(e) Then, tighten the nut an additional one turn past the ring grip point. (f) Unscrew  nut  and  remove  the  tubing  from the mating fitting, or presetting tool.  Inspect the preset as described in Figure 6-1. (g) When  installing  a  preset  tubing  assembly, lubricate  the  threads  and  seat  of  the  fitting and the shoulder of the sleeve with a small amount   of   good   grade   lubricant   such   as clean compressor oil. At  installation  of  tubing  assemblies,  do  not  overtighten tubing nuts. (h) Insert    tubing    assembly    into    fitting    and tighten nut until a sharp rise in torque is felt. Starting   at   position   of   sharp   torque   rise, tighten    the    nut    1/4    additional    turn    to complete the assembly. NOTE At  the  point  where  the  torque  starts  to  rise,  the  sleeve and tubing are just touching the seat.  An additional 1/4 turn produces a seal with the fitting and restores the bow to the sleeve. (3)   Replace damaged or defective fittings. 6-4. DISASSEMBLY   OF   MAJOR   COMPONENTS. Limit  disassembly  of  major  components  to   the   extent necessary  to  repair  or  replace  a  given  assembly.    All major components are covered in the following paragraphs.    Refer  to  Figure  8-1  for  major  components and their attaching hardware. NOTE Unless otherwise specified, all figures referenced in this section will be  found  in  Section  VIII,  Illustrated Parts Breakdown. NOTE Remove  tubing  and  hose  assembly as  needed  (see  Figure  6-1)  in  the disassembly process.  Tag tube and hose assembly for reassembly purposes. NOTE Remove   tubing   clips   as   needed,   tag clips for aid in the reassembly process. 6-5. AIR    PURIFICATION/DEHYDRATOR    GROUP. To remove the air purification/dehydrator group from the air   compressor   unit,   see   Figure   8-1   and   proceed   as follows: NOTE Identify    all    disconnected    or    removed tube assemblies for reassembly purposes. NOTE Remove    tubing    clips    as    needed    for disassembly purposes. a. Disassembly.    Air  purification/dehydrator  group, see Figure 8-2 and proceed as follows: (1) Disconnect   the   rupture   disc   to   tee   tube assembly  (1)  at  tee  (13).    Disconnect  4th stage     cooler     to     mechanical     filter     tube assembly (2) at elbow (16), and mechanical filter  to   drain   valve   tube   assembly   (3)   at elbow (17). (2) Disconnect ten-micron filter to service valve tube assembly (9) at elbow (26). (3) Disconnect   and   remove   tube   assemblies (4, 5, 6, and 8). NOTE Prior  to  removal,  number  cylinders  (19,  22,  23, 24 and 25) as shown (Figure 8-2) for reassembly purposes. Do   not   interchange   or   mix   filter   cartridges   in cylinder (19, 22,  23,  24  and  25).    Contaminated air would result from the mixing of cartridges. (4) Remove nuts (10), screws (12) and washers   (11)   from   mounting   brackets   of mechanical filter (18) and cylinders (19, 22, 23, 24 and 25). (5) Remove  tee  (13),  check  valve  (14),  nipple (15) and elbows (16, 17) from the mechanical filter (18). 6-4