APPENDIX C.

DEVELOPMENT OF A STANDARDIZED ENERGY TEST CLOTH

Report: Development of a Standardized Energy Test Cloth Report for Masuring

Remaining Moisture Content in a Residential Clothes Washer

Appendix A: Test Data

Appendix B: Summary of Extractor Based Test Data

Appendix C: Procedure for Using RMC Correction Factors in Clothes Washer Efficiency Tests

EE-RM-PET-100 COMMENT 88
Development of a

Standardized Energy

Test Cloth for

Measuring Remaining

Moisture Content in a

Residential Clothes

Washer

U.S. Department of Energy

Buildings, Research and Standards

May 2000

Prepared by:

Arthur D. Little, Inc.

Acorn Park

Cambridge, Massachusetts

02 140-2390

EE-RM-PET-100 COMMENT 88
Table of Contents

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1 Introduction 1-1

1.1 Background 1-1

1.2 Energy Test Cloth 1-2

1.3 Moisture Absorption and Retention in an Energy Test Cloth 1-3

1.4 Summary and Approach 1-3

2. Extractor-Based R]\'IC Testing 2-1

2.1 Purpose of Test Program 2-1

2.2 Laboratory and Procedure 2-1

2.2.1 Laboratoiy Equipment 2-2

2.2.2 Procedure 2-2

2.2.3 Shakedown Tests 2-3

2.3 Test Cloth Sources 2-3

2.4 Test Matrix 2-4

2.5 Test Results: RMC versus cfg for Different Test Lots 2-6

2.5.1 Comparison of Cloth Lots 2-6

2.5.2 Evaluation ofAlliance Cloth 2-8

2.6 Test Results: Influence of Other Test Variables on RMC 2-9

2.6.1 Effect of Spin Time on RMC 2-9

2.6.2 Effect of Load Size on RMC 2-10

2.6.3 Effect of Soak Water Temperature on RMC 2-11

2.6.4 Effect of Soak Time on RMC 2-13

2.6.5 Effect of Cloth Lfe on RMC 2-13

2.6.6 Effect of Pre-Conditioning on RMC 2-16

3. Results of Washer Based RMC Tests Conducted by Intertek Testing

Services (ITS) 3-1

3.1 Cloth Characteristics and Relation to RMC 3-1

3.2 Discussion of Cloth Characterization Variables 3-1

4. Cloth Characteristics and Relation to RMC 4-1

4.1 Discussion of Cloth Characterization Variables 4-1

4.2 Results of Cloth Characterization Tests 4-2

4.3 Comparison of Cloth Characterization Test Results with RMC Test

Results 4-7

5. RMC Correction Factor 5-1

5.1 Procedure to Calculate Correction Factor 5-2

5.1.1 Standard RMC versus cfg Curve 5-3

5.1.2 Establish RMC versus cfg Values for New Test Cloth 5-3

EE-RM-PET-100 COMMENT 88
Table of Contents

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5.1.3 Least Squares Fit 5-3

5.1.4 Apply to Clothes Washer Test Results 5-4

5.2 Test Data Confirming Correction Procedure 5-5

6. Approach to Obtaining and Verifying Consistent Test Cloth 6-1

6.1 Outline of Proposed Specification 6-1

6.2 Verification 6-2

6.3 Standard Language 6-2

EE-RM-PET-100 COMMENT 88
List of Figures

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Figure 2.1 RMC vs. g for TI and CG Cloth 2-7

Figure 2.2 RIvIC vs. g for all TI loads 2-7

Figure 2.3 RMC for Alliance Cloth before and after Treatment for Removal

of Stain-Resistance Fluoropolymer Surface Finish 2-9

Figure 2.4 RMC vs. Spin Time for 100 and 300g 2-10

Figure 2.5 RMC vs. Load Size at 100 and 300 g's 2-11

Figure 2.6 RMC vs. g for Warm and Cold Soak for Load T12 2-12

Figure 2.7 RMC vs. g for Warm and cold Soak for Load T13 2-12

Figure 2.8 RMC vs. Soak Time in Minutes for Warm and Cold Soak at 115 g. 2-13

Figure 2.9 RMC vs. Number of Wash/dry cycles 2-14

Figure 2.10 Bone Dry Weight vs. Number of "Washes" 2-15

Figure 2.11 Shrinkage of Energy Cloth Used in Cloth Life Tests 2-16

Figure 5-1 RMC Correction to Determine the RMC that would have been

Measured with "Standard" Test Cloth 5-2

Figure 5-2 Linear Correction Curve for TI Lot 4, with Individual Extractor

RMCDataPoints 5-5

Figure 5-3 Linear Correction Curve for TI Lot 5, with Individual Extractor

RMC Data Points 5-5

EE-RM-PET-100 COMMENT 88
List of Tables

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Table 2.1 Equipment used in Extractor Based RMC Tests 2-2

Table 2.2 Summary of Test Lot Status 2-4

Table 2.3 Extractor Based RMC Test Program 2-5

Table 2-4 RMC Values for Different Pre-Conditioning Machine Type 2-16

Table 3.1 ITS Washer Based RMC Results 3-1

Table 4.1 Cloth Characterization Variables 4-2

Table 4.2 Cloth Characterization: Fabric Weight, Thread Count, Yam Number

and Fiber Content 4-4

Table 4.3 Cloth Characterization: Water Retention, Drop Absorbency, Finish,

Repellency and Vertical Wicking Rate 4-5

Table 4.4 Summary of Results from Independent Laboratories 4-6

Table 5-1 Standard RMC vs. g Values and Corresponding New Cloth RMC

Values for Linear Least Squares Fit 5-4

Table 5-2 Correction Coefficients 5-5

Table 5-3 Lot 4 Verification of Correction Factor in Clothes Washer 5-7

Table 5-4 Lot 5 Verification of Correction Factor in Clothes Washer 5-8

Table 2.6.5 Matrix of Extractor RMC Test Conditions 6-5

Table 2.6.6.1 Standard RMC values (RMCstandard) 6-7

iv

EE-RM-PET-100 COMMENT 88
1 Introduction

This report summarizes the result to-date of the investigation, "remaining moisture content"

(RMC) testing, fabric characterization, and correction procedure undertaken to define a standardized

energy test cloth.

1.1 Background

Under the National Appliance Energy Conservation Act (NAECA), energy efficiency standards

and energy test procedures have been established for a wide range of consumer appliances, including

clothes washers and clothes dryers. The energy test procedures for these two laundry appliances

originally were established in 1977 (clothes washers) and 1981 (clothes dryers) (10 Code of Federal

Regulations (CFR) 430, Subpart B, Appendices J and D, respectively). Both specify a 50/50

cotton/polyester blend "energy test cloth" that is used as a simulated wash load for testing clothes

washers and for testing clothes dryers.

The energy test procedure that is currently in effect for clothes washers measures the electric

energy input to the washer and the energy content of the hot water consumed by the clothes washer.

A clothes washer energy factor is defined in terms of the basket volume and the total electric and hot

water energy use. The current efficiency standard is set in terms of this measurement of the energy

factor. The effectiveness of the final spin cycle in removing moisture from the wash load (and

thereby reducing the energy consumption of the clothes dryer) is not measured or considered.

