5.2.3.3
Tumbling The drum rotation rate shall be 5.0 rpm Âą 1.0 rpm.
The drum shall be rotated through 72,000 Âą 1,500 complete rotations during the test. To ensure that the proper number of complete rotations is obtained, a counter or totalizer shall be used to record the total number of rotations. The drum rotation rate may be varied within the given tolerance to achieve the necessary number of rotations, as long as the rate does not exceed the above specified tolerance. 5.2.3.4
Test duration The test shall last a total of 10 d Âą 1 h.
5.3
Laboratory Configuration and Test Equipment
5.3.1 5.3.1.1
General Parameters Facility Design
Use a stand-alone or walk-in temperature and humidity chamber with the tumbling accessory inside. 5.3.1.2
Monitoring Conditioning Chamber Parameters
To provide proof of parameter level maintenance, the laboratory must keep a manually or electronically produced log of parameter levels. Exact parameter monitoring intervals and exact methods of recording parameter levels may vary for different laboratories. The technology involved in recording parameter levels may involve visual checks at prescribed intervals, real time continuous recording such as a circular chart, periodic recording on a device such as a data logger, or other techniques as appropriate for each individual laboratory. 5.3.1.3
Humidity Generation
Use steam or water injection to create the relative humidity within the test chamber as appropriate for the device. Set up a system to drain and discard any condensate developed within the chamber during the test. 5.3.1.3.1 Water Purity It is essential that the water used for humidity tests not unfairly impose contaminants on the test samples. Chemicals commonly found in commercial water supplies, such as chlorine, as well as nonneutral pH, can cause unintended corrosive effects to materials. It is highly recommended that the water used for this test be relatively free from impurities and chemicals and have a pH in the range of 6.5 to 7.2. NOTE: A water resistivity of no less than 150,000 ohm cm is recommended. This can be produced using distillation, demineralization, reverse osmosis, or deionization. Many humidity chambers have a built in deionization system.
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