NBSIR 78-1500

Application of Life Cycle Costing

to Hand-Held Hair Dryers: A

Field Demonstration for Small

Appliances

S. Wayne Stiefel

P. Clare Goodman

William B. Beine

Consumer Sciences Division

Center for Consumer Product Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

May 1978

Final Report

Prepared for National Bureau of Standards

Department of Commerce

Washington, D.C. 20234

NBSIR 78-1500

APPLICATION OF LIFE CYCLE COSTING

TO HAND-HELD HAIR DRYERS: A

FIELD DEMONSTRATION FOR SMALL

APPLIANCES

S. Wayne Stiefel

P. Clare Goodman

William B. Beine

Consumer Sciences Division

Center for Consumer Product Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D C. 20234

May 1978

Final Report

Prepared for National Bureau of Standards

Department of Commerce

Washington, D.C. 20234

U S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman. Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Acknowledgments

The writers gratefully acknowledge the contribution

of Elizabeth Robertson, who structured and conducted the

survey of small appliance repair firms. Ruth Warnock

also deserves thanks for her conscientious secretarial

assistance in the preparation of this manuscript.

11
Contents

Page

Acknowledgments j_i

Abstract 1

1. Introduction 2

1.1 Background 2

1.2 Objective 3

1.3 Approach 3

2. Hair Dryer Field Experiment 3

2.1 Purpose 3

2 . 2 Methodology 4

2.2.1 Selection of Hair Dryers 4

2.2.2 Selection of Participants 4

2.2.3 Data Collection Procedures (NBS

Families) 6

2.3 Participant Description

2.3.1 Questionnaire Usage Results 9

2.3.2 Comparison of Recalled Estimates with

Measured Values 12

3. Repair Agency Survey 17

3.1 Survey Process 17

3.2 Results of the Interviews 18

3.2.1 Most Frequent Repairs 18

3.2.2 Cost for Service (labor and parts) . . 19

3.2.3 Parts Cost 19

3.2.4 Causes for Failure 20

3.2.5 Repair versus Replacement 20

4. Used Hair Dryer Analysis 21

4.1 Collection Process 21

4 . 2 Results 21

5. Computation of Life Cycle Ownership Costs 24

6. Conclusions 28

Appendix A. Analysis of Sample Size for Hair Dryer

Experiment 30

Appendix B. Usage Data Summary 32

Appendix C. Comparison of Usage Values for Survey

Response and Meter Estimates 37

Implications for Future Field Studies . .

iii

Appendix D. 42
List of Tables

Table

No. Page

1 Usage pattern survey instrument #1 8

2 Usage pattern survey instrument #2 8

3 Comparison of market survey frequency of use

to field study results 10

4 Instrument box convenience assessment 11

5 Hair dryer performance problems 12

6 Ranking of most frequent repairs 19

7 Repair fee estimates. 19

8 Parts cost estimates 20

9 Age of hair dryers collected 22

10 Evaluation of hand-held blowers collected .... 23

11 Computation of cost of energy 25

B-l Questionnaire raw usage data 33

B-2 Sex and age of NBS hair dryer participants. ... 34

B-3 Hair length and thickness of NBS hair dryer

participants 34

B-4 Room most often used to dry hair by NBS hair

dryer participants 35

B-5 Meter readings raw data 36

C Calculated usage values 41

D Organizational structure for conducting field

studies 43

IV
List of Figures

Figure

No. Page

1 Total hours of hair dryer operation: comparison

of metered versus recalled estimates during

approximately 9 weeks of field use 14

2 Total on-off counts: comparison of metered

versus recalled estimates during approximately

9 weeks of field use 15

3 Minutes per on-off cycle: comparison of

metered versus recalled estimates during

approximately 9 weeks of field use 16

4 Average ownership cost for a 1000 watt blow

hair dryer (excluding repairs) versus year of

retention 27

C-l Accumulated hours per dryer 38

C-2 On-off cycles per dryer 39

C-3 Minutes per on-off cycle 40

v
1 . 2 Objective

The objective of this study was to collect information

on hair dryers, aid development of life cycle performance

test methods and characterize costs as a function of time.