For a number of years, a rulemaking has been ongoing to revise both the test procedure and the

efficiency standard for clothes washers to take moisture removal effectiveness into account. A

revised test procedure was adopted in a Final Rule dated August 27, 1997 (10 CFR 430 Subpart B,

Appendix J and Ji). Revisions to Appendix J are currently in effect, however, Appendix Ji will not

go into effect until proposed efficiency standards into effect. A modified energy factor (MEF) is

defined in Appendix Ji, based on the electric energy input, the hot water energy, and the dryer

energy. Dryer energy is based on the remaining moisture content of a test wash load. The process

to establish the new efficiency standard in terms of the MEF is ongoing.

In the Appendix J 1 test procedure, "remaining moisture content" (RMC) in a test load of the

aforementioned energy test cloths is the measure of water removal effectiveness. Over the

approximately 20 year period that the original clothes washer and clothes dryer test procedures have

been used, no variations or inconsistency of washer or dryer test results had been attributed to

variations in the test cloths. A significant inconsistency in RIVIC test results under the new Appendix

Ji procedure was noted by Alliance Laundry Systems LLC and was brought to the Department of

Energy's (DOE's or Department's) attention in a letter dated June 7, 1999. In the tests referred to

in this letter, which were run at Intertek Testing Services (ITS), the RMC values that were obtained

in one machine with two different lots of energy test cloths differed by over 11 percentage points

(67.9 percent versus 56.0 percent). When these two lots of energy test cloth were run through a

second machine, a similar difference in RN/IC occurred.

1-1

EE-RM-PET-100 COMMENT 88
The effect of RMC on MEF can be substantial, particularly for washers which are more efficient

with respect to electrical consumption and use of hot water. The following scenario illustrates: For

a high efficiency horizontal axis washer, an 18% increase in RMC (54.5%-64.5%) will result in a

13% decrease in MEF (1.52-1.33). For a lower efficiency washer, a 17% increase in RMC (57.7%-

67.7%) will result in only a 6% decrease in MEF (.82-.77).

1.2 Energy Test Cloth

A wide variety of articles and fabrics are machine washed by consumers, including:

Cotton knit goods, denim, towels

Cotton/polyester blends in shirts, sheets, tablecloths

Various synthetics in a wide variety of articles

It is clear that all of the above could not be evaluated in the revised procedures that include

moisture content. As mentioned above, to simplify RMC testing, the standardized cloth used

successfully in previous energy tests was specified. A number of qualified vendors have been

providing these test cloths to manufacturers and other test labs on an ongoing basis for many years.

The specifications stated in the energy test procedure are:

• A 50/50 cotton/polyester to represent a rough average of the typical mix of cotton,

cotton/polyester blend, and synthetics. The cloth has a momie or granite weave and a pure

bleached finish.

The thread count shall be 61 x 54 (warp x fill) per inch

• The fabric weight shall be 5.75 oz. per sq. yd. (195.0 gm. per sq. m.)

Aside from the historical success with respect to previous procedures, there is no justification for

these specifications.

The energy cloths are 24 in. by 36 in. (61.0 cm by 91.4 cm.) and are henirned to 22 in. by 34 in.

(55.9 cm. by 86.4 cm.) before washing. Energy stuffer cloths (smaller cloths used to even-out load

size) are 12 in. by 12 in. (30.5 cm. by3O.5 cm.)andarehemmedto 10 in. by 10 in. (25.4 cm. by25.4

cm.) before washing. Both energy test cloths and stuffers cloths should shrink no more than 4% on

the length and width after five washes.

Cloth manufacturers typically produce yarn from fiber and subsequently weave and finish the

cloth material. Two suppliers, Textile Innovators Corp. (TI) and Cotton Goods Mfg. Co. Inc. (CG)

1-2

EE-RM-PET-100 COMMENT 88
purchase cloth material, prepare the energy cloth by sewing and hemming and provide it to washer

manufacturers and testing laboratories. They have supplied energy test cloth that, over the years, has

varied somewhat from the above standards.

There are additional cloth specifications that influence the moisture content. The yarn size is a

parameter that is related to the yarn diameter. This, together with thread count, blend (fiber content)

and weight define the porosity of the cloth. Finish, referred to by descriptors such as "pure bleached"

must be clearly identified. Any finish, particularly a water repellant finish (frequently specified for

cloth used in other applications), must be avoided.

1.3 Moisture Absorption and Retention in an Energy Test Cloth

The amount of water absorbed and retained in an energy test cloth can be attributed to several

factors:

Surface wetting, which is a function of relative humidity

Water retained between the warp and fill

Water retained between the fibers

Water retained in the lumen, or center of the cotton fiber

Water ionically bonded in the cotton fiber

Polyester is hydrophobic, and essentially has no attraction for water. All of the factors listed,

except ionic bonding, are effected by the mechanical removal process. Water that is ionically

bonded can only be removed chemically or by heating. Since RMC tests are only mechanical,

there is a limit to the moisture that is removed.

1.4 Summary and Approach

It is apparent that a standardized test cloth is required in order to provide consistent RMC test

results. The work summarized herein is aimed at:

• Identifying the variables in the construction of 5 0/50 polyester cloth and its constituent fiber

and yarn that affect the moisture absorption and moisture retention characteristics of the

cloth

• Developing a process for obtaining and validating standard test cloth

• Generating data that indicates the sensitivity of RMC values to different operating variables

and reporting them in a publicly available document

1-3

EE-RM-PET-100 COMMENT 88
This report summarizes our efforts to date in addressing these issues. Our approach includes

the following tasks:

In-house laboratory testing using an extractor to obtain effects of operating variables on RMC

for cloth from different suppliers and different lots from the same supplier

Analyze cloth samples using external testing laboratories

Use information from above to:

• Document the effect of variables on RMC

• Propose a procedure to obtain and verify consistent test cloth

• Propose a revised definition of test cloth for regulations

Details on progress are found in the following report.

1-4

EE-RM-PET-100 COMMENT 88
2. Extractor based RMC Testing

To understand the effects of operating variables and cloth specifications, it is necessary to

conduct laboratory tests to determine RMC. To insure that test results would not be influenced or

biased by any manufacturer's product (clothes washer), we used an extractor to remove moisture

content. An extractor is a centrifuge - basically a rotating basket that has a controllable speed to

produce a variety of centrifugal forces. The speed was varied to impose different centripetal

accelerations on the test load. These accelerations are reported in terms of gravitational acceleration

(g). We also chose to soak the cloth in a tub at controlled temperature rather than use the agitated

soak cycle provided by a typical washer. Otherwise, our RMC tests closely resembled those specified

in the energy test procedure.

2.1 Purpose of Test Program

The extractor-based RMC tests have two basic purposes:

To evaluate the differences in spin g vs. RMC for available test cloths from different suppliers

and different lots from the same supplier. Ultimately, relate these variations (or lack of variation)

to differences in cloth specification that can be ascertained by laboratory tests (as explained in

Section 4.). Determine whether differences in RMC vs. g in the extractor test correlate with

differences in RMC in a particular clothes washer as obtained by Intertek Testing Services (ITS).

2. To evaluate the impact of several basic variables on RMC results and the consistency!

repeatability of RMC results when identical cloth is run under identical conditions using an

extractor. Variables to be studied are:

• Effect of spin time on RMC

• Effect of soak water temperature prior to spinning on RMC

• Effect of length of soak time prior to spinning on RMC

• Effect of load weight/basket volume on RMC

• Effect of test fabric life (cumulative wet - dry cycles) on RMC and shrinkage

Quantitative data addressing each of these variables and repeatability under identical test

conditions will be indicative of which variables need to be closely controlled in future testing and/or

where bounds need to be established to ensure consistent results.

