1. Objective

The following procedure is used to evaluate the moisture absorption and retention characteristics of a new lot of test cloth by measuring the remaining moisture content (RMC) in a standard extractor at a specified set of conditions. The results are used to develop a set of coefficients that correlate the measured RMC values of the new test cloth lot with a set of standard RMC values established as an historical reference point. These correction coefficients are applied to the RMC measurements performed during testing according to appendix J1 or appendix J2 to 10 CFR part 430 subpart B, ensuring that the final corrected RMC measurement for a clothes washer remains independent of the test cloth lot used for testing.

2. Definitions

2.1   AHAM means the Association of Home Appliance Manufacturers.

2.2   Bone-dry means a condition of a load of test cloth that has been dried in a dryer at maximum temperature for a minimum of 10 minutes, removed and weighed before cool down, and then dried again for 10 minute periods until the final weight change of the load is 1 percent or less.

2.3   Lot means a quantity of cloth that has been manufactured with the same batches of cotton and polyester during one continuous process.

3. Testing Conditions

3.1   Table 3.1 of this appendix provides the matrix of test conditions. In the table, “g Force” represents units of gravitational acceleration. When this matrix is repeated 3 times, a total of 60 extractor RMC test runs are required. For the purpose of the extractor RMC test, the test cloths may be used for up to 60 test runs (after preconditioning as specified in appendix J1 or appendix J2).

3.2   Perform the standard extractor RMC tests using a North Star Engineered Products Inc. (formerly Bock) Model 215 extractor (having a basket diameter of 20 inches, height of 11.5 inches, and volume of 2.09 ft3), with a variable speed drive (North Star Engineered Products, P.O. Box 5127, Toledo, OH 43611) or an equivalent extractor with same basket design (i.e., diameter, height, volume, and hole configuration) and variable speed drive. Table 3.2 shows the extractor spin speed, in revolutions per minute (RPM), that must be used to attain each required g-force level.

3.3   Bone dryer temperature. The dryer used for bone drying must heat the test cloth and energy stuffer cloths above 210 °F (99 °C).

4. Test Loads

4.1    Preconditioning. New test cloths, including energy test cloths and energy stuffer cloths, must be pre-conditioned in a clothes washer in the following manner:

Perform five complete wash-rinse-spin cycles, the first two with current AHAM Standard detergent Formula 3 and the last three without detergent. Place the test cloth in a clothes washer set at the maximum water level. Wash the load for ten minutes in soft water (17 ppm hardness or less) using 27.0 grams + 4.0 grams per pound of cloth load of AHAM Standard detergent Formula 3. The wash temperature is to be controlled to 135 °F ± 5 °F (57.2 °C ± 2.8 °C) and the rinse temperature is to be controlled to 60 °F ± 5; °F (15.6 °C ± 2.8 °C). Repeat the cycle with detergent and then repeat the cycle three additional times without detergent, bone drying the load between cycles (for a total of five complete wash-rinse-spin cycles).

4.2    Test load composition. Test loads must be comprised of randomly selected cloth at the beginning, middle and end of a lot.

4.3    Test load size. Use a test load size of 8.4 lbs. Two test loads may be used for standard extractor RMC tests, with each load used for half of the total number of required tests.

5. Test Measurements

5.1   Dry the test cloth until it is “bone-dry” according to the definition in section 2.2 of this appendix. Record the bone-dry weight of the test load (WI).

5.2   Prepare the test load for soak by grouping four test cloths into loose bundles. Create the bundles by hanging four cloths vertically from one corner and loosely wrapping the test cloth onto itself to form the bundle. Bundles should be wrapped loosely to ensure consistency of water extraction. Then place the bundles into the water to soak. Eight to nine bundles will be formed depending on the test load. The ninth bundle may not equal four cloths but can incorporate energy stuffer cloths to help offset the size difference.

5.3   Soak the test load for 20 minutes in 10 gallons of soft (<17 ppm) water. The entire test load must be submerged. Maintain a water temperature of 100 °F ± 5 °F (37.8 °C ± 2.8 °C) at all times between the start and end of the soak.

5.4   Remove the test load and allow each of the test cloth bundles to drain over the water bath for a maximum of 5 seconds.

5.5   Manually place the test cloth bundles in the basket of the extractor, distributing them evenly by eye. The draining and loading process must take no longer than 1 minute. Spin the load at a fixed speed corresponding to the intended centripetal acceleration level (measured in units of the acceleration of gravity, g) ± 1g for the intended time period ± 5 seconds. Begin the timer when the extractor meets the required spin speed for each test.

5.6   Record the weight of the test load immediately after the completion of the extractor spin cycle (WC).

5.7   Calculate the remaining moisture content of the test load as (WC-WI)/WI.

5.8   Draining the soak tub is not necessary if the water bath is corrected for water level and temperature before the next extraction.

5.9   Drying the test load in between extraction runs is not necessary. However, the bone dry weight must be checked after every 12 extraction runs to make sure the bone dry weight is within tolerance (8.4 ± 0.1 lb).

5.10   The test load must be soaked and extracted once following bone drying, before continuing with the remaining extraction runs. Perform this extraction at the same spin speed used for the extraction run prior to bone drying, for a time period of 4 minutes. Either warm or cold soak temperature may be used.

5.11   Measure the remaining moisture content of the test load at five g levels: 100 g, 200 g, 350 g, 500 g, and 650 g, using two different spin times at each g level: 4 minutes and 15 minutes.

5.12   Repeat sections 5.1 through 5.11 of this appendix using soft (<17 ppm) water at 60 °F±5 °F (15.6 °C ± 2.8 °C).

6. Calculation of RMC Correction Curve

6.1   Average the values of 3 test runs, and fill in Table 3.1 of this appendix. Perform a linear least-squares fit to determine coefficients A and B such that the standard RMC values shown in Table 6.1 of this appendix (RMCstandard) are linearly related to the RMC values measured in section 5 of this appendix (RMCcloth):

RMCstandard ∼ A * RMCcloth + B

where A and B are coefficients of the linear least-squares fit.

6.2   Perform an analysis of variance with replication test using two factors, spin speed and lot, to check the interaction of speed and lot. Use the values from Table 3.1 and Table 6.1 of this appendix in the calculation. The “P” value of the F-statistic for interaction between spin speed and lot in the variance analysis must be greater than or equal to 0.1. If the “P” value is less than 0.1, the test cloth is unacceptable. “P” is a theoretically based measure of interaction based on an analysis of variance.

7.   Application of the RMC Correction Curve

7.1   Using the coefficients A and B calculated in section 6.1 of this appendix:

RMCcorr = A × RMC + B

7.2   Apply this RMC correction curve to measured RMC values in appendix J1 and appendix J2.

[80 FR 46786, Aug. 5, 2015]