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NAT L INST. OF STAND & TECH

uiiQt. 55 ^ 6^3 81-2291 (HUD)

Performance Aspects of Water

Conservation Techniques for

Appliances

Charles C. Gordon

Robert L. Palla, Jr.

Center for Consumer Product Technology

National Engineering Laboratory

U.S. Department of Commerce

National Bureau of Standards

Washington, DC 20234

May 1981

Prepared for: -QC

100

.056

81-2291

1981

ffice of Policy Development and Research

epartment of Housing and Urban Development

ashington, DC 20910
1
NBSIR 81-2291 (HUD)

RATKMAL HUBEAD

or standards

LIBBART JUL 2 0 . 1981

PERFORMANCE ASPECTS OF WATER

CONSERVATION TECHNIQUES FOR

APPLIANCES

/ X

/ 4 21

Charles C. Gordon

Robert L. Palla, Jr.

Center for Consumer Product Technology

National Engineering Laboratory

U.S. Department of Commerce

National Bureau of Standards

Washington, DC 20234

May 1981

Prepared for: Office of Policy Development and Research

Department of Housing and Urban Development

Washington, DC 20910

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director
* *

,

W-V ' ... ;
PREFACE

This report is one of a group documenting National Bureau of Standards (NBS)

research and analysis efforts in developing water conservation test methods,

models for technical and economic analysis, and strategies for implementation

and acceptance of practices. This work is sponsored by the Department of

Housing and Urban Development, Office of Policy Development and Research,

Energy, Building Technology and Standards Division, under Interagency

Agreement H-48-78.

Table of Contents

Page

Abstract 1

1. Introduction 2

2. Performance Aspects of Water Conservation in Clothes Washers . . . . 2.1 Clothes Washer Water Conservation . . 2.2 Clothes Washer Performance

2.3 Soil Removal Test ....

2.3.1 Soiled Fabric

2.3.2 Test Load

2.3.3 Detergent ....

2.3.4 Test Conditions

2.3.5 Data Reduction ......

3. Laboratory Testing of Clothes Washers

3.1 Test Units

3.2 Tests Conducted ........

4. Test Results

4.1 Soil Removal Tests .....

4.2 Fill Height and Load Height Measurements in Tub

4.2.1 Fill Height

4.2.2 Load Height

4.3 Fill Level Recommendations . 1

5. Clothes Washer Summary 11 5.1 Water Conservation 11 5.2 Discharge Water 12

6. Performance Aspects of Water Conservation in Dishwashers 12

6.1 Typical Dishwashers 12

6.2 Dishwasher Water Conservation 12

6.3 Dishwasher Performance 13

6.3.1 Dishwasher Performance Test 13

6.3.2 An Alternate Approach for Evaluating Dishwasher Soil

Removal Characteristics . . 13

7. Laboratory Testing of Dishwashers 14

7.1 Test Units 14

7.2 Tests and Results 14

7.2.1 Soil Removal Breakdown and the Effect of

Eliminating a Rinse 14

7.2.2 Effect of Reducing Fill Volume 15

8. Dishwasher Summary 17

8.1 Water Conservation 17

8.2 Discharge Water 17

9. Conclusions 17

10. References 19

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List of Tables

Page

Table 1 - Characteristics of Clothes Washers Tested 20

Table 2 - Performance-Related Parameters 21 Table 3 - Water Level - Fill Level Relationships 22

Table 4 - Fill Heights and Test Load Heights 23

Table 5 - Dishwasher Cycle Phasing and Water Consumption 24

Table 6 - Percentage of Dishware Rewashed 25

List of Figures

Figure 1 - Average Soil Removal Versus Fill Level --7 Pound Load 26

Figure 2 - Soil Removal Variance Versus Fill Level --7 Pound Load .... 27

Figure 3 - Average Soil Removal Versus Fill Level —CW1 28

Figure 4 - Soil Removal Variance Versus Fill Level --CW1 and

9 Pound Loads 29

Figure 5 - Soil Removal Per Subcycle--All Units at Full Fill 30

Figure 6 - Soil Removal Per Subcycle--Uni t A; Full, 3/4, and 1/2 Fill . . 31 Figure 7 - Soil Removal Per Subcycle--Unit B; Full, 3/4, and 1/2 Fill . . 32

Figure 8 - Soil Removal Per Subcycl e--Uni t C; Full, 3/4, and 1/2 Fill . . 33

Figure 9 - Soil Removal Per Subcycle--Unit D; Full, 3/4, and 1/2 Fill . . 34
Abstract

The performance of household clothes washers and dishwashers is evaluated

assuming various water conservation methods. For clothes washers the effect of

fill level setting on soil removal is presented. A guideline for setting fill

level is suggested. For dishwashers the soil removal capabilities are evaluated

at reduced fill volumes. An analysis of the percentage of soil removed for each

wash/rinse subcycle shows the relative quantities of soil in the discharge for

each subcycle.

1
1 . Introduction

A prior study [l]*of various water conservation techniques for appliances

was conducted by the Center for Consumer Product Technology (CCPT) at the

National Bureau of Standards (NBS). That study considered only the potential

for reducing water consumption and did not address how the water reduction

affected performance of the appliance. The performance of the appliance is

closely related to the amount of water consumed in the operation. Although

water savings can be achieved through various water conservation strategies, at

seme level the reductions in water consumption will be accompanied by a

degradation in appliance performance. Decreases in appliance water usage beyond

that point may result in greater overall water consumption due to consumer

double-cycling of appliances, and can result in increased water usage.

The objective of the present investigation was to address the performance

limitations of several specific water conservation techniques identified in the

prior study. For clothes washers, the effect of fill level setting and load

size on soil removal was addressed; based on that work, a method for adjusting

fill level for optimum water savings was recommended. For dishwashers, the

effects on performance of reduction in water volume on food removal from soiled

dishware was investigated. In conducting the evaluation, the percentage of soil

removed in each dishwasher wash/rinse subcycle was determined. The extent of

degradation of the soil removed also served to give an indication of the

relative effectiveness of each subcycle and to show that discharge water from

selected cycles could be used in recycling systems.

2. Performance Aspects of Water Conservation in Clothes Washers

2.1 Clothes Washer Water Conservation

Results of the previous water conservation study [l] indicated that clothes

washer water consumption may be reduced by several means, for example, use of

front loading machines and use of suds-saver devices. In addition to these and

other techniques which are built-in and therefore practicable only at the time

of appliance purchase, more effective use of existing fill level controls by

consumers was identified as a powerful water conservation technique. It was

estimated, that through proper use of the level control, as much as 25 gallons

per complete cycle might be saved in those cases where minimum fill could be

used instead of maximum fill. More importantly though, if fill level could be

set to match the real water requirement for each different load size,

significant water savings should be realized by consumers. This would be

especially important during water shortages.