2.2 Laboratory and Procedure

This section discusses our extractor-based RMC testing laboratory and procedures. Also

included is a description of shakedown tests used to verify testing procedures and establish initial

test parameters.

2-1

EE-RM-PET-100 COMMENT 88
2.2.1 Laboratory Equipment

Table 2.1 details major equipment used in our extractor-based RMC studies. As noted, our

preferred extractor had a long delivery time, so a smaller unit with immediate availability was

initially utilized.

Table 2.1 Equipment used in Extractor Based RMC Tests

II LM J SII( fllCAi1ON J S[PPLIF1 I>1iriuosE J

Washing Machines (2) Typical, 3 speed, 14 Local supplier For initially preparing cloth for extractor.

cycle, 2.9 ft3 Two machines of identical construction.

(Maytag Model #

_________________

LAT97O6AAE) ____________

Clothes Diyer 90000 BTU/hr, gas Local Supplier

_______________________________

A commercial size dryer to insure "bone

____________________

fired ______________dry" cloth.

Extractor 35 lb. capacity, 20 in. Bock This extractor is sized to satisfy all test

diameter, 11 .5 in. Engineered requirements.

depth, with variable Products

______________________ speed drive

Extractor 20 lb. capacity, 17 in. Smart-Sox, Inc. This is a smaller extractor, purchased

diameter, 10.5 in. because of its immediate availability. It

______________________ depth ________________ was used for initial testing.

Power Inverter MagneTek, 3 hp, 3 Blanchard Required to operate the smaller extractor at

phase, 220 volts Electric, Inc. variable speed.

______________________

Water Heater 40 gallon capacity In-house Required for 135F wash water.

Scales 26 lb. +1- .00022 In-house Required for weighing cloth.

____________________

lb.480 lb. +1- .01 lb.

______________ ____________________________________

2.2.2 Procedure

Our procedure closely resembles those in the existing energy test procedure. We have a pretest

procedure to both precondition the cloth and the clothes washers. Test loads are preconditioned once

unless otherwise noted. A series of extractor-based RMC tests is then performed on the test load at

specified conditions.

Pretest Procedure

1. Test lots of cloth (energy test cloth and stuffer(s)) from different sources are divided into test

loads. Each cloth is marked with the test load number in indelible ink.

2. Clothes washers are preconditioned per Appendix Ji: Section 2.9 (Ji :2.9)

3. Inlet hot and cold water temperatures are recorded. Hot water is maintained at 135F +1- 5F.

2-2

EE-RM-PET-100 COMMENT 88
4. Each load is prewashed:

2 complete cycles: warm prewash! warm wash w/AHAM detergent and 2 warm rinses

and drying

3 complete cycles: warm normal wash and warm rinse and drying

5. Each load is made bone-dry per Ji :1.3.

RMC Test Procedure

Each extractor-based RMC test is conducted using the following procedure:

1. Record the bone-dry weight.

2. Soak in a cylindrical vessel 16" in diameter containing approximately 10 gallons of water.

Soak temperature is either cold (60F ±.5F) or warm (100F ±5F) and time is variable.

3. Remove the load and place carefully in the extractor without wringing the cloth.

4. Run the extractor at the prescribed g and time.

5. Remove the load and record the weight.

6. Compute %RMC as follows: % RMC= [(Weight after extraction - bone-dry weight) / bonedry weight] * 100

7. Bone-dry the load and repeat steps 1-7 as prescribed in test plan.

2.2.3 Shakedown Tests

We conducted shakedown tests to verify the above procedures and to establish parameters for

our initial tests. The load size was 4.5 lbs., which represented a mid-sized load for a washer with the

dimensions of our initial extractor. Other parameters included soak time and spin time. A soak time

of 20 minutes and spin time of 10 minutes was selected for the initial tests.

2.3 Test Cloth Sources

Our test cloth is obtained primarily from Textile Innovators Corporation. (TI) and Cotton

Goods Manufacturing Company, Inc. (CG). To date, five lots (orders) have been received from

TI and two lots from CG. In addition, cloth was distributed as follows:

A portion was sent to Intertek Testing Services Inc. (ITS) for washer-based RMC tests.(see

Section 3)

2-3

EE-RM-PET-100 COMMENT 88
Samples from each lot were sent to independent laboratories for determination of cloth

characteristics (see Section 4).

A small portion of TI lot 3, and a larger portion of TI lot 5 was sent to each washer

manufacturer for in-house laboratory testing.

In addition, we performed extractor-based RMC tests on cloth received from Alliance

Laundry Systems LLC. It was suspected that a fluorochemical finish was present on this

material. Consequently, as detailed below, we tested this cloth both as received and also after a

finish removal process was conducted.

Table 2.2 summarizes the status of test lots.

Table 2.2 Summary of Test Lot Status

Lo md Load deoIiIintion

__________________________ J

Tci. Loads

cr Lot ]

RI( ct IFS 1 cssing

j

haatcrstLcs

Tes a LaL

Maiiu1ac1iirer

TI Lot 1, (ADL 1) 2 C C C N

TI Lot 2, (ADL 2) 1 C C C N

TI Lot 3, (ADL 3) 1 C C C C

TI Lot 4, (ADL 4) 1 C N C N

TI Lot 5, (ADL 5) 1 C P C C

CGLotl 2 C C C N

CGLot2 1 C N N N

Alliance Initial 1 C C C N

Alliance Treated 1 C C N N

KEY TO TABLE: C = Complete, P = planned, N not planned

2.4 Test Matrix

A test program was designed to carry out the objectives outlined in Section 2.1. As indicated

in Table 2.3, the program was divided into a series of tests. The first two series of tests were

intended to evaluate the differences in RIvIC vs. spin g with respect to test lots. We also tested

the Alliance load with and without a fluorochemical finish. In the remaining tests, we evaluated

the effect of variables (in addition to g) on RMC results. These variables included:

Spin time

Load size

Soak water temperature prior to spin

Soak time prior to spin

Cloth life (cumulative wash cycles, shrinkage)

2-4

EE-RM-PET-100 COMMENT 88
The Appendices include a list of all test results included in this report.

Table 2.3 Extractor Based RMC Test Program

( kUt 1.D.

________________

[

S)H-I

j

{ Spu. Timi',

rniu

Soak

j TemP.

] SoI 1 iiin.

mum.

I..od

size. lb.