The project was a demonstration study on hair dryers to

provide insights into the processes and techniques which can

be used in the application of the LCC technique for a small

appliance where the consumer is a significant factor in its

usage

.

1 . 3 Approach

Two parallel approaches were utilized during this

project. Field data collection methods, intended to develop

information on usage, repair and cost information,

constituted the efforts which are documented in this report.

Laboratory test method development efforts will be

documented in a forthcoming NBS report.

The field data collection included a pilot field

experiment to collect usage and repair data from consumer

participants provided with specially instrumented hair

dryers. Repair incidence and repair cost data were also

collected by two other methods. First, used hair dryers

were collected from volunteers for failure mode analysis.

Second, repair agencies were surveyed for repair and service

cost data.

2. HAIR DRYER FIELD EXPERIMENT

2 . 1 Purpose

A hair dryer field study experiment was designed for

three reasons: (1) to ascertain energy consumption, usage

information and failure data from hand-held hair dryers; (2)

to provide field data to compare with data obtained from a laboratory test procedure; and (3) to demonstrate the

procedures for field monitoring of hand-held and other small

appliances

.

In addition to the instruments provided to record

usage, a questionnaire was designed to obtain two types of

information: namely, usage patterns and personal user

characteristics. Information on usage patterns was sought

for two reasons. First, since many previous studies have

relied entirely on user recall as a means for obtaining

3
usage data, it was desired to observe the correspondence

between measured data and user estimated data. Second, the

measuring instruments could not supply certain types of

usage data, such as the temperature setting which affects

energy consumption.

Personal data were collected to determine the

composition of the participant group for possible comparison

with other studies. Additionally, this information would

facilitate any future analysis of failure characteristics,

such as the correlation between length of hair and time to

failure. The sample was not originally intended to be a statistical representation since families with more than one

user were favored over single users, especially single users

with low usage rates.

2 . 2 Methodology

2.2.1 Selection of Hair Dryers

A preliminary laboratory study was conducted involving

15 brands of hand-held blow hair dryers. Based on the

preliminary tests, a model with a fairly high rate of

laboratory failures was selected for further laboratory test

method development and use in the field experiment.

The sample size required for the field study was

determined by following a statistically based estimation

procedure. 2 The preliminary laboratory study of dryers was

used as an initial sample to calculate a mean failure time

and a standard deviation that were needed to estimate the

total required sample size for the second laboratory study

and the field study. Equations and detailed calculations

are given in Appendix A.

2.2.2 Selection of Participants

Sixty hair dryers were distributed equally among two

sets of participants:

(1) Families of NBS employees providing "normal" use.

(2) Local hair cutting salons providing "heavy" use.

2 Mary Natrella, Experimental Statistics , National Bureau of

Standards, Handbook 91, October 1966, pp. 2-10.

4
The two sets of participants were selected with distinctly

different purposes in mind. Family participants provided

data on dryer usage (frequency of use and duration for each

use) . Hair salons were selected to provide data on failures

(time to failure and failure modes) within a relatively

short period of time.

The family participants were selected from volunteers

responding to several notices placed in the weekly NBS

Technical Calendar. Prescreening information was obtained

from those volunteers who indicated interest in

participating in the study.

The prescreening information included the following:

• NBS office location and number. All contacts were

made at NBS

.

• Type of hair dryer presently being used. This was

asked in order that dryers be distributed only to

persons who were already using a hand-held blow

hair dryer.

• Number of persons in the family who would use the

dryer and probable frequency of use. From these

questions an estimate was made for the total

amount of use the dryer might receive. Families

who would use dryers less than two times per week

were not selected.

• The outlet location for the hair dryer. Families

who did not plug their dryer into a standard size

outlet could not participate. The instrument box

located at the end of the power cord was too large

to fit into most medicine cabinet outlets.

Prescreening information was collected for 50 volunteer

families. From these volunteers a sample of 30 participants

and 5 alternates were selected. Acknowledgements of

appreciation were mailed to all volunteers who were not

selected. Those selected were mailed a letter describing

the study and informing them about Participant Agreement

forms that had to be signed by all potential study

participants. During the following week these forms were

collected. For privacy, a folder for each participant

family was numbered and names were matched to numbers on a separate list located in a different office. The

5
preliminary information as well as the participant agreement

forms were kept in these folders.