Either by appropriate recommendations to consumers on fill level settings

or by automatic level setting controls important savings could be realized;

however, since water usage is closely tied to washer performance, such

recommendations or controls must be based on consideration of performance at

reduced fill levels. They must also be consistent with instructions provided to

the consumer by the appliance manufacturer. The thrust of this current effort

in the area of clothes washer performance was therefore to determine the

*Numbers in brackets indicate references in Section 10.

2
relationship between water usage and washing performance. This relationship

provides the basis for fill level recommendations for water conservation—the

final objective of the clothes washer portion of this study.

2.2 Clothes Washer Performance

Clothes washer performance is a multifaceted appliance characteristic. As

such, overall performance cannot be given by any single factor. Many factors,

including soil removal, rinsing effectiveness, and water removal, must be

considered in a complete performance evaluation.

The most comprehensive set of criteria for evaluating clothes washer

performance is a voluntary industry standard prepared by the Association of Home

Appliance Manufacturers (AHAM) as AHAM Standard HLW-1, "Performance Evaluation

Procedure for Household Washers," and subsequently adopted as a National

Standard by the American National Standards Institute (ANSI) as ANSI 224-1-1971.

This standard consists of seven separate test procedures, each covering a

different aspect of clothes washer performance. These are:

o soil removal — removal of soil from fabrics

o sand removal — removal of insoluble and heavier-than-water

soils from clothes and machine

o whiteness retention — retaining whiteness in unsoiled areas while removing soil from soiled areas

o rinsing effectiveness — rinsing laundering products

from clothes

o water removal — extraction of water from wash board

o gentleness of action -- effect of washing on fabric

o tangle free action tangling of clothes among themselves

and with parts of machine

- Although developed by industry representatives, not all of the AHAM clothes

washer test procedures are not currently in widespread use by manufacturers; in

many cases various tests have been modified or have been replaced by more

sophisticated tests to suit particular needs. Also, manufacturers have

developed their own test procedures to evaluate additional performance factors,

such as wear and abrasion. Nevertheless, the AHAM test procedures still fulfill

their original purpose, that is, to obtain a measure of the performance of a

given machine make and model under a given set of conditions.

Within the context of this study, evaluation of all performance factors as functions of water usage was not feasible. The time and equipment constraints, as well as the subjectivity of many of the test procedures precluded such an

approach. Instead, activity was limited to evaluating the primary performance

characteristic of the clothes washer, namely soil removal . Unlike many of the

other performance tests, the soil removal test is objective in nature and can be

carried out routinely.

3
2.3

Soil Removal Test

In the AHAM test, the soil removal characteristics of a clothes washer are determined through measurements of the optical reflectance of standard soiled

fabric swatches made before and after washing. Materials used in the test

procedure include standard soiled fabric, standard test loads, and standard

detergent. Test conditions and data reduction formulas are specified in the

standard (HLW-l). Unfortunately, the AHAM standard does not indicate how the

Soil Removal Index (SRI), determined in the test, translates to performance,

that is, excellent, good, or poor performance are not defined in terms of the

SRI. Hence, the AHAM Soil Removal test must be regarded as a surrogate measure

of performance, particularly for changes in performance.

2.3*1 Soiled Fabric

The standard soiled fabric is a white cotton cloth that has been treated

with an artificial soil to simulate body oils and other soils; the resulting

fabric is dark grey in color. The soiled fabric used in this study was obtained

commercially from an AHAM supplier in the form of a nominal 18 inch roll. The

fabric was certified to have a reflectance of 84.6 percent prior to soiling and

24.6 percent after soiling, as measured by a Hunter Reflectometer.

In accordance with the AHAM test procedure, the soiled fabric was cut into

swatches measuring approximately 14 by 11 cm (5*5 by 4*3 in.). The swatches

were numbered and then randomized to reduce any effects of non-uniformity

throu^iout the bolt of fabric. The initial reflectance (before washing) of each

swatch R

s was measured and the swatches were then pinned to the test load. A

separate group of 20 swatches was used to normalize the soiled fabric by washing

them in a Terg-O-Tometer*— a standardized washing device specified by the test

procedure.

2.3*2 Test Load

Two types of test loads may be used in the AHAM test procedures: the

preferred AHAM Standard Mixed Cotton Test Load, consisting of various articles

of clothing and household linens, or the AHAM Stuffer Load, consisting of 61 by

91 cm (24 by 36 in.) cotton cloth double hemmed on all edges. The latter test

load was used in this study to facilitate testing.

2.3.3

Detergent

The detergent used in all tests was the AHAM Standard Low Sudsing Detergent

No. 2A. A detergent concentration of 6.00 + 0.40 grams per gpllon of wash water

was maintained at all fill levels.

2.3.4

Test Conditions

After affixing the soil swatches to the test load, the load was placed in

the washing machine, detergent was added, and the wash cycle initiated. Wash

(agitation) time used was 15 minutes or the maximum time provided by the

"Terg-O-Tometer" is a standardized device manufactured solely by United

States Testing Company, Inc. Its use is required by ANSI Z224. 1-1971.

4
machine, whichever was shorter . For all tests, wash and rinse water

temperatures were controlled at 60 + 1 C (140 + 2 P) and 38 + 3 C (100 + 5 F)

respectively. Water hardness was maintained hetween 0-1 grains through use of a

water softener.

2.3*5 Data Reduction

Upon completion of the cycle, the soil swatches were detached from the test

load and air-dried. The final reflectance value, F^, was then measured. The

initial and final reflectances were converted to percent soil removed using the

Kubelka-Marik: equations. These are:

(la)

and:

n\ - /a

CD - 'S I S IS] w x 100 (ib)

where:

c

1

</> (Du

K = coefficient of reflectivity

S = coefficient of ligjht scatter

R = observed reflectance, soiled and

SR = percent soil removal.

The subscripts in Equation (lb) denote the condition of the test swatches,

that is: s = soiled fabric

w = washed fabric

u = unsoiled fabric

A value of 0.0089 is assumed for K . This value is based on

S

numerous measurements made by AHAM and confirmed by the vendor of the soiled

fabric.

In the test procedures, statistical measures such as standard deviation and

variance of the soil removal values are calculated for both soil swatches washed

in the machine under test and swatches washed in the Terg-O-Tometer. The soil

removal values for the appliance are then normalized with respect to those for

the Terg-O-Tometer to yield a Soil Removal Index (SRI). Normalization was not

necessary in this study because all soiled fabric was from the same lot (bolt)

and because changes in soil removal rather than absolute measurement of soil

removal were of primary interest here.

