Object
This test applies to continuously water-blocked cables. The purpose is to determine the ability
of a cable to block water migration along a specified length.
Compliance shall be checked on samples of cable using one of the two following methods (F5A or F5B), as stated in the detail specification. Method F5A tests for water migration between the outer interstices of the optical core and the outer sheath, whereas method F5B tests for water migration over the entire cross-section designed to be water-blocked.
Method F5B
A cable sample 1 m longer than the length to be tested, which shall not exceed 3 m is used. A maximum cable length of 3 m shall then be taken from the central portion of the sample. A watertight seal shall be applied to one end of the sample to allow a 1 m height of water to be applied.
NOTE – For armored cables where the armor is not designed to be water-blocked, the armor may be removed before the application of the seal.
Procedure
Unless otherwise specified in the detail specification, the sample shall be supported
horizontally and a 1 m height of water shall be applied for 24 h, at a temperature of (20 ± 5) °C.
A water-soluble fluorescent dye or other suitable coloring agent may be used to aid in the
detection of water seepage. Care should be taken in choosing a fluorescent dye that does not react with any of the cable components.
Requirements
No water shall be detected at the unsealed end of the sample. If a fluorescent dye is used, an
ultraviolet light may be used for the examination.
NOTE – The test procedure mentioned above is a basic compliance requirement and for routine tests; samples of shorter length may be tested for a shorter time.