Piir' of ie

TIl, CG1, 100 10 Warm 20 4.7 Evaluate RMC vs. g for Lots

CG2 300 from different Suppliers

___________ 500 _____________ __________ _____________

TIl, T12, 50 15 Warm 20

_________

8.4

_________________________

Evaluate RMC vs. g for Lots

T13 100 from the same Supplier

200

300

500

___________ 800 _____________ __________ _____________ _________

Alliance 100 10 Warm 20 4.7

_________________________

Effect of Finish Removal on

Initial and 300 RMC

Treated 500 _____________ __________

100, 2 Warm

_____________

20

_________

8.4

_________________________

Effect of Spin time on RMC

4

TIl,T12 300 6

10

15

20

___________ ________ 25

T12 100, 15

__________

"Wash"*

_____________

"Wash"*

_________

3

_________________________

Effect of Load Size on RMC

4.7

300

____________ _________ ____________ 8.4

T12, T13 50 15 Warm, 20 8.4

________________________

Effect of Soak Temperature

100 Cold on RMC

200

300

500

____________ 800 ______________ ___________

TIl 115 10 Warm,

______________

10

_________

4.7

___________________________

Effect of Soak Time on

20 RMC

Cold 60

120

__________ _______ ____________ _________ 16 hr.

T12, T14,

T15

100 15 "Wash"* "Wash"*

________

8.4

_______________________

Effect of Cloth Life on RMC

(50 "washes" with RMC

determined after every fifth

"wash")

T13, T14, 50 4 Warm, 20 8.4 Obtain data for generation of

T15 200 15 Cold correction curves

___________ 350 _____________ __________

* A "wash" consists of an agitation. sninning lightly and

_____________ _________

a second agitation with no d

_________________________

etergent and warm water in a

washer

2-5

EE-RM-PET-100 COMMENT 88
2.5 Test Results: RMC vs. g for Different Test Lots

This section discusses the differences in RMC vs. spin g with respect to different cloth suppliers.

We report results for cloth from the two suppliers, TI and CG, as well as evaluation of the Alliance

cloth that was suspected to have a fluorochemical finish. Below, we first compare the TI and CG

lots, discuss differences between lots, and finally address the Alliance lot.

2.5.1 Comparison of Cloth Lots

Comparison of TI and CG lots is shown on Figure 2.1. These data (taken in the smaller, SmartSox extractor) are with a spin time of 10 mm., warm soak temperature, 20-mm. soak time and a 4.7

lb. load. As expected, there is a clear decrease of moisture content with higher g. Typical vertical

axis washing machines produce spin g's in the range of 120 g's. The asymptotic value at high g

represents the maximum amount of moisture that can be mechanically removed from cloth. (see

Section 1.3) The CG cloth clearly has higher RMC with decreasing differences at higher g values.

At 100 g's, the lot-to-lot variation of the TI loads was 2% RMC, while the CG to TI difference is

11%. The two cloths had a different "feel", the CG cloth feeling much smoother than the TI cloth.

In Section 4, we present laboratory results indicating that TI and CG cloth had some differences in

characteristics. However, there is no clear connection between these differences and RMC. Further

investigation indicated that the CG cloth and TI cloth came from different manufacturers. The TI

cloth was purchased from Riegel Mills, which produces finished product (cloth) from raw material.

The mill that produced the CG cloth is unknown. CG obtained their cloth from Artex, a distributor

that purchases cloth from mills and resells it to users. Our conclusion is that, in this case, differences

in RMC could not be easily explained by examining cloth specifications. Water absorption and

retention may change with manufacturers who are supplying material with similar characteristics.

Identifying the mill of origin may help determine these differences. This may suggest that a single

manufacturer of energy cloth may be desirable.

2-6

EE-RM-PET-100 COMMENT 88
70%

65%

60%

55%

50%

45%

40%

35%

30%

25%

20%

Load Size: 4.7 lbs.

Soak Time: 20 Mm.

Soak Temp: Warm

Spin Time: 10 Mm.

-'-TIlA

-CG1A

-*-Tll B

-*-CGIB

0 100 200 300 400 500

9 Factor

Figure 2.1 RMC vs. g for TI and CG Cloth

60.0%

55.0%

Soak Temp: Warm

20.0%

600

---ADL I

ADL 2

-*-ADL 3

- ADL4

•i-AOL 5

0 100 200 300 400 500 600 700 800 900

g

Figure 2.2 RMC vs. g for all TI loads

2-7

EE-RM-PET-100 COMMENT 88
Also of interest is the difference between lots supplied by the same manufacturer. Figure 2.2

shows data for five TI lots (ADL1 -5). These data (taken in the Bock extractor) are all with a spin

time of 15 minutes, warm soak temperature, 20-minute soak time and an 8.4 lb. load. For the first

three lots tested ADL1, ADL2, ADL3, there is a maximum data spread of about 2 percent.

Subsequent lots 4 and 5 varied significantly as shown.

2.5.2 Evaluation of Alliance Cloth

As part of our test program, we were asked to perform RMC tests on cloth supplied by Alliance

Laundry Systems LLC. They had purchased this cloth from TI and obtained inconsistent results in

their in-house tests, i.e., RMC was lower than expected. It was suspected that a fluorochemical finish

that would repel moisture was present on this material. This was verified by laboratory tests

performed by Minnesota Mining and Manufacturing Company (3M). We tested this cloth as received

and also after a finish removal process.

A procedure recommended by the United States Department of Agriculture (USDA) Laboratory

(Southern Regional Research Center) for removal of finish was p8rformed. The procedure called for

a mixture of Triton X- 100, Trisodium pyrophosphate, and Tide to be mixed at a concentration of

1 gram/Liter, each. The test load was then soaked for one hour at 200 to 212 °F. The results are

shown in Figure 2.3. These data are with a spin time of 10 minutes, warm soak temperature, 20

minute soak time, and a 4.7 lb. load (taken in the smaller, Smart-Sox extractor). The results show

that the RMC values were higher in the treated cloth, but not to the extent expected with finish

removal. The conclusion is that the fluorochemical finish was not removed by the process or that

the fluorochemical finish was not responsible for the differences in RMC. Since the removal process

is used routinely by USDA, we suspect the latter conclusion is correct.

2-8

EE-RM-PET-100 COMMENT 88
0

Figure 2.3 RMC for Alliance Cloth before (ASG) and after Treatment for Removal of

Stain-Resistance Fluorochemical Surface Finish (ASG Stripped)

2.6 Test Results: Influence of other Test Variables on RMC

The data in the previous section shows that the RMC is strongly influenced by spin g level.

Several other operating variables also influence the RMC level reached after a spin cycle:

• Spin time

• Load size

• Soak water temperature prior to spin

• Soak time prior to spin

• Cloth life (cumulative wash cycles, shrinkage)

The primary focus of the work reported herein has been to develop a test cloth specification, so

that consistent RMC values are obtained with different lots of test cloth. In pursuit of this objective,

it is of interest to understand the quantitative magnitude of the effect of these variables on RMC

levels; it is further of general interest to have this information publicly available.

2.6.1 Effect of Spin Time on RMC

For a fabric and load size, at a given spin g level, there appears to be an equilibrium RMC

level that is reached after a comparatively long spin time. This is the limit of the mechanical removal

2-9

o 100 200 300 400 500 600

g Factor

EE-RM-PET-100 COMMENT 88
process for that g force. Figure 2.4 plots RMC vs. spin time for two different lots at 100 and 300 g.

These data represent TIl and T12 loads with warm soak temperature, 20-minute soak time, and an

8.4 lb. load. The figure shows evidence of dependence of spin time on RMC. The equilibrium time

at 300g (about 20 minutes) appears to be somewhat longer than at 100 g (about 15 minutes). There

is, of course, more moisture removed at higher g. The process (see Section 1.3) involves several

mechanisms with effectiveness that varies with g, apparently resulting in somewhat longer

equilibrium times as more moisture is removed.

-

55%

50%

45%

40%

C)

35%

30%

25%

20%

-*-Tl Lot 1 (300 g)

--TI Lot 2 (300g)

-

--A-TI Lot 1(1009)

K TI Lot2 (1009)

Load Size: 8.4 lbs.