5
3* Laboratory Testing

The soil removal characteristics of several different model clothes washers

were evaluated at various fill levels. The objective of these tests was to

investigate the relationship between fill level and performance; specifically,

soil removal. Recommendations on fill level settings for water conserving

operation were later made based on these test results.

3.1 Test Units

Five different clothes washers were selected for testing, three 1973-1974

and two 1978 models. All machines were large capacity, fully-automatic , toploading units equipped with adjustable fill level controls. These machines

represented a variety of different agitator/tub designs, but all machines except

one operated in a similar mode, that is, wash, drain and spin with a spray rinse or rinses, deep rinse, and a final drain and spin. The one exception operated

in the same mode but had an additional spray rinse during the final spin. Some

characteristics of the test machines are presented in Table 1.

3.2 Tests Conducted

The soil removal characteristics of all five machines were evaluated using

a 7 pound AHAM Stuffer Load and fill levels ranging from minimum to maximum. A

7 pound load was used because studies have shown that nearly one-third of all

wash loads weigh between 6 and 8 pounds [2].

In a second group of tests, one of the five machines was tested at various

fill levels using both 5 and 9 pound test loads. While it was recogiized that

these load sizes did not represent the extremes it was necessary to limit the

range in order to ensure that the loads could be washed at both underfill and

overfill conditions without having to modify the fill level control on the

machine. It was felt that these fill levels would still provide an adequate

basis for making fill level recommendations.

Upon determining the "optimum" water conserving fill levels, that is, the

points at which a further reduction in fill level results in a perceptible

degradation in performance, the relationship between fill height and clothes

load hei^it at these points was investigated. This relationship is discussed

in Section 4.2.

4* Test Results

4*1 Soil Removal Tests

The results of all soil removal tests with the 7 pound load are presented

in Figure 1. Each data point in Figure 1 represents the average of the average

soil removal for the 15 standard soil swatches (tests at each fill level were

repeated twice) . It can be noted in Figure 1 that not all machines exhibit the same performance trends with differing water levels. For example, the

performance of CW1 drops off continuously as water level is decreased, while the

6
performance of CW2 and CW4 improves before dropping off (CW4 is the 1978 version

of CW2 and is virtually identical in appearance) . Also, the difference in soil

removal from machine to machine is as large as the change in soil removal when

water level is varied.

Because the AHAM test procedure does not relate soil removal values to

washer performance, it does not provide a means of rating performance, that is,

excellent, good, poor. Since the value of soil removal that represents

acceptable performance is not defined under reference standards, it can only be

stated that unacceptable performance occurs somewhere below the curve for

machine CW4 shown in Figure 1. In reality however, when fill level is reduced,

perceptable degradation in performance occurs before the average soil removal

value drops below this level. The performance problem manifests itself in the

laboratory as an increase in the spread of soil removal values measured for the

15 soil swatches used in each test. That is, soil removal from some swatches is

significantly greater than average at low fill levels, while soil removal from

other swatches is far less. In the home, some items of clothing would still

appear soiled after washing.

The mechanics of the soil removal problem at reduced fill levels can be

summarized as follows: when the fill level is reduced, the movement or circulation of the test load and swatches within the washer tub is inhibited; as a result, some swatches stay in the area of the agitator vanes and are washed

well, while other swatches remain in relatively stagnant areas of the tub and

receive little washing. The soil swatches which receive little washing,

typically two of the 15 swatches, in tests conducted in this study, exhibit very

low soil removal and are the main cause of low values of average soil removal

for the run.

A plot of soil removal variance for all tests with the 7 pound load is

presented in Figure 2. Here the data points represent the average of the

variances for each of three test runs. It can be noted from Figure 2 that the

soil removal variance for all machines tested behaves the same as fill level is

reduced. In fact, three of the five machines have nearly the same soil removal

variance for wash water use above 16.5 gallons, and the variance for the

machines increases significantly as water use is reduced below this point.

Soil removal results for CW1 are shown in Figure 3 for tests with the 5, 7,

and 9 pound test loads. Machine CW1 was selected for these tests because it was

equipped with a 19 position fill level control and had the widest range of water

usage of all machines tested. As Figure 3 illustrates, the trend toward lower

soil removal values with decreased water usage holds for all load sizes. As

before however, percent soil removal by itself does not lend insist into the

circulation problem which develops as fill level is reduced—but the soil

removal variance does provide correlation.

Figure 3 shows the increase in soil removal variance for all three loads as fill level is reduced. This increase is attributed to a direct result of a

decrease in load circulation in the wash tub as fill level is reduced. The

points at which the variance begins to increase significantly can be interpreted

7
as the optimum fill level for water conservation. This interpretation has been

confirmed by several clothes washer manufacturers. It is important to realize

however, that the optimum fill level for water conservation may not be the best

fill level with regard to other performance measures, for example clothing

wrinkling and fabric wear. These other aspects of performance would need to be

dealt with separately and are beyond the scope of this report.

The optimum fill levels for the 7 and 9 pound loads for machine CW1 are well defined—16.5 and 21.0 gallons of wash water, respectively as shown in

Figure 5* The increase in variance for the 5 pound load is not as distinct, but

begins to become significant somewhere between 10.5 and 15.5 gallons. The

optimum fill level for this load size is therefore estimated as 12.0 gallons,

the mean.

Since only one machine, CW1, was evaluated with test loads other than the 7

pound load, some relationship between load size and optimum water usage was desired so that the results for the other machines could be extrapolated to

different load sizes. Ratios of parameters believed to be related to the

washing process were calculated for this purpose. These parameters included

optimum water usage, WU; test load weight, WTM-; test load volume, V^.; volume of

free water in the inner wash tub, V^-m ; and total volume in the innSr tub, V-^.

Values of these parameters and several groupings of the parameters are given m

Table 2.

It can be seen from Table 2 that ratios of wash water usage to test load

weight or volume are approximately constant at the optimum fill level for each

load size and these ratios can be used to estimate optimum water usage, e.g.

,

for OH the optimum fill level is that for which WU/V^-r = 13* Since the optimum

fill level for three of the four remaining machines was also about 16.5 gallons

for a 7 pound test load, the water to test load volume for these machines is

also about 13 (the proportionality constant 0.18 gallons per pound of test load

"is used to determine the volume of water displaced by the test load). Hence,

the optimum water usage for all machines is approximately the same—12.0, 16.5,

and 21.0 gallons of wash water for the 5, 7, and 9 pound loads, respectively.