A demonstration of the operation of the hair dryer,

including the location of the control settings, was given

when each NBS employee picked up a study dryer. At this

time participants were also asked to read the instruction

booklet and insure that each user of the dryer in their

family also read the booklet and understood the operation of

the hair dryer.

The second set of participants were beauty salon

operators who use hair dryers several times per day.

Locating hair salons willing to participate using the hair

dryer selected proved to be unproductive. Few salons were

willing to use 1000 watt dryers. Most of them wanted

something that would produce more heat, such as a 1200 or

1500 watt dryer. Even beauty salons that used 1000 watt

dryers on a regular basis found the study dryers to be

unbalanced or too bulky for continuous use. The following

list summarizes the type of complaints that were heard from

beauty salons, about the study dryers:

• Doesn't dry fast enough.

® Not hot enough.

• Hard to handle.

• Heavy and bulky.

• Could not find a place to plug in the black box.

A number of hair cutting places tried the dryers, but none

appeared to be satisfied enough with their operation to

continue using them. Consequently no use data was obtained

from this set of participants.

2.2.3 Data Collection Procedures (NBS Families)

The instrument box, containing the elapsed time and

frequency count meters, also served as the dryer's

electrical plug and was attached to the plug at the end of

the hair dryer power cord. The box's dimensions

necessitated use of a wall outlet as opposed to a medicine

cabinet outlet. The purpose of the time meter was to

measure the total cumulative time the dryer was in

6
operation. The purpose of the counter was to measure the

number of times the dryer was turned on. The number of

counts obtained should not be taken to represent the number

of times the dryer was used since a dryer is typically

turned off and on again several times during a single drying

process. An interruption, such as answering a telephone, or

a routine practice, such as putting in hair curlers, results

in more than one on-off count during a single drying period.

Therefore, it is important to note that the meter used for

this field study measures the number of times the dryer was

turned on.

In addition to meter results, users were asked to

estimate their usage based upon personal recall. The

information obtained from the two approaches complement one

another and allows for the comparison of recalled versus

metered responses.

During August 1977 each study participant completed the

questionnaire concerning their usage patterns. Table 1 is a copy of the first questionnaire. In September 1977 it was

discovered that an additional question should be asked; it

is shown in table 2. The results of these questionnaires

are reported in Appendix B of this document. The results

reported are representative of 9 to 11 weeks of use attained

during FY 77. The study is continuing and participants have

retained the dryers to accumulate additional use and failure

data

.

In compliance with requirements of the Privacy Act, a system was established to protect against the disclosure of

the personal information collected.

2 . 3 Participant Description

The number of persons using a dryer in a single

household ranged from one to four. A total of 68 people

were using the 30 dryers. This translated to an average of

2.26 users per dryer. Three families chose to stop

participating at the end of the fiscal year 1977, the

remaining families all agreed to continue. One new family

was added and assigned one of the dryers from a family no

longer participating.

For each participant, the following personal data were

collected and tabulated: age, sex, thickness of hair,

length of hair, and room most often used to dry hair.

7
Table 1. Usage pattern survey instrument #1.

Dryer #

W< would appreciate each person using the study hair dryers taking a few

iMinutes t o answer t he following questions.

Sex

Male Female

How would you describe your hair?

Age

under 10 10-15 16-21 over 21

How long is your hair?

Thick Short

Medium Collar length

Thin Shoulder length

Longer than shoulder

Do you routinely use hair spray before you finish using the hair dryer?

| | Yes

No

Approximately, how many times per About how many minutes do you spend

week do you use the hair dryer? each time drying your hair with the

dryer?

times minutes

Estimate the percentage of time you use the dryer at each temperature

setting

.

High % Low % Medium % Cool % Above entries should total 100%

In which room do you most often dry your hair?

Bathroom Living room Bedroom

Kitchen

Other (Please describe)

Did you find the attached black box inconvenient?

NO

Yes--Explain

Did the dryer perform abnormally at any time? For example, stopped and

started by itself while drying, did not produce heat, smoked, etc.

Please explain

Table 2. Usage pattern survey instrument #2.

