FED-STD-228A
Method 7211.1
18 APRIL 2014
MINERAL CONTENT, COVERINGS
1. SCOPE
1.1 This method is intended for use in determining the mineral content of the fibrous coverings of
insulated wire and cable. It is especially applicable to wire and cable designed to be weather-resistant.
2. SPECIMEN
2.1 The specimen should be the fibrous covering with the adhering compound taken from a piece of the
inspection unit at least 6 inches in length.
3. APPARATUS
3.1 The apparatus shall consist of a 75 ml. crucible.
4. PROCEDURE
4.1 The specimen shall be placed in a tared crucible (W2), weighed, and the weight recorded as W. The
crucible containing the materials shall be heated at low temperature to remove most of the flammable
material and ashed to a constant weight at about 600°C. (1112°F) in a muffle furnace. The crucible shall
be cooled to room temperature in a desiccators, weighed, and the weight recorded as W1. The weights
shall be made to an accuracy of 1 milligram.
4.2 Unless otherwise specified in the detail specification, in constructions involving two or more over-all
fibrous coverings, the mineral filler content of all the fibrous coverings shall be determined in one
operation as described in 4.1 for the outer covering.
5. RESULTS
5.1 Calculation. The mineral content of the specimen shall be calculated as follows:
Mineral content of fibrous covering percent=W1-W2 x 100
W-W2
where:
W1=the weight of the ash plus crucible
W=the weight of the covering materials plus crucible
W2=the weight of the crucible
5.2 Unless otherwise specified in the detail specification, one specimen from each inspection unit shall
be tested.
5.3 The mineral content of the covering of the inspection unit shall be the result obtained on the
specimen tested.
5.3.1 When more than one specimen is tested, the mineral content of the covering of the inspection unit
shall be the average of the results obtained from the specimens tested.
5.4 The mineral content of the fibrous covering of the inspection unit shall be recorded to the nearest 1
percent.
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