Soak Time: 20 Mm

Soak Temp: Warm

0 5 10 15 20 25 30

Spin Time (mm)

Figure 2.4 RMC vs. Spin Time for 100 and 300g.

2.6.2 Effect of Load Size on RMC

RMC vs. load size is plotted in Figure 2.5 at 100 and 300 g's respectively. These data were

taken in conjunction with our tests on cloth life (see Section 2.6.5). The three load sizes represent

the minimum, average, and maximum load size recommended for the extractor drum volume. The

normal soak process was replaced by a "wash" that consisted of an agitation, light spin and a second

agitation. No detergent and warm water was used. This was followed by the extractor-based spin.

For these tests, the spin time was 15 minutes and the spin g was 100 and 300. Figure 2.5 shows the

RMC decreases by several percentage points with increasing load at an amount that is independent

of g force. This is possibly due to the increased pressure on the outer cloths in the basket caused by

the increased radial depth of the load. It suggests that the load size and extractor dimensions

(diameter, depth and perhaps basket porosity) be specified for RMC tests.

2-10

EE-RM-PET-100 COMMENT 88
55%

50%

45%

40%

C.)

35%

30%

25%

20%

152.9%

"9.4%

.46.6%

0355%

e335%

31.5%

TI 1967 (Lot 2)

Spin Time: 15 Mm.

0 1 2 3 4 5 6 7 8 9 10

Load Size (lb.)

Figure 2.5 RMC vs. Load Size at 100 and 300 g's

2.6.3 Effect of Soak Water Temperature on RMC

The RMC is generally higher when the rinse water temperature is lower. Figures 2.6 and 2.7

show RMC vs. g for T12 and T13 loads respectively at warm (100°F) and cold (60°F) soak

temperatures. The spin time was 20 minutes, soak time was 20 minutes and the load was 8.4 lb. Two

figures are provided since the effect of temperature is difficult to discern when compounded with

the data spread with load. Similar results were obtained with future lots 4 and 5. The cold water

RMC values are as much as 8%, but generally 2-3% higher than the warm water RMC values. This

is perhaps attributable to the temperature dependence of the surface tension and the absorptivity of

water in cotton (both decrease with increasing temperature).

2-11

EE-RM-PET-100 COMMENT 88
5

5

4

4

0

3

3

2

20%

0 100 200 300 400 500 600

g Factor

Figure 2.6 RMC vs. g for Warm and Cold Soak for Load T12

55%

5

4

4

0

3

3

2

20%

0 100 200 300 400 500 600 700

g Factor

Figure 2.7 RMC vs. g for Warm and Cold Soak for Load T13

2-12

700 800 900

800 900

EE-RM-PET-100 COMMENT 88
2.6.4 Effect of Soak Time on RMC

In actual RMC tests, a washer is used and the soak time also includes agitation. As explained

earlier, for our extractor based RMC tests, we soak the cloth in a cylindrical tub containing 10

gallons of water. During our shakedown tests, we determined the effect of soak time on RMC. Figure

2.8 shows results for warm and cold soaks. The data are for TI cloth, 115 g, 10-mm. spin time and

a 4.7 lb. load. The data show no discernable trends in RMC vs. soak times for cold soaks. There

appears to be an increase in RMC with soak times of warm soaks for time greater than 1 hour. In

order to resemble, to some extent, actual washer soak time and to maintain reasonable test times, we

selected 20 minutes as soak time for our tests.

70%

60%

50%

40%

C,

30%

20%

10%

0%

L

S

S

oad Size:

pin Time

pinSpee

4.7 lbs

: 10 Mn

d: 115g

.

. DTl 1 Warm*

Tl 1 Cold*

-

'

Ii_

-FI

I, __ _=

_

I

10 20 60 120 16 Hours

_4_

Soak Time

Figure 2.8 RMC vs. Soak Time in Minutes for Warm and Cold Soak at 115 g.

2.6.5 Effect of Cloth Life on RMC

To determine the effect of cloth life or cloth durability on RMC, we repeatedly "washed" a load

of cloth and periodically performed RMC tests (omitting soak time). Our "wash" cycle includes

agitation, spinning lightly and a second agitation with warm water, all with no detergent. Other

portions of a normal wash cycle are presoak and spinlrinse. The presoak is optional and we

considered the spin/rinse taken care of in the RMC test. We "washed" the load 5 times, then

performed an RMC test and repeated this process 10 times, ultimately completing 50 "washes".

Results for RMC change with "washes" and the change in bone dry cloth weight with "washes" are

2-13

EE-RM-PET-100 COMMENT 88
shown in Figures 2.9 and 2.10, respectively. The data are for TI cloth, at 100 g, with 15-mm. spin

time, and an 8.4 lb. load. The cloth weight is reduced approximately 2% in 50 "washes" because of

the continual removal of material in the washing process. The RMC increases on the order of 1%

in 50 "washes". The rate of weight loss from the fabric and the rate of RMC increase were linear

over the entire 50 wash cycles. Neither showed any sign of increasing toward the end of the 50 wash

cycles. The conclusion is that the cloth appears to hold slightly more moisture as it ages. This is

possibly due to greater voids created in the cloth with age. Note that the DOE test procedure allows

test cloths to be used for up to 25 wash cycles.

60%

58%

56%

54%

52%

35

50%

48%

46%

44%

42%

40%

D

Lot4 - -

a a

Lot5 .

Load Size: 8.4 lbs.

Spin Time: 15 Mm.

Spin Speed: bOg

0 10 20 30 40 50 60

# Washes

Figure 2.9 RMC vs. Number of Wash/dry cycles

2-14

EE-RM-PET-100 COMMENT 88
3950

3900

3850

a)

3800

3750

3700

3650

0 5 10 15 20 25 30 35 40 45 50 55 60 65

Wash #

Figure 2.10 Bone Dry Weight vs. Number of "Washes"

As part ofthe fabric life testing the test cloth shrinkage was monitored. Linear dimensions were

taken in three locations on both the horizontal and vertical axis of the test cloth. The unwashed test

cloth dimensions established the baseline. Measurements were recorded after each of the five preconditioning washes and then after every ten wash cycles. The results are shown in Figure 2.11. The

percent shrinkage increased steadily during the pre-conditioning process, reaching a plateau after ten

wash cycles. The variation in percent shrinkage between lot 4 and lot 5 was nearly consistent at 1%.

There is no compelling evidence that the percent shrinkage has an impact on the moisture retention

of the test cloth. With the improved test cloth specification and more robust pre-conditioning

procedure, it is suggested that the shrinkage requirement be removed from the test procedure.

2-15

EE-RM-PET-100 COMMENT 88
8.0%

7.0%

6.0%

5.0%

0C

• 4.0%

Ci,

3.0%

2.0%

1.0%

0.0%

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

# Washes

Lot 4

lLot 5

Figure 2.11 Shrinkage of Energy Cloth Used in Cloth Life Tests

2.6.6 Effect of Pre-Conditioning on R1\'IC

The pre-conditioning procedure was verified using both a vertical and horizontal axis washing

machine to determine ifthe machine type used in pre-conditioning impacts the RMC results. TI Lot

4 and Lot 5 were each pre-conditioned following the procedure described in section 6.3, subsection

2.6.3. Each load was then mn in the extractor to compare RMC values. The extractor tests were

performed, as previously, with a 20 minute warm soak, 15 minute spin, at 100 g. The results, shown

in Table 2-4, show nearly identical RMC results regardless of the pre-conditioning machine type

used. Based on these results, specification of a pre-conditioning machine type is not necessary.