It is interesting to note that for a 12 pound test load, the optimum water

usage criterion W/Y^j = 13 would dictate a wash water volume of 28 gallons—

a

volume in excess of xne tub capacity. Consequently, water usage for this load

size will be less than optimum and some non-uniformity in soil removal would be

observed. This prediction is not surprising since a firmly packed 12 pound test

load would fill the tub to near full capacity, thus inhibiting free circulation.

4.2 Fill Height and Load Height Measurements in Tub

The relationship between the height of the test load in the wash tub and

the height of the water at optimum fill was investigated to provide a basis for

fill level recommendations for water conservation. As a first step, the height

of the water in the tub was determined as a function of wash water usage. From

these relationships fill height was calculated for each of the optimum fill

8
levels. The heights of the 5, 7, and 9 pound test loads in the tub were then

measured under different methods of loading and compared to the fill heights.

4*2.1 Fill Height

Basically, a clothes washer consists of two concentric tubs—the inner

perforated tub which holds the clothing and the outer solid tub which holds the

water. Water in the disc-shaped void between the bottoms of the two tubs, and

in the annular void between the sides of the two tubs does not take an active

part in the washing process but nevertheless adds to water consumption.

As one would expect from the cylindrical shape of the outer tub, fill

height as measured from the floor of the inner tub is essentially linear and is

given by:

Fill Height = m (water usage) + b

The slope, m, of the straight line is directly related to the diameter of the

outer tub and may be interpreted as the change in water level per gallon of

water added; the intercept, b, is a depth measurement that is proportional to

the volume of water in the disc-shaped void between the bottoms of the two tubs.

Values of m and b for the five machines tested are given in Table 3* It can be

noted from these values that each inch in fill height is roughly equivalent to

two gallons of water. Also, for a given amount of water the fill level in CW2

and CW4 will be higher than in the other machines due to a smaller outer tub

diameter (larger m) and reduced clearance between the bottoms of the two tubs

(larger b) or conversely, for a given fill height (depth), the volume of water

is reduced. As a result, these machines have a lower per cycle water

consumption.

Based on the water usage/fill height relationships, the fill heights at

optimum water usage can be computed. Fill heists for the machines tested are

presented in Table 4 for the case in which the tub is filled with the clothes

load already in the tub (as recommended in laundering guides accompanying new

machines) and the case in which the tub is filled and the load is added later.

The change in water level due to adding the load is only about 1 inch.

4*2.2 Load Height

The height to which a dry load of clothes fills the clothes washer tub is,

for practical purposes, the only means of gauging the fill level needed for

washing. By necessity then, any recommendations for setting the fill level must

relate in some way to load height in 'the tub. Unfortunately, load height can be

highly variable. Fabric types, wash load makeup, machine tub/agitator design,

and loading technique all affect the load height. A cursory analysis of clothes

load hei^it in the tub was therefore undertaken to provide a basis for relating

optimum fill level to load height.

The approach taken here was to measure the heights of the 5, 7, and 9 pound

test loads in the tubs of the test machines under different loading practices,

9
and then compare these values to the optimum fill heights. For these

measurements it was recognized that the AHAM test loads do not represent the

wide variety of fabric types and wash load makeups encountered in actual use;

however, it was believed that the stuffer test load would reasonably indicate

the relationship between fill level and load size.

The heights of the test loads in each machine were measured for two packing

techniques. First, the load was lightly placed in the tub uniformly about the

agitator in accordance with the AHAM method of loading, the result being a

loosely packed load. After taking the height measurement the load was then

firmly pressed down, eliminating much of the space between clothes and a final

height measurement was made. Measured load heights are presented in Table 4 for

loosely and firmly packed loads. For the sample test load used, the difference

in load height between the loosely and firmly packed test loads was 4 to 5

inches

.

4 • 3 Fill Level Recommendations

Comparison of the optimum fill heights to the test load heights, Figure 4,

indicates that for the 7 and 9 pound loads, the water-conserving fill height

occurs about midway between the loosely packed and firmly packed test load

heights. For the 5 pound load the optimum fill height is closer to the load

height when the load is firmly packed. In all but one case the optimum fill

height is somewhere between the loosely packed and firmly packed load. Hence, a

general guideline in setting the fill level might be: load the machine, pack

the clothes moderately, and fill the machine to the height of the clothes load.

The fill height should be referenced to some fixed point, perhaps a mark or scale on the agitator or tub, since the clothes load often tends to float during

the fill.

The instructions on setting fill level that are provided new clothes washer

“ owners by manufacturers are in good agreement with the fill level guideline

identified in this study. Manufacturers generally recommend two criteria for

setting fill level: l) use enough water so that clothes circulate and turn over

freely in the tub, and 2) use a fill level proportional to the amount (height)

of clothes in the tub; as a specific example the following guideline is provided

for one machine with a three position fill level control:

Whether the first criterion, based on circulation, provides a good fill

level setting depends on how "free circulation" is interpreted. Discussions

with several manufacturers indicate that the number of "turnovers" (an

observable measure of circulation) with a given load varies from one model

machine to another, and with the same machine varies with both load size and

fill level setting. The number of turnovers is usually about 10 to 15 in a 10

minute washing period, but can be as high as 30 and as low as 2 with the machine

Load Size Setting Amount of Clothes in Washer

Small

Medium

Largs

Less than 1/2 full

Between 1/2 - 2/3 full

Over 2/3 full

10
still giving satisfactory performance. Obviously, then, the first criterion is

by no means definitive. The second criterion agrees more closely with that

noted in this study, that is, the fill level should be proportional to the fill

hei^it.

It should be pointed out here that manufacturers include additional

recommendations pertaining to fill levels when washing permanent press and

delicate fabrics. Typically the recommendations are for the use of higher fill

level settings for these loads. These recommendations are based on consideration of wrinkling and pulling of seams.

5» Clothes Washer Summary

5.1 Water Conservation

The effect of fill level setting on the performance of five top-loading

clothes washers was determined using standard test procedures. The soil removal

capabilities of all machines were evaluated using a 7 pound AHAM Stuffer Load

and fill levels ranging from minimum to maximum. One of the machines was then

tested at various fill levels using both 5 and 9 pound test loads.

Results of the soil removal tests indicated that the variance of the soil

removal from each of 15 soiled swatches used in the tests was a better indicator

of performance degradation than the average of the soil removal. As fill level

was reduced, the point at which soil removal variance increased significantly

was well defined. The fill level at this point was considered to be the

"optimum" water conserving level, since any further reduction in fill would

result in a greater non-uniformity in washing. Optimum fill levels were

identified as those providing a wash water usage of 12.0, 16.5, and 21.0 gallons

for the 5, 7, and 9 pound test loads.

