FED-STD-228A
Method 4111.1
18 APRIL 2014
RESISTANCE OF OZONE, INSULATION AND SHEATH
1. SCOPE
1.1 This method is intended for use in determining the resistance of rubber and rubber-like insulation and
sheaths to ozone attack which may be encountered in connection with the operation of high-voltage
cable.
2. SPECIMEN
2.1 Each specimen should consist of a piece of the insulation or sheath from the inspection unit taken at
least 5 feet from the end of the coil or reel of wire or cable. The length of the specimen necessary for test
will depend on the diameter of the wire or cable. The specimen should not include any tapes or outer
coverings except when a tape or sheath has been applied directly over the insulation prior to and left in
place during vulcanization.
2.2 When the over-all diameter of the wire or cable is less than 1 inch, the specimen should be bent at
room temperature through an angle of 360° around a mandrel, without twisting. The diameter of a
mandrel should be 4 ± 0.5 times the outside diameter of the wire or cable. The two ends of the piece
should be tightly clamped to the mandrel to prevent any movement of the bent section during the test.
2.3 When the over-all diameter of the wire or cable is 1 inch and greater, the specimen should be bent at
room temperature through an angle of not less than 180° around a mandrel without twisting. The
diameter of the mandrel should be 6 ± 0.5 times the outer diameter of the wire or cable.
2.4 In the case of flat twin cable, the minor diameter should be used in arriving at the size of the mandrel.
2.5 Two specimens should be prepared from each inspection unit. One specimen should be prepared as
described in either 2.2 or 2.3, as required. The other specimen should be prepared in the same way but
bent in the reverse direction.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents shall be as follows:
3.1.1 A suitable apparatus for ozone resistance test is shown assembled on figure 4111. All connections
for parts of the apparatus carrying ozonized air should be of ozone-resisting materials. The apparatus
consists essentially of the following parts.
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