Table 2-4: RMC Values for Different Pre-Conditioning Machine Type

R1abirw 1pe J Io 4 - ]

Vertical 53.3% 50.1%

52.1% 51.0%

Horizontal 53.1% 50.9%

52.3% 50.3%

53.0% 50.5%

2-16

EE-RM-PET-100 COMMENT 88
3. Results of Washer Based RMC Tests Conducted by Intertek Testing (ITS)

Since ITS is an independent laboratory that routinely does washer based RMC testing for the

industry, it was decided to send cloth to them from the same lots we used in our extractor-based

RMC tests for evaluation. This would allow a comparison of washer-based RMC to extractor-based

RMC. The results of ITS washer based RMC tests are given in Table 3.1. The ITS tests are done on

two washers, listed as Amana and Whirlpool. The loads that originated the study are listed as

Alliance (origin TI) and ITS (origin CG). Our (ADL) cloth came from lots used in our RMC tests

discussed above. The lots were purchased at different times from the supplier listed. The dramatic

difference between the Alliance and ITS loads is also evident in the ADL data, suggesting that the

discrepancies in RMC between TI and CG cloth is independent of lot. There is about 5% maximum

difference in the TI lots per machine and up to a 7 % difference between machines. A comparison

of values between those in the table and Figure 2.1, extractor-based results, indicates a similarity in

trend. Numerical values cannot be compared because of the differences in test methods, i.e., washerbased vs. extractor-based.

Table 3.1 ITS Washer-Based RMC Results

Mliaitce kflL. Til MW II. AIDL 113 ET AIL CCI

Amana 56.0% 55.21% 52.28% 53.09% 67.9% 66.09%

Whirlpool 53.7% 54.65% 51.56% 49.58% 64.9% 63.84%

3.1 Cloth Characteristics and Relation to RMC

The construction of a textile fabric and its constituent yams is characterized by a number of basic

variables. For a particular fabric, cloth specifications could define the nominal value of these

variables and the acceptable tolerance range. The material that follows is a discussion of these

variables and the likely relationship of these variables to the moisture absorption and retention of the

cloth.

Following the discussion of the variables, the test results are summarized from several labs to

characterize the test cloths that have been examined in this project.

3.2 Discussion of Cloth Characterization Variables

A listing of cloth characterization variables, their descriptions, suspected relation to RMC,

specification in current (proposed) regulation and appropriate test for evaluation is given in Table

4.1. Note that only fabric construction, thread count, fiber content, fabric weight and finish are

currently specified in the proposed regulation.

3-1

EE-RM-PET-100 COMMENT 88
4. Cloth Characteristics and Relation to RMC

The construction of a textile fabric and its constituent yarns is characterized by a number of basic

variables. For a particular fabric, cloth specifications could define the nominal value of these

variables and the acceptable tolerance range. The material that follows is a discussion of these

variables and the likely relationship of these variables to the moisture absorption and retention of the

cloth.

Following the discussion of the variables, the test results are summarized from several labs to

characterize the test cloths that have been examined in this project.

4.1 Discussion of Cloth Characterization Variables

A listing of cloth characterization variables, their descriptions, suspected relation to RMC,

specification in current (proposed) regulation and appropriate test for evaluation is given in Table

4.1. Note that only fabric construction, thread count, fiber content, fabric weight and finish are

currently specified in the proposed regulation.

4-1

EE-RM-PET-100 COMMENT 88
Table 4.1 Cloth Characterization Variables

roper1 Deserpioii Rehtliuii jCuFrenl Fl ioi•

Suspected to Siwcii&atiou IEvaIt1aioL1

___________ _________________________ RMC i I

'abric Veave of cloth. Either momie Jnknown

__________

vlomie

____________

[dentified

Construction granite)- irregularly woven (granite) visually

vith rough surface or plain weave

___________

veave-regularly woven.

farn Type ither open-end or ring spun Jnknown Jnspecified Identified

___________

(open end common today) visually

[hread Count '.Tumber of yams that run

______________

Higher thread

___________

65/57 .STM D 3775:

engthwise (warp or count implies Jhread Counts

nds)/number of yams that nore cotton, er Inch

_____________

nterlace(fill or picks) iigher RMC ____________

iber Content % blend by weight of fiber type vlore cotton fiber 50/50 cotton! ATCC 20A-with

n yam implies higher olyester noisture: Fiber

RIVIC omposition

Tarn Number inear density of yarn, mass/length Thicker thread implies 'Tot specified ,.STM D 1059:

ore cotton , higher Standard Test

IMC 4ethod for Yam

1umber

abric Weight )ry weight per unit area (oz. per sq. yd. or leavier weight implies 5.75 oz. Per sq. .STM D 3776:

ms. per sq. m.) aore cotton, more d. Veight

MC

inish ould cover a variety of finishes applied ny finish would lower 'ure finished tATCC TM 94:

o the cloth (related to final uses or IMC leached inishes in Textiles:

acilitating manufacturing process) dentification

Vater Retention mount of water retained in a centrifuge Vater retention 'Tot specified STM D 2402:

est increases RJvIC Vater Retention by

mbibition

bsorbency mount of time for a drop of water to bsorbency increases 'Tot specified ATCC TM 79:

bsorb MC thsorbencyof

leached Textiles

Tertical Wicking 'ime for water to travel a fixed distance up aster wicking implies 'Tot specified [ertical Wicking

Late he cloth. Tested in the warp and fill Ligher RMC tate

irections

Lepellency to Oil f a surface is wetted by oil or water. lepellency lowers 'Tot specified ATCC TM 118:

nd Water dentifies fluorochemical and other MC )il Repellency

inishes

4-2

EE-RM-PET-100 COMMENT 88
4.2 Results of Cloth Characterization Tests

Tables 4.2 and 4.3 present results from the independent laboratories for the cloth

characterization tests. As shown, there is an absence of data in some cases. Either the data was not

requested or the laboratory was unable to perform the required tests. Also there are some

discrepancies in the reporting and/or method of analysis (see results for water retention). Information

on fabric construction and yarn type is particularly sparse. Vartest reported the weave on both CG

and TI samples to be "crepe weave" (not momie), CG to be "ring-spun" yarn, and TI to be "openend" spun yarn.