It was noted that one inch of water in the washer tub corresponds to

approximately 2 gallons of water. The ability to adjust fill level to within an

inch or so is therefore highly desirable for water conservation purposes.

Machines which provide for "finer" fill level adjustments should be promoted

over those having only course adjustments.

The relationship between the height of the test load in the wash tub and

the height of the water at optimum fill was then investigated. It was found

that the optimum fill height occurs somewhere between the load hei^it when the

load is loosely packed and the load height when it is firmly packed. The fill

setting guideline suggested from this work is: load the machine, pack the

clothes moderately, and fill the machine to the height of the clothes load using

a fixed point on the agitator or tub as a reference point. This fill

recommendation is in agreement with instructions provided to consumers by

clothes washer manufacturers.

11
5.2 Discharge Water

Total water consumption for a typical large capacity top-loading clothes

washer is about 50 gallons for a normal cycle at maximum fill level—25 gallons

each for the wash and deep rinse subcycles, and 5 gallons for the spray rinse.

Clothes washer discharge water therefore represents a significant source of

water for recycling systems. Reuse systems have been considered in detail by

Bailey et al. [5] and have been demonstrated in several field installations [4,

5]. Therefore, the reuse of clothes washer discharge water has not been

considered in this study.

6 . Performance Aspects of Water Conservation in Dishwashers

6.1 Typical Dishwashers

A full line of dishwashers with varieties of control options are currently

on the market; these range from the "basic model” to the "top of the line".

Most dishwashers are equipped with several wash cycles and special features,

depending on the particular model. Typical wash cycles include super or heavysoil wash, pots and pans, normal wash, short or light wash, rinse and hold, and

others. The consumption of water for the various cycles ranges from 2 to 4

gallons for the rinse and hold cycle to over 16 gallons for a heavy-soil cycle.

The typical "normal cycle" sequence consists of a wash, a rinse, a wash,

and two or three rinses with a water change occurring between each of these

subcycles. The phasing and number of these wash and rinse subcycles is not

uniform among dishwashers even on the "normal cycle". Also, the amount of water

used in a particular machine may not be uniform for each wash or rinse subcycle.

Cycle phasing and water consumption information for several dishwashers, Table

5, illustrates this variation among models.

6.2 Dishwasher Water Conservation

As identified in the prior CCPT water conservation study [l], water savings

of about 2 to 5 gallons are possible by using the short cycle when the dishes

are lightly soiled. Such a cycle is equivalent to the "normal" cycle with one or two washes or rinses eliminated. Another technique identified, although not

easily implemented by consumers, was reduction of the volume of water used per

dishwasher fill or subcycle. With either of these two water conservation

strategies however, adequate washing performance is necessary in order for any

savings to be realized. Prior to making recommendations to consumers and

planners regarding these water conservation options—an eventual goal of the HUD

program—a study of the performance aspects of these options was therefore

deemed necessary. In view of a lack of quantitative performance data on which

to evaluate the feasibility of the water conservation options, such a study was

undertaken by CCPT. The objectives of the dishwasher study were three: 1)

evaluate the soil removal characteristics of the dishwashers under design

conditions, 2) determine the effect on performance of eliminating a final rinse,

and 3) determine the effect of reducing the volume of water used per fill or subcycle

.

12
6.3 Dishwasher Performance

Unlike clothes washers, the performance requirements for dishwashers are quite simple-—to remove soil from dishware and dry the dishware without

spotting. As such, from an aesthetic point of view, soil removal is the most

important single aspect of dishwasher performance. Bacteriological

considerations are also important hut are beyond the scope of this study.

6.3.1 Dishwasher Performance Test

Most manufacturers/distributors currently use the Association of Home

Appliance Manufacturers (AHAM) standard test procedure DW-1 [7] to determine the

performance (washing index, Wl) of their products. Some companies however, use

a yet more rigid test procedure than the DW-1, in an attempt to assure a more

satisfactory product for the consumer. For the determining effects on performance of dishwashers with water conservation techniques the soiling

portion of the AHAM test was used.

The DW-1 procedure for determining the washing performance of a dishwasher

consists of washing a standard set of dishware place settings that have been

soiled with specified foods that are difficult to remove. The foods are prepared and applied in a prescribed manner according to a timed procedure.

After application, the soiled dishware is allowed to air dry. Then the dishware

is washed using a standard AHAM detergent and a wetting agent to reduce

spotting. The evaluation of the washing performance (washing index) is based on visual inspection of the dishware by a team of four trained judges who rate the

cleanliness on the basis of the number and size of spots of food soil remaining

on the dishware. A formula is used to reduce the data from each judge to a

washing index, WI, representing the percentage cleanliness of the wash dishes.

The four judges' results are averaged to obtain the final WI value.

The main disadvantage with this procedure for rating dishwasher performance

is that it is a subjective method based on the visual observations of four

judges. Therefore, it can produce a significant spread in percentage

cleanliness ratings among the judges. An additional drawback is simply the

effort required to judge the washed dishware. In view of these drawbacks an alternate approach was taken for evaluating dishwasher soil removal

characteristics

.

6.3*2 An Alternate Approach for Evaluating Dishwasher

Soil Removal Characteristics

One objective of the present study was to determine the relative percentage

of soil removed in each subcycle and evaluate the effect on performance when a

rinse is eliminated and/or the quantity of water for each fill is reduced. One

means of obtaining such information for a given machine would be to conduct the

AHAM performance test on the machine for a complete operation cycle and to then

report the test for truncated cycles. In this way, the significance of each

additional subcycle is represented by the observed degradation in performance.

Due to manpower requirements and subjectiveness of the AHAM test however, a

13
measurement of soil removal in each subcycle was used. A breakdown of soil

removal was determined by using the standard AHAM method for applying soil to

the test dishware, but instead of judging the dishware after washing, the

discharge water from each subcycle was filtered, and the residue wei^ied. This

gave a measure of the undissolved solids removed in each subcycle. The actual

procedure used was as follows: For each subcycle, a one liter sample of

discharge water was collected. To remove the soil particles each sample was

then passeg through a [laboratory type paper] filter that had been dried in an oven at 40 C, weighed, and maintained in a desiccator before use. The soiled

filter was dried and then reweighed to determine the wei^it of the soil removed

per liter of discharged water.

The filtration technique yields a relative measure of soil removal, that

is, soil removal for one subcycle relative to another may be obtained. This

data, presented in Figures 5-9, is useful for determining the number of gallons

of water from the subcycles that could be a potential source for grey water

systems. However, since the amount of soil applied to the dishes or still

remaining on the dishwasher cabinet or racks is not known, there is no simple

way to determine the amount of soil still remaining on the dishware. As a

result, this technique does not lead itself to the quantitative assessment of

dishwasher performance.

