range,  its  chemical inertness  to  all  fluids  normally  used  in  hydraulic  and engine lubrication systems, and its long life. At this time,  only  medium-pressure  and  high-pressure  types are  available.  These  are  complete  assemblies  with factory-installed  end  fittings.  The  fittings  may  be either the detachable type or the swaged type. When failures   occur,   replacement   must   be   made   on   a complete  assembly  basis. Teflon®  hose  is  identified  by  metal  bands  or pliable   plastic   bands   at   the   ends   and   at   3-foot intervals.  These  bands  contain  the  hose  military specification  number,  size  indicated  by  a  dash  (-)  and a number, operating pressure, and the manufacturer’s federal supply code number. Refer to figure 5-2. HOSE ASSEMBLY HARDWARE Hose  fittings  are  designed  and  constructed  in accordance with military specifications and military standard  drawings  for  particular  hose  configurations and  operating  pressures. Fittings   designated   by   a   military   standard drawing number have a particular dash number to indicate  size. The  fitting  dash  number  does  not designate a size in the same manner as a hose dash number. The fitting dash number corresponds to the dash number of the hose so that both will match at the critical  dimensions  to  form  a  hose  assembly. Materials used in the construction of fittings vary according   to   the   application. Materials  include aluminum,  carbon  steel,  and  corrosion-resistant  steel. Fittings that qualify under one military document may be produced by several manufacturers. Two methods or styles are used to secure the hose fitting on to the hose. They are the reusable and swage or crimp style. Reusable Style Teflon® Hose The preferred reusable style has modified internal threads in the socket to grip the hose properly. The The  Teflon®  hose  is  made  up  of  a  tetrafluoro- fitting can be disassembled from a hose assembly and ethylene resin, which is processed and extruded into reused  on  another  hose,  provided  it  passes  an tube  shape  to  a  desired  size.  It  is  covered  with inspection  for  defects. Reusable style fittings are stainless steel wire, which is braided over the tube for authorized  replacement  fittings  for  replacement  hose strength  and  protection.   The  advantages  of  this  hose assemblies. 5-2