4-3

EE-RM-PET-100 COMMENT 88
Table 4.2 Cloth Characterization: Fabric Weight, Thread Count, Yarn Number and Fiber

Content LF bric nipI Ii) lci L;iI' FIjcid. Cii pit Iai ii Ntunbrr ' liur (o ii

fiiiIrce j Warp lu! WarI, ii ji iUon

04 N]v% j

'extile 'Alliance" CTS .86 5.0 0.0 9.58 50.2

nnovators ntertek .90 7.20 1.00

_______ -

-9.8 19.5

_____________ 5.2 7.00 2.00

______

-0.2 19.8

JSDA 58! 1.00 7.00

______

16.90 16.20 1.9 18.1

____________ 584 _______

Tartest 5.90 6.20

_______

1.00

______

-

_______

0.53

_______

19.47

_____________ ____________

.98 6.70 1.00

______

______ -0.24 19.76

DLLotl (TI!) /artest 5.60 4.80 5.00 16.20 15.5 1.2! 18.79

______________ _____________

;.64 4.00 5.30 16.40 16.10 0.7 19.3

iDLLot2 (TI2) ntertek .3 0 4 16.0 16.0 2.6 7.4

_______________ Tartest .23 0.5 3.5 16.3 15.8 8.5 1.5

DL Lot 3 (T13) CTS .3 2 3 16.3 15.8 18.5 1.5

ntertek .3 1 3 15.9 15.9 1.5 L8.5

______________ Tartest .33 1.7 4.0 15.8 15.5 0.09 9.9!

WL Lot 4 (T14) CTS .87 3 3 14.6 14.7 0.5 .9.5

ntertek .9 5.6 3.6 15.! 14.3 1.6 .8.4

______________

Iartest .62 4.3 530 16.7 15.! 1.76 .8.24

DLLot5 (T15) CTS .5 3 2 15.4 14.5 0.7 9.3

ntertek .89 6.0 540 15.2 15.2 i2.0 .8.0

___________ ______________ Tartest 44 3.3 53.0 15.3 15.0 il.76 .8.24

otton Goods TS CTS .73 0.00 51.00 ______ 5.1 4.9

ntertek .90 0.60 54.00

-

7.2 2.8

____________

.80 0.40 52.40

______

______

-

8 2.0

JSDA .67 3.00 /1.00 18.10

-

17.50 7.8 2.2

______________

.75

Tartest .88

________

9.70

________

53.00

_______ ________

8.32

________

1.68

______________ _____________

.88 1.00 54.30

_______

.8.32 1.68

Tartest .20 7.30 6.00

______

18.00 18.10 4.27 .5.73

__________ _____________ ____________ .24 7.00 5.50 1730 lQ 4.02 5.98

4-4

EE-RM-PET-100 COMMENT 88
Table 4.3 Cloth Characterization: Water retention, Drop Absorbency, Finish, Repellency and

Vertical Wicking Rate

trre

coHrce

i thplt ID Ls ii aer

I!L1Iii(1II

)iôp

.U)S()1LIIIV,

Fjpjiji Repk.ILy,

I )5OI),

:SiI

Vi?r ital

%%ICIdNI, see.

(ii Clii

____________ ______________ ___________ ____________ _______________ Vtt'r warn

rextile 'Alliance" ISDA 15.5 388

_______________________________

________________________ (58 99

nnovators ________

15.2 153 _____________________

______ -

Iartest _________ ___________ ________________________

_____

)

-

)

_____ ____ ____ _____ )

--

\.DL Lot 1

TIl)

Iartest 191 .8

__________

'ossible lubricant or

urfactant

___

)

185 .8 'ossible lubricant or

surfactant

)

\DL Lot 2 ntertek 8.0

T12) Iartest 196.6 .9 'olyvinyl Acetate ) ) 0 0

DL Lot 3 \CTS 13.75 .1 ________________________ ) )

T13) ntertek _________

'.4 ________________________

--

___________ Jartest 226.68 .6 one

_______

) )

--

0

WL Lot 4 CTS ________

:1 _______________________ ) )

T14) ntertek ________ .6 _____________________

--

___________ Jartest ________ 1.9 _______________________

______

)

-

)

-

DL LotS CTS ________

:1 _______________________

--

T15) ntertek ________ 1.2 _______________________

______

) )

________ __________ /artest ________ 1.4 ) )

-

otton TS ________ ________ __________

_____________________ -

joods _____ ______

_______________________ ______

______________ ____ -

JSDA 18.4 :1 _______________________ 15 12

________ 17.2 :1 ______________________

______ -

Tartest _________ ___________ _________________________

______

) )

_____ ____ ____ _____ ) )

-

Gl Jartest 92 .4

___________

Vax, Silicone/polyester

ligomer, Possible lubricant

r surfactant

) )

87 ).5 ossible lubricant or

urfactant

) )

Table 4.4 summarizes the differences found in the laboratory results and provides comments

on conclusions and effect on RMC. Here we discuss only the lots tested in our extractor-based RMC

tests, not the "Alliance" and ITS data.

4-5

EE-RM-PET-100 COMMENT 88
Table 4.4 Summary of Results from Independent Laboratories

Prortv, Diffeieice 1)jfficiici Itweeii 1.)iftruos (oicIuiii aTI reIiioit tn

jL5, saifl ippIiip JH^IweeII C( tnd R1 C

Iahotoric. (II onI) T

Fabric Construction Vartest reported TI and CG cloth to be crepe weave (not momie) More data needed

Yarn Type Vartest reported CG to be ring-spun and TI to be open-end yarn More data needed

Thread Count 2% 4% 4% -11% between Significant difference

TI and CG, but not between CG and TI. may be

overlapping TI lot connected to RMC

difference

Fiber Content 4% 4% 6-12% No discernable differences

between lots and

laboratories. Differences

between CG and TI may be

connected to RMC

Yarn Number 2% 2% 12% No discernable differences

between lots and

laboratories. Differences

between CG and TI may be

connected to RMC

Fabric Weight Small 5% 2% 5% between lots

______________________ ______________ __________________ ________________

may be significant

Finish Not enough data Some reported Same finish on Finishes reported, but no

both connection to RIvIC

Water Retention Data here difficult to analyze because of differences in test More information needed

methods/results

Absorbency Large Large Not reported More information needed

Vertical Wicking Rate Not enough data Not enough data Not reported More information needed

Repellency Data indicates all samples studied absorb oil and water No differences noted

4-6

EE-RM-PET-100 COMMENT 88
4.3 Comparison of Cloth Characterization Test Results with R1'1C Test Results

Table 4.3 indicates some differences in cloth characteristics that may be linked to RMC

results. However, there are no clear connections. There is reasonable uniformity in characteristics

between TI lots reported here and these differences are within the same bounds as the differences

in RMC results. This suggests that a "standard" cloth should originate one manufacturer to limit the

variability of characteristics. The tests available for finish can be extensive. However, two simple

droplet tests for absorbency of water and oil can be used to detect the type of stain of water repellent

finish that could be inadvertently applied during production of this fabric.

4-7

EE-RM-PET-100 COMMENT 88
5. R1\'IC Correction Factor

As discussed in the preceding sections, the relationship that can be discerned between

measurable, specifiable properties of the cloth and the resulting moisture absorptionlretention

characteristics as measured by a standard RMC test is tenuous at best. The difficulty of relating

specifiable characteristics - fiber content, weight, etc. to RMC characteristics is compounded by the

wide tolerances that apply to the nominal specifications of textile products. The textile industry

requires wide tolerances to allow for the variability of cotton and synthetic fibers, as well as process

control variability. Based on discussions with textile industry marketing and manufacturing

managers, special manufacture to tighter specifications is probably not available; based on the

laboratory testing to date, tight specifications alone will not necessarily lead to a comparably

consistent RMC characteristic.

Based on the highly consistent extractor based RMC-g curves for TI lots 1, 2, and 3, it appeared

that a viable approach to minimize the effects of cloth variation on RMC would be to consistently

specify a single type of fabric that is produced frequently by one mill to a consistent set of

specifications. Riegel Permalux 50/50 Momie Weave (the cloth used for TI lots 1, 2, and 3) appears

to be a suitable choice, because this cloth is produced in high volume, has been produced to a

consistent specification for many years and is likely to continue to be produced on this basis for the

foreseeable future. Riegel produces the yarns from purchased fiber and weaves and finishes the cloth

material, so they have complete control over the process.