7- Laboratory Testing of Dishwashers

7.1 Test Units

A total of 4 dishwashers from different manufacturers were tested using the

"normal cycle" in each case. Some characteristics of these units are presented

in Table 5- Test instrumentation and procedure were according to the Federal.

Register "Uniform Test Method for Measuring the Energy Consumption of

Dishwashers" [6]. Energy consumption measurements were not conducted as part of

this study, but are reported in References [9-10].

7*2 Tests and Results

7.2.1 Soil Removal Breakdown and the Effect of Eliminating a Rinse

An analysis of the water discharged by dishwashers was conducted to

determine (lj the percentage volume of the food from soiled dishware that is

removed by each water change, and how these percentages are distributed in a

"normal cycle" for several typical dishwashers, and (2) what portion of the

discharge water can be considered for use in a grey water recycling system.

(The water discharged by a dishwasher into the household sewer system is

referred to as "grey" water.) Analyses of the biological, chemical, corrosive,

odor, storage, and distribution problems related to the applications of grey

water recycling system are regarded as separate tasks and ones which may need to

be performed in the future.

14
The soil removal for each of the four test dishwashers was determined using

the procedure described in Section 6.3.2. The "normal cycle" was used in all

tests. Four tests were conducted according to the procedure on Unit A. On the

dishwashers Units B thru D, three tests each were conducted. The results for

each machine were then averaged. The average percentage soil removed for each

wash or rinse is plotted in bar graph format in Figure 5 for each dishwasher.

Examination of the bar graph data in Figure 5 indicates that the majority

of all soil removed is removed in the first subcycle; also, the soil removed by

the last two rinses of Unit C and last three rinses of Units A, B, and D is

marginal—approximately 5 to 6$ for Unit B, and 2 to ^ for Units A, C and D. A

wash and two rinses constitute the last three water use functions designed in

Unit C, while the last three water changes in Units A, B, and D perform only

rinse functions.

It can also be noted from the bar graphs that soil removal during the final

rinse is marginal. It would thus appear that the last one or possibly two

rinses mi^ht be eliminated without sacrificing significant performance. Yet,

while 1 or 2 percent soil removal does not amount to a large volume of soil, it

can reduce performance and user acceptance if left on dishware in the form of

specks and spots of food stuffs. For example, in tests previously conducted by

NBS using the complete AHAM test procedure, the last rinse of Unit D was

eliminated. Although the volume of soil normally removed in this rinse is

minimal, the washing index of the machine, as determined by a panel of judges,

was found to be 5 percentage points less than for the full cycle.

Analysis of the data in Figure 5 for the limited testing of these four

dishwashers indicates that the water from the last three water changes could be

considered a potential source for a stored "grey" water sweep system.

7.2.2 Effect of Reducing Fill Volume

A series of tests were conducted to determine if the household dishwasher

can be operated on a reduced amount of water per fill without degradation of

washing performance. The premise is that more water is used per fill than is

required and a reduction of this is a potential source of water saving.

Each of four dishwashers was loaded with twelve soiled place settings of

AHAM specified dishes except for a serving platter and serving fork. The time

for each fill for each dishwasher was determined and then washing performance

tests were conducted with the fill time reduced first by 25$ (3/4 volume per

fill) and then by 50$. Tests of 5$ and 10$ less water per fill were not

conducted since this is in the range of variation due to the solenoid-operated

fill valves. An external switch was used to interrupt power to the fill

solenoid to obtain either 3/4 (25$ water reduction) or l/2 volume of water per

fill (50$ water reduction) depending upon which test was being conducted.

Reductions in fill volume are directly proportional to reductions in fill time

since the dishwashers fill at a constant rate [ 1 ]. No other electrical or time

changes were made in the "normal cycle" as controlled by the timer.

15
Bar graphs for each of the four machines for full, 3/4 and l/2 water volume

for each fill are presented as Figures 6 through 9* Even though there was no absolute measure of the soil applied to the dishes or removed during the cycle,

examination of the graphs indicates that less soil was removed in the early wash

and rinse subcycles when washing with reduced fill. As a result, with reduced

fill, a largpr percentage of the soil was removed in the later subcycles. In

some cases, such as with Unit D at 1/2 fill (Figure 9), substantial amount of

soil were still being removed in the last rinses.

A visual inspection of the inside of the dishwasher and all dishes and

flatware was made after washing a dishwasher load with reduced water volume per

fill to determine the degree of performance degradation and whether rewashing

was necessary. The criterion for determining whether a piece was to be rewashed

was the subjective judgment as to whether or not a user would place the piece

with the clean dishware supply. Test results are presented in Table 6.

The data in Table 6 shows that for a volume per fill of 3/4 for a single

test on each of four dishwashers, 25 to 73$ of the washed pieces needed

rewashing and with only a l/2 volume per fill, the percentage of rewashing

required was 43 to 85$. Typically the unsatisfactory performance was due to

undissolved detergent on the dishware, soiling food not removed from the

original soiled dish or flatware, and food being removed from one piece and

deposited on another piece not soiled with that material. In addition the

inside of all four of the test dishwashers contained the soiling food and

undissolved detergent on the dish racks and tub walls after both a 3/4 fill and

a 1/2 fill cycle. This required a clean-up cycle to be run after each test

before further testing could be conducted.

The largest number of pieces to be rewashed had been located in the upper

racks of all dishwashers. This is due to the dishwasher pump not supplying

water in sufficient quantity and at the required pressure to the upper sprayer,

spray arm, or tower for the upper rack — a result of lack of water at the pump

inlet. Both the lower and upper water rotating spray arms, towers, etc., depend

upon water pressure from the pump to fimetion properly.

The effect of reducing fill on the operation of the water distribution

system was visually observed by replacing the door on one of these test

dishwashers with a clear plastic door. With the normal volume of water per

fill, the lower spray arm rotated at approximatley 52 revolutions per minute,

but when the fill was only 1/2, the spray arm rotation dropped to approximately

31 revolutions per minute. In addition, with low fill the streams were weak

from the lower spray arm from the upper distribution system functioned

erratically or at times failed completely.

As a result of these tests, it is concluded that reducing fill volume is

not a satisfactory method for obtaining a water savings in a dishwasher without

engineering modifications to the water pump and spray system. Such

modifications are discussed in Reference [ 1 ].

16
8. Dishwasher Summary

8.1 Water Conservation

The performance (washing index) of all dishwashers, as currently designed,

would likely degrade upon elimination of a rinse in the "normal wash" cycle.

