FED-STD-228A
Method 7121.1
18 APRIL 2014
CONDUCTOR COATING, SODIUM POLYSULFIDE
1. SCOPE
1.1 This method is intended for use in determining the uniformity of the coating on copper conductors of
insulated wire and cable. It is applicable to tin-lead-, and lead-alloy coated copper. For determining the
uniformity of lead or lead-alloy coatings method 7123 gives more conclusive results and should be used
in case of dispute when these two determinations are involved.
2. SPECIMEN
2.1 The specimen should be the conductor removed from a piece of the inspection unit at least 6 inches
in length.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents shall be as follows:
3.1.1 Glass containers of sufficient size to hold 180 ml. of solution and permit immersion of at least 4 ½
inches of specimen.
3.1.2 Hydrochloric acid, sp. gr. 1.088.
3.1.3 Sodium polysulfide, sp. gr. 1.142.
4. PROCEDURE
4.1 Preparation of test solution. The test solutions, 3.1.2 and 3.1.3, shall be prepared as follows:
4.1.1 Sodium polysulfide solution (specific gravity 1.142). A concentrated solution shall be prepared by
dissolving sodium-sulfide crystals in distilled water to form a saturated solution in 15.5°C (60°F), adding
250 grams of flowers of sulfur per liter of solution and allowing the solution to stand for at least 24 hours.
The test solution shall be prepared by diluting the concentrated solution with distilled water to a specific
gravity of 1.142 ± 0.002 at 15.5°C (60°F). This test solution should have sufficient strength to thoroughly
blacken a piece of clean untinned copper wire in 5 seconds. The solution shall be considered to be
exhausted when it fails to blacken a piece of clean copper within 5 seconds.
4.1.2 Hydrochloric acid solution (specific gravity 1.088). This solution shall be prepared by diluting
concentrated hydrochloric acid to a specific gravity of 1.088 ± 0.002 at 15.5°C (60°F) with distilled water.
This solution shall be considered exhausted for test purposes when the following number of specimens
have been immersed in a volume of 180 milliliters of the acid for two cycles:
193
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business