Is the hair dryer normally turned on and off more than once during each

drying use?

I 1 Yes * How often?

I I No

Sex

| Male | Female I Age

under 10 10-15 16-21 over 21

8
Excellent cooperation was received from all questionnaire

recipients, with a 100 percent response rate. Appendix B

contains tables summarizing these data.

The participants included 43 females and 25 males.

Approximately half of the participants were over 21 years of

age. The younger participants (21 or under) were much more

likely to be female while the older participants were

equally divided among males and females. Most participants

had either short or collar length hair, which tended to be

of medium thickness, with only a few thin-haired

participants

.

2.3.1 Questionnaire Usage Results

The bathroom was the room most often used to dry hair

by 65 percent of the participants. The bedroom was most

used by 32 percent (see Appendix B, table B-4). A 1975

national market survey on hand-held styler/dryers reported

that 59.6 percent of the dryers were used in the bathroom

most of the time, and 27.6 percent were used in the bedroom. 3

Each participant was asked to estimate the following:

(1) average frequency of dryer usage per week; (2) minutes

per use; (3) on and off's per use; and (4) percentage of

time at each temperature setting. Together, (1) and (2)

yield "accumulated hours per dryer"; (1) and (3) yield "onoff cycles per dryer"; and (1), (2), and (3) yield "minutes

per on-off cycle." 4 These calculated values can be compared

to the measured data obtained from the instrument box.

Average frequency of dryer usage per week as estimated

by this study can be compared to other studies. Among NBS

families the average number of uses per week was 4.35.

Comparison of the distribution of frequency data (table 3)

Proprietary report.

4 See Appendix C for histograms of each of the three categories

of data described above.

9
by MBS families and a 1975 national market survey on handheld dryers reveals that roughly similar percentages of

people use the dryer 1-2 and 3-4 times per week. Among

frequent users of hair dryers, the sum of the 5-6, once a day, and more than 7 times per week categories are

comparable. Many more people in the national study claimed

use of the dryer once a day, rather than slightly more or

slightly less.

Table 3. Comparison of market survey frequency

of use to field study results.

Frequency of use Field results National survey

More than 7 times per week 10% 1.5%

Once a day 13% 38.3%

5-6 times per week 16% 1.8%

3-4 times per week 34% 29.3%

1-2 times per week 27% 27.3%

Less than 1 time per week 1.7%

The questionnaire also solicited other information,

such as hair spray use, convenience of instrument box and

perceived performance problems.

It is possible that hair dryer failures could result

from use of hair sprays. Only one person in this study

reported routinely using hair spray before finishing use of

the dryer. Since this represents only one percent, a

substantial number of failures due to hair spray is

unlikely.

The instrument box or "black box," located at the end

of the power cord, was judged to be inconvenient by 26

percent of the users. Table 4 lists the reasons given by

these people.

10
Table 4. Instrument box convenience assessment.

Did you find the black box inconvenient?

No 50 or 74%

Yes 18 or 26%

Following were the reasons given (more than one reason was

given on a few occasions)

4 Furniture had to be kept away from the wall, due to the

size of the box.

5 Box would not fit in certain outlets (bathroom)

.

3 Box was too large/bulky.

2 Had to use an extension cord.

2 Box was inconvenient for storage.

1 Box would not stay in wall socket.

1 Box caused power cord to become twisted.

1 Box was ugly.

1 Box would not fit in a wall socket that already had a plug in the bottom position.

Only a few dryer performance problems were reported.

Table 5 lists the problems cited by participants. All of

the problems with the 30 dryers were reported by four

families

.

11
Table 5. Hair dryer performance problems.

Did you experience any performance problems?

No 62 individuals (91%)

Yes 6 individuals (9%)

Following are the problems given:

2 "Not powerful enough."

1 "A couple of times the dryer sounded like it was going

to stop."

1 "Once when only one switch was pushed to high and the

other one on "off" there was no air and the coils

inside turned bright red."

1 "A few times it would produce a smoky smell like

burning hair."

1 "Slowed down brief ly--then up to speed."

1 "Slowed down for 2-5 seconds during drying, but it

resumed normal operation by itself —may be line voltage

fluctuation .