However, as discussed in the preceding sections, the extractor based RMC-g curves of

subsequent lots of the Riegel cloth (TI lots 4 and 5) were 5 to 8 percentage points higher than the

corresponding RMC-g curves for TI lots 1,2, and 3. To account for lot-to-lot variation, Robert Van

Buskirk of Lawrence Berkeley Laboratory (LBL) proposed a linear least squares fit based RMC

correction (Appendix C). The basic approach is to define standard RMC vs. g values for cold and

warm (60°F and 100°F) water and 4 minute and 15 minute spin times. The RMC values of TI lot

3 have been adopted as this standard. For other lots of test cloth, RMC-g values are absorbed in the

standard extractor. A linear least squares fit between the new cloth RMC and the "standard" cloth

RMC yields a linear relation between the RMC obtained with the new cloth and the RIVIC that would

have been expected with standard cloth. Figure 5-1 illustrates the basic concept.

5-1

EE-RM-PET-100 COMMENT 88
Standard Test

Cloth Basis Standard RMC for Clothes

Correction

Curve

RMCfor H

Standard Clothes

A New Lot of Extractor RMC Washer X with Test Cloth V5• g

New Test Cloth

Figure 5-1 RMC Correction to Determine the RMC that would have been

Measured with "Standard" Test Cloth

As described below, test results to date indicate that this procedure produces results that are

highly consistent.

The material below summarizes the proposed method to determine the correction factor curve

for a new lot of test cloth and the test data, to date, that shows that this procedure will yield

consistent RMC results for clothes washers.

5.1 Procedure to Calculate Correction Factor

The typical linear correction curve that is generated is shown in Figure 5-2. The simple

algebraic equation is

RMCCOI.rected= A + B*RM'measured

Where:

• RMCconected is the average RMC that would have been expected at each test condition for clothes

washer X if "standard" test cloth had been used for the Jl RtvIC test

• RMCmeasured is the RMC measured by the J 1 test procedure for clothes washer X with a lot of

non-standard test cloth for which a linear correction curve has been created.

5-2

EE-RM-PET-100 COMMENT 88
A and B are the coefficients (intercept and slope) that result in the least squares linear fit relating

the RMC values measured in the standard extractor for a particular lot of non-standard test cloth

and those that were measured with standard test cloth, at each water temperature, spin time, and

g test point

The procedure has four basic steps.

1. Establish the standard RMC vs. g values for cold and warm water and 4 minute and 15 minute

spin time.

2. For a new lot of test cloth, measure the RMC vs. g values for cold and warm water and 4 minute

and 15 minute spin time.

3. Linear least squares fit and root mean square (RMS) error check to generate the linear correction

curve.

4. Apply correction to Ji measurements of RMC with clothes washer.

5.1.1 Standard RMC vs. g Curve

The standard RMC vs. g values are summarized in the "standard cloth" column of Table 5-1.

They are the average of three measured RMC values at each spin time - water temperature - spin

g test point with test cloths from TI lot 3. They were measured in a Bock Model 215 extractor. For

this test procedure it was decided that the Bock Model 215 extractor would be the "standard".

5.1.2 Establish RMC vs. g Values for New Test Cloth

Using the standard Bock Model 215 extractor measure the RMC at the specified combinations

of spin time, water temperature and spin g in Table 5-1. Each of the RMC measurements should be

done three times, with the average used to determine the correction curve.

5.1.3 Least Squares Fit and RMS Error Verification

Using a spreadsheet or statistical calculator, calculate the linear least squares fit relating the pairs

of "standard" and "new cloth" RMC values at each of the spin time - water temperature - spin g test

points.

To quantify the uncertainty of the linear least squares fit a root mean square error analysis is

performed. The root mean square value of:

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EE-RM-PET-100 COMMENT 88
12

1=1

Should be less than 2-percent.

(RMCstandardRMq \2xs)hhi'2

orr_i)

10

The Root Mean Square (RMS) is a standard statistical quantity generated in least-squares

regression analysis. It is typically used to construct confidence interval estimates and to test

hypotheses about the derived model. The RMS quantifies the amount of variation (or uncertainty)

associated with estimating the standard RMC % from any corresponding RMC % value observed

with new cloth. Underlying theory and computational details are given in most applied statistics

texts.

Table 5-1: Standard RMC vs. g Values and Corresponding New Cloth RMC Values for Linear

Least Squares Fit

Sjiii Tinic Wii.r Ttmperauiie Sph g' RIC leaiirtd iii ihr Standaid Etraclnr

Staudard (loili ] Nes Cloth

4 mm. Cold 50 59.0% ___________________

200 43.1%

350 35.8%

_________________

____________________

Warm 50 55.7% ___________________

200 40.4%

350 33.1%

___________________

___________________

15 mm. Cold 50 52.8% ___________________

200 37.9%

350 30.6%

___________________

___________________

Warm 50 50.4% __________________

200 35.6%

350 29.6%

__________________

___________________

5.1.4 Apply to Clothes Washer Test Results

Once the linear correction curve has been generated for a new lot of test cloth, energy test cloths

and stuffers may be used to perform the Ji RMC test on any clothes washer to which the Ji test

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EE-RM-PET-100 COMMENT 88
procedure is applicable. The RMC measured with the new test cloth is corrected to the standard test

cloth RIvIC, either graphically using a plot of the linear correction curve, or arithmetically, using the

linear equation with the coefficients A and B that define the linear correction curve.

5.2 Test Data Confirming Correction Procedure

To evaluate the effectiveness of the correction procedure, results from extractor RMC-g tests

for TI lots 4 and 5 were used to generate the linear correction curves to TI lot 3. The resulting

coefficients for the linear correction equation RMCStd A + B*RJVIC measured are summarized in Table

5-2.

Table 5-2: Correction Coefficients

Tet (2Iolh Li A B

TI 4 -0.038 0.967

T15 -0.0319 0.9975

The linear correction curve and the individual extractor RMC data points for lots 4 and 5 are

plotted in Figures 5-2 and 5-3, respectively. The individual data points are the average of the 3 RMC

values measured for each combination of water temperature, spin time, and spin g. The detailed data

is shown in tabular form in Appendix D.

Correction Curve for Lot 4

65.00% -

60.00% -

55.00%

50.00% -

a

45.00% -

40.00% -

35.00% -

30.00% -

25.00% -

30.0 0%

- 0.9676 - 0.038

35,00% 40,00% 45.00% 50.00% 55.00% 60.00% 65.00%

Lot 4 RMC (1⁄4)

Figure 5-2: Linear Correction Curve for TI Lot 4

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EE-RM-PET-100 COMMENT 88
Correction Curve for Lot 5

65.00% -

60.00% --

55.00% -

50.00% - 0

45.00% -

40.00%

35.00% -

30.00% -

25.00% -

30. 0 0%

0.9975x-0.0319

35.00% 40.00% 45.00% 50.00% 55.00% 60.00% 65.00%

Lot 5 RMC (%)

Figure 5-3: Linear Correction Curve for TI Lot 5

The results of the extractor-based correction curve tests are shown in table 5-3 and 5-4. The

tables show the standard (Lot 3) measured value, the Lot 4 (or 5) measured value, and the corrected

value. All measured values are shown, however, the average of the three test values at each

condition are used for the least squares curve fit.

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EE-RM-PET-100 COMMENT 88