MIL-PRF-14442E(AT)
Applicable service procedures shall be followed in tank installation and removal. All fittings shall
be fastened to corresponding structure and interconnect fittings upon each installation in the test
structure, and the tank shall then be examined.
4.8.2 Fluid resistance of exterior surfaces. To determine conformance to 3.5.5, a
6 by 6 in. specimen of composite tank construction shall be submerged in a container of test fluid
conforming to reference fuel B of ASTM D471 at standard ambient temperature for 24 hours.
4.8.3 Permeability. To determine conformance to 3.5.6, the fuel tank shall be tested as
specified in 4.8.3.1 through 4.8.3.3.
4.8.3.1 Test apparatus. The test apparatus shall include a permeability cup and ring
constructed in accordance with figure 1. A nylon solution shall be used for sealing the test disk to
the permeability cup.
4.8.3.2 Preparation of test specimen. The uncured liner shall be applied to a 10 by 10 in.
piece of corrugated fiberboard coated on one side with a suitable water soluble breakaway agent.
The exposed surface of the inner liner shall be coated with prime cement and barrier resin, if
required, in accordance with applicable manufacturing specifications. The assembly shall be
wrapped with cellophane and covered with a waterproof bag. The assembly shall be vulcanized
using the same method as in regular production. After vulcanization, the waterproof bag and
cellophane shall be removed, and the inner liner shall be removed from the fiberboard, using water
if necessary. Free moisture shall be wiped from the assembly, and the assembly shall be
conditioned for 24 hours at a constant temperature of 77 + 50°F and a relative humidity of
40 + 5%. Two disks, each 2.5 in. in size, shall be cut from the vulcanized panel. One hundred ml
of the test fluid conforming to reference fuel B of ASTM D471, shall be placed in the diffusion
cup shown in figure 1. A nylon solution shall be applied to the face of the cup flange covering the
area inside the bolt circle. The nylon solution shall be allowed to come almost to dryness, then
the test disk shall be applied to the cup with the barrier, if any, facing outward. The assembly
shall be completed by attaching the bolting ring and tightening the bolts in accordance with the
following schedule:
Inner liner type
Bolt torque, pound-inches (lb-in)
Gum stock
5 to 10
Coated fabrics
15 to 20
Unsupported plastic films
20 to 25
4.8.3.3 Method of conducting test. Permeability cups, prepared as specified in 4.8.3.2,
shall be placed in a rack in a constant temperature of 77 + 5°F and relative humidity of 40 + 5%.
After allowing one hour for equilibration, the cup shall be weighed to the nearest 0.005 gram (g)
and placed in the rack with the cup facing upward. The cup shall be kept at the above constant
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