2.3.2 Comparison of Recalled Estimates with Measured Values

During 1975, an experimental study 5 on hair dryer usage

was conducted in the NBS Human Factors Laboratory. Twenty

subjects were requested to dry their hair using their own

dryer while their activities were monitored and videotaped.

The average drying time of these 20 laboratory sessions was

seven minutes. The subjects were also requested to complete

a brief questionnaire concerning their home use of the

dryer. The average reported drying time at home was 12

minutes. A large difference between the self -estimated use

time and the laboratory use time is evident. It could be

postulated that the difference in location and the

experimental circumstances influenced the use period. The

measuring of use cycles in home environments would provide

additional indications if an overestimation pattern by users

should be expected.

5 Stefl, Mary, Electrical Appliances: Hand-Held Hair Dryers,

Interim Report CPSC Project No. 132, Unpublished draft.

May 10, 1976.

12
Many studies have relied upon consumer estimates as the

means for obtaining usage data on appliances. In this study

it was possible to contrast recalled results with measured

values to evaluate their comparability. The raw usage data

from both the metered values as well as the recalled survey

responses obtained from the individual users have been

tabulated in Appendix B. The hair dryers were used

approximately nine weeks prior to reading the instruments

(which provided estimates of total hours of operation and

on-off counts for each of the dryers) . Comparable recalled

values have been computed for each hair dryer using

appropriate weighting factors for each of the dryer users.

These values and their methods of computation are shown in

Appendix C. Comparisons were made between the recalled

survey and metered estimates for the total hours of

operation, total on-off cycles and minutes per on-off cycle.

Figure 1 compares the total estimated hours of

operation for each hair dryer as read from the meter and as

calculated from the recalled survey. A perfect

correspondence would result in all points lying on the "45

degree line." In only two cases, which occurred at low

usage values and within the measurement error, was the

recalled estimate lower than the meter reading, and in two

more cases the recalled estimate and meter reading were the

same. All the remaining cases involved recalled estimates

exceeding metered estimates. In many cases the survey

estimate is several times that of the meter reading. A

least squares fit of the points is also shown in figure 1.

The average estimated hours of operation was 13.8 for

recalled and 4.1 for metered values.

Figure 2 illustrates graphically a comparison of the

two estimates for total on-off counts. The recalled values

were summed for each user for comparison with the meter

values. Again, perfect correspondence would result in all

points falling on the "45 degree line." As in the case of

hours of operation, recalled values far exceed metered

values for the vast majority of dryers.

Figure 3 provides the data on minutes per on-off cycle.

The pattern of recalled exceeding metered values is once

again repeated.

An important conclusion can be drawn from observing the

scatter shown in figures 2 and 3 when comparing the metered

and estimated values. No adequate relationship between the

recalled and metered values can be established, because of

13
40

30

Hours of 20

Operation

(metered)

10

0

Metered = Recalled Response

XXX X T X X ' X

X

X X x x_ -K-X X Y=AX+B

x X

~i 1 1

1 1 1 1 1 t1 r1 1 1 1 1 1 s

0 10 20 30 40

Hours of Operation (recalled estimates)

Figure 1. Total hours of hair dryer operation:

comparison of metered versus recalled

estimates during approximately

9 weeks of field use.

14
Figure 2. Total on-off counts: comparison of

metered versus recalled estimates during

approximately 9 weeks of field use.

15
8

Minutes per

On-Off Cycle

(metered)

^

0

/ Metered = Recalled Response

x / / /

/

/ /

* *

/

/ / X

l—I—l—I——i—

r

0.0 2.5

Y=AX+B

t

1—i—i—i——i—i—i—i—’—i—i—i—i

1—i—i—i—i——i—i—

r

5.0 7.5 10.0 12.5 15.0

Minutes per On-Off Cycle (recalled estimates)

Figure 3. Minutes per on-off cycle: comparison of

metered versus recalled estimates during

approximately 9 weeks of field use.

I

1—

17.5

16
the poor correlation between the data and the fitted curve.

Furthermore, the discrepancy between the line representing

exact correspondence and the best fitted line points out the

need for good measured data to draw accurate and reliable

conclusions about usage.