Whether performance would be acceptable would depend upon the machine design and

degree of soiling. Some machines can afford the slight reduction in performance

which accompanies the rinse elimination, others simply cannot. The users must

determine themselves, from trial and error, which loads can be washed with a

short cycle. Consumer use of these cycles can result in water savings of about

2 to 5 gallons of water per qycle out of an average use of 14 to 15 gallons in

the "normal cycle".

Limited testing on dishwashers, using 5/4 and l/2 of the normal water per

fill indicates degradation of washing performance, making this technique

unacceptable for the user with currently designed machines. The dishwashers

would have to be redesigned since with reduced water per fill the lower spray

arm and upper water distribution systems malfunction and washing action is

inhibited. Redesign would involve altering the geometry of the dishwasher sump

region and the pumping and spray system to accommodate reduced water per fill.

Recently, to save energy, some manufacturers have incorporated some of these

features with the result that the amount of water used has been reduced by 1 to

2 gallons per cycle. As a result of these tests on earlier designed appliances

it is concluded that reducing fill volume is not a satisfactory method for water

savings in a dishwasher without engineering modifications to the water pump and

spray system.

8.2 Discharge Water

Tests to determine the relative percentage of food particles removed during

each water change by a dishwasher, either by a wash or rinse in the normal

cycle, indicate that the soil content of the last three water discharges is low

enough to permit the use of this water in a stored grey water recycling system.

The grey water would be used to supplement the water required to remove solid

wastes in a household sewer system and thereby conserve potable household water.

9* Conclusions

For determining the most water-efficient fill level for clothes washers,

the variance of the soil removed from test swatches, rather than the average

value of the soil removed, appears to be the best indicator for performance.

Defining optimum water-conserving fill level as the level at which reductions in

fill volume result in a marked increase in variance, a fill level guideline for

consumers is suggested: load the machine, pack the clothes moderately, and fill

the machine to the height of the clothes load using a fixed point on the

agitator or tub as a reference point. For the clothes washers evaluated, each

inch of water in the washer tub corresponds to approximately 2 gallons of water.

17
Use of the suggested fill method will permit satisfactory performance and also

achieve water conservation.

Dishwasher performance degrades upon elimination of rinse subcycles,

however, the large variability in both dishwasher design/performance and extent

of dishware soiling, precludes blanket recommendations re^rding the use of

short cycle settings. Rather, consumers should be made aware of the water and

energy savings associated with the various cycle settings, and be urged to

experiment with them.

Additional research is still needed in several appliance-related areas,

particularly:

o development of improved methods or schemes for rating appliances.

Such methods would take into consideration water and energy

consumption as well as performance in obtaining a measure of

"overall" efficiency.

o analyses of tradeoffs between appliance water and energy usage, water

temperature, washing time and other parameters, with the objective of

reduced water and energy consumption without increased cost to consumers.

o biological studies of appliance discharge water, for application to

grey water recycling/sweep systems.

18
10 . References

1. Palla, R. L. , Water Usage Characteristics of Household Appliances, and the

Potential for Water Savings, National Bureau of Standards NBSIR 80-21.73,

Washington, D. C., December 1980.

2. Laundry Practices of Normal and Large Capacity Automatic Washer Owners, The

Procter & Gamble Company (1970).

3- Bailey, J. R., Benoit, R. J., Dodson, J. L. , Robb, J. M., and Wallman, H.

,

"A Study of Plow Reduction and Treatment of Waste Water from Households,”

Water Pollution Control Research Series, U.S. Environmental Protection

Agency, Washington, D.C. (December 19, 1969).

4* Cohen, S., and Wallman, H., "Demonstration of Waste Plow Reduction from

Households," Environmental Protection Technology Series, National Environmental Research Center, Environmental Protection Agency, Cincinnati, Ohio

(September 1974).

5. McLaughlin, E. R. , "A Recycle System for Conservation of Water in

Residences, Proceedings of a Conference on Water Conservation and Sewage

Plow With Water Saving Devices, Sharpe, W. E. , and Fletcher, P. W. , ed..

The Pennsylvania State University, University Park, Pennsylvania (July

1975). State University, University Park, Pennsylvania (July 1975).

6. Federal Register, 42, No. 152 (Monday, August 8, 1977), Part 430 - Energy

Conservation Program for Appliances "Test Procedures for Dishwashers",

Appendix C.

7. American National Standard A197* 5-1975, AHAM DW-1, Household Dishwashers,

Association of Home Appliance Manufacturers.

8. Gordon, C. C., "Lower Water Consumption in Home Dishwashers", NBS (October

1977), Milestone Report for Department of Energy.

9* Gordon, C. C., "Energy Consumption of Foreign and U.S. Dishwashers" NBS

(Aug. 1979), Milestone Report for Department of Energy.

10. Gordon, C. C., "No-Heat Drying of Dishes for Energy Conservation" NBS (Aug.

1977), Milestone Report for Department of Energy.

19
TABLE 1-

CHARACTERISTICS

OF

CLOTHES

WASHERS

TESTED ? x

xx 05 05 05 oo CO

LaJ

O£r— r— r—

x

X

Q

C i i fl 05 05

O UJ CO CO CO r— r-— s; >- x x x 05 cr> CTl ' r— r— o «c CO 00 *3- i— • • • • o 00 CO X o o 1

r— CM CM CM CO

>—1

CO u_ o z: _J 25 UJ

z: _i c l C_5 CD 3 >- CM 00 05 LO If) *—<

c_> • • • • • l s: CO 05 r— CO

DC r— r— < OO

z: et —O 3 « 1a.

s:roCO2: < CO o »— 00 CO

X o O • • • • _i 1— o ff— CO CO ad _i LO in

UJ *—« 1

U-

<c

3: s:

2) UJ S __J HH <_5 CO X >- IX

X r— <o < o • • • • s: CO 00 LO 05 r=“ DC CM r— CM f—»

