GRA-50\( \).

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MIL-PRF-55371B(CR)

source of manufacture may be determined. Each tape shall also be legibly marked on the

outside of the case in a plain and permanent manner with the length of the tape.

3.5.7 Ribbon assembly. The ribbon shall be constructed of synthetic fiber (e.g. unwoven

fiberglass, polyvinyl coated or similar material). All the threads used in the construction of the

ribbon shall be fungus resistant. The ribbon shall be between 1/2 and 7/8 inches wide, and the

woven tapes shall have a selvage (woven edge) located at each edge. The ribbon shall be easily

replaced in the tape, when required.

3.5.7.1 Ribbon strength. The strength of the ribbon shall be sufficient to withstand a 80

pound load applied to each end. This required strength shall be demonstrated via testing in

compliance with 4.5.4.

3.5.7.2 Ribbon abrasion resistance. The ribbon shall be constructed to resist abrasion due

to normal to heavy use in extreme environmental conditions. The normal process of deploying

and reeling up the ribbon with the handle will produce some apparent normal wear over years of

use and shall be considered in the construction of the ribbon and the quality of the graduations

and markings placed on the ribbon. When the ribbon is deployed with any over a portion of its

entire length of 156 feet, the surface of the ribbon may be subject to abnormal abrasion when it

makes contact with the ground. The ribbon portion may suffer most significant abrasion when

its either dragged over the ground during use or while being reeled. The aforementioned

abrasion situations shall be provided for in the design and construction of the ribbon and its

graduations. A documented demonstration of abrasion resistance shall be performed by the

contractor on selected samples of graduated ribbons (in accordance with 4.5.5). The useful life

of the ribbon shall be ten (10) years.

3.5.7.3 Ribbon finger ring. A corrosion resistant ring shall be attached to the outer end of

the ribbon large enough for a finger hold and strong enough to prevent breakage. The ring shall

be fastened to the ribbon in a manner which permanently affixes the ring to the ribbon. The ring

shall be the same width as the ribbon. The finger ring shall withstand the following test: Each

sample Tape ribbon shall be supported at 4-1/2 inches from the tip of the finger ring and a 40

pound test load applied across the finger ring to 75 percent of its width, for not less than five

minutes. The ribbon shall not break or be pulled out of the clip fastened to the finger ring, and

the finger ring shall not break or deform when tested in accordance with 4.5.7.

3.5.7.4 Reinforcement. Reinforcement shall be provided on the outer end of the ribbon

for not less than 4 inches by a strip of leather, plastic or other abrasion resistant material of the

same width as the ribbon. The reinforcement shall be fungus and mildew resistant. The

reinforcement shall pass around the ring and under the clip.

3.5.8 Graduations. One side of the ribbon shall have graduations marked in feet, tenths

and half-tenths of a foot. The graduation lines and tenth of a foot indication numerals shall be in

black, and the foot indication numerals shall be in red. The outside end of the ring shall be the

point of origin or "zero" point.