CM OO

<c3

CO1— •*—1 00 8-0 00 to o OC 3 • • • UJ h- ir> ILO uo to 3 a. 3 UJ

*-i

Q ' 1 *

a> M c o m t- c 3 8 I— oc m

UJ *o Cd h- ID 00 LT> 00 uo

UJ UJ • • • • M 3 Z O o r— o o CL 3 < CM CM CM CM CM <U » « »—* u Q X

at T5 T5 •a

(O fd <o OO o O o

CD q=

C£ —1 3 U1— UJ M T5 T3 o > 1— CT5 CO C C c <UJJ- 3 3 3 3 _l ui O O o

oo CL o_ CL

ir> o>

JC JC

4-» -M 4-> 1— 1— r— CM CO UO •r— •r— OO >—1

UJ 3 3 3 3 3 3 3 3 O <_5 c_> C_5 <_> h- 25 1 1 l <C CO <_) 20
TABLE

2

-

PERFORMANCE

RELATED

PARAMETERS

21
TABLE 3

WATER USAGE - FILL LEVEL RELATIONSHIPS

TEST UNIT SLOPE* - M INTERCEPT* - b

CW1 0.544 -0.873

CW2, CW4 0.616 -0.328

CW3 0.575 -0.687

CW5 0.553 -0.681

Fill Level = M- (Water Usage) + b

Where

Fill level is inches

Water Usage is in gallons

22
TABLE

4

-

FILL

HEIGHTS

AND

TEST

LOAD

HEIGHTS

23
TABLE 5

DISHWASHER CYCLE PHASING AND WATER CONSUMPTION

Test

Unit

Water Consumption

Subcycle

*

» **

gallons

Total

• R W R R R

• DW1 2.6 3.1 3.1 3.1 3.3 15.2

W R W R R

DW2 2.4 2.0 2.0 2.1 2.1 10.6

R W R W R R

DW3 2.1 2.2 2.7 2.2 2.2 2.3 13.7

W R W R R R

DW6 2.2 2.2 2.2 2.2 2.2 2.2 13.2

W R R W R R R

DW7 2.7 1.8 1.8 2.7 2.7 1.8 2.7 16.2

W R W R R R

DW8 2.4 2.7 2.7 2.7 2.7 1.5 14.7

W R R W R R

DW10 2.4 2.4 2.4 2.4 2.4 2.4 14.4

“"Supply pressure = 35 psig flowing

**W = Wash, R = Rinse

24
TABLE 6

PERCENTAGE OF DISHWARE REWASHED

Total pieces washed =136 (dishes and flatware)

Dishwasher

Unit

Volume

per Fill

Total pieces

rewashed

%

rewashed

A 3/4 34 25

A 1/2 58 43

B 3/4 27 18

B 1/2 37 27

C 3/4 62 46

C 1/2 85 63

D 3/4 99 73

D 1/2 114 84

25
1VA0H3U HOS i.N30a3d

26
.5

10.0

IIS

15.0

17.5

20.0

223

25.0

273

WASH

WATER

USED

(GALLONS)

FIGURE

2.

SOIL

REMOVAL

VARIANCE

VERSUS

FILL

LEVEL

— 7

POUND

LOAD
o

28

7

A

\ojo

ns

is.o

ns

mo

22s

WASH

WATER

USED

(GALLONS)

FIGURE

3.

AVERAGE

SOIL

REMOVAL

VERSUS

FILL

LEVEL

—

CW1
o

29

76

10.0

126

».0

17.6

20.0

226

WASH

WATER

USED

(GALLONS)

FIGURE

4.

SOIL

REMOVAL

VARIANCE

VERSUS

FILL

LEVEL

—

CW1
AVERAGE

°o

SOIL

REMOVED

IN

EACH

DRAIN

AVERAGE

%

SOIL

REMOVED

IN

EACH

DRAIN

100 100 DISHWASHER, UNIT A (AVERAGE FOR 4 TESTS)

FULL FILL NORMAL CYCLE

WATER CHANGES

W = Wash

R = Rinse

3 4 DRAIN NO.

u

2

90

80

70

60 aU4{ 50

LU

OC5 40

CO3 30

20

10 h

0

DISHWASHER, UNIT B (AVERAGE FOR 3 TESTS)

FULL FILL NORMAL CYCLE

WATER CHANGES

W = Wash

R = Rinse

2 3 4 DRAIN NO.

100

90

80

70

60

50

40

30

20

10

0

DISHWASHER. UNIT C (AVERAGE FOR 3 TESTS)

FULL FILL NORMAL CYCLE

WATER CHANGES - W Wash

1 2 3 4 5 6 DRAIN NO.

CJ2

1 2 3 4 5 6 7 DRAIN NO.

FIGURE 5: SOIL REMOVAL PER SUBCYLE—ALL UNITS AT FULL FILL

30
NIVUQ H3V3 hi Q3A0W3H 1I0S %

NIV8Q H0V3 Nl Q3A0W38 DOS %

NIV80 H3V3 Nl Q3AOW3U 1IOS % 39V83AW

31

FIGURE

6:

SOIL

REMOVED

PER

SUBCYLE-UNIT

A;

FULL,

3/4,

and

1/2

FILL
oooooooo

NIVUQ H3V3 Nl Q3AQW3M 1I0S %

NlVdQ H0V3 Nt Q3AOW3d HOS % 39V83AV

32

FIGURE

7:

SOIL

REMOVED

PER

SUBCYCLE-UNIT

B;

FULL,

3/4,

AND

1/2

FILL
NIVUO H3V3 Nl 03A0W3H 1IOS %

NlVdO H3V3 Nl Q3AOW3a 1IOS % 3DVH3AV

33

FIGURE

8:

SOIL

REMOVED

PER

SUBCYCLE-UNIT

C;

FULL,

3/4,

AND

1/2

FILL
NIVUO H3V3 Nl O3A0W3U 1IOS %

NIVUO H3V3 Nl 03A0W3U 1IOS % 33VU3AV

34

FIGURE

9:

SOIL

REMOVED

PER

SUBCYCLE-UNIT

D;

FULL.

3/4,

AND

1/2

FILL
NBS-I14A (rev. 2-80

U.S. DEPT. OF COMM. 1 . BIBLIOGRAPHIC DATA

SHEET (See instructions)

PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No.

NBSIR 81-2291

3. Publication Date

May 1981

4. TITLE AND SUBTITLE

Performance Aspects of Water Conservation Techniques for Appliances

5. AUTHOR(S) , ^ ,

,

Charles C. Gordon and Robert L. Pal la, Jr.

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No. national bureau of standards

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Department of Housing and Urban Development

10.

SUPPLEMENTARY NOTES

; 1)1

J Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

The performance of household clothes washers and dishwashers is evaluated

assuming various water conservation methods. For clothes washers the effect

of fill level setting on soil removal is presented. A guideline for setting

fill level is suggested. For dishwashers the soil removal capabilities are evaluated at reduced fill volumes. An analysis of the percentage of soil

removed for each wash/rinse subcycle shows the relative quantities of soil in

"the discharge for each subcycle.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Clothes washers; dishwashers; dishwasher subcycles; fill controls; grey water;

performance; soil removal; water conservation; water discharge characteristics

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Q3] For Official Distribution. Do Not Release to NTIS

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~ 15. Price 20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

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