3. REPAIR AGENCY SURVEY

3 . 1 Survey Process

The objective of this survey was to examine the use of

repair agencies as a source for repair cost data and as a

means to identify the most frequent hand-held blow hair

dryer failures. To expedite the data collection, firms

specializing in the repair of small electric appliances were

sought. Several firms across the country were willing and

capable of estimating repair costs and identifying the most

frequent repairs performed.

This pilot survey was designed to investigate

interviews and questionnaires as methods for acquiring

information and data on small appliance failures,

particularly hand-held blow hair dryers. Since it was a pilot survey, the number of interviews was limited, in this

case to nine respondents. Because of the limited numbers,

the survey can not be assumed to be statistically

representative of repair agencies.

Respondents included:

1. Four local appliance repair firms listed in the

yellow pages.

2. Four members of the National Appliance Service

Association (NASA)

.

3. One manufacturer.

NASA, located in Kansas City, Missouri, is a group of 125

firms who are owners of factory-authorized appliance centers

servicing small electrical appliances. The four members

interviewed were scattered throughout the U.S.

The interviews were conducted using the telephone. The

persons being interviewed were assured that no identifiers

would be associated with the information collected.

Although a schedule of questions was used to guide the

17
conversation, the interviewer was free to pursue areas the

repair expert believed to be pertinent. In this way all

questions on the schedule were addressed in each interview

and additional information was collected which could not

have been obtained from a set format of questions.

The schedule covered items referring to the problems

consumers experience with dryers and with their repair, as

well as costs for repair. In addition, the service agency

was asked about their problems in providing service. The

schedule used was

What kind of problems do people have with hand-held

blow dryers? What is the most frequent problem you see

coming into your shop? About how many dryers do you

see (come in for repair) in an average week? How much

time is involved in the repair? Does your shop perform

the repairs? How much does it cost, on the average?

How old are the dryers which come in for repair? Are

some dryers, because of design, either difficult or

impossible to repair (for example, sealed units)? In

that case, how does the customer get his dryer

repaired? Do you have any difficulty getting parts for

some brands? How much do the parts cost?

3 . 2 Results of the Interviews

3.2.1 Most Frequent Repairs

Table 6 gives the number of times each repair was

mentioned and how many times the repair was ranked as being

the most frequent. Included in these data are results from

five earlier contacts with manufacturers made in a preliminary investigation.

18
Table 6. Ranking of most frequent repairs.

Repair Problem

No. of times

mentioned

No. of times

ranked 1st

Heating element 10 4

Cords 7 6

Cleaning 7 1

Fuse 6 2

Switches 5 - Fans 3 - Motor 3 - Thermostat 2 —

3.2.2 Cost for Service (labor and parts)

The average cost including labor and parts to repair a dryer in general was $7.78. The lowest recorded cost was

$3.50; the highest was $11. Table 7 lists the repair fees

typically charged represented by the average cost and the

highest and lowest cost reported for particular repairs.

These figures are inclusive of labor and parts as the repair

firms tended to discuss a "flat price" rather than to

calculate time and material costs separately.

Table 7. Repair fee estimates.

Repair of ... Average cost

Lowest cost

reported

Highest cost

reported

Cords $5.63 $3.50 $ 7.00

Heating element 9.50 8.00 11.00

Fuse 5.71 6.00 7.85

Switch 5.93 3.50 7.85

Fan 5.68 3.50 7.85

Thermostat 5.68 3.50 7.85

Clean 6.93 3.50 7.85

3.2.3 Parts Cost

Only a few of the respondents reported the costs of

particular parts. Table 8 shows the part, the average cost

and the lowest and highest cost reported.

19
—

Table 8. Parts cost estimates.

Part

! Average cost Lowest cost

reported

Highest cost

reported

Cords $2.25 $1.50 $3.00

Fuses 1.33 . 65 2.00

Elements 3.24 2.95 4.95

Switches 1.45 .95 1.95

Motor brushes

1 1.00 1.00 1.00

3.2.4 Causes for Failure

Many different causes for failure were mentioned during

the interviews. One of the most frequently mentioned causes

was the impeding of air flow thereby causing overheating.

Blocking of air flow can result from build up of dirt, lint

or hair; or from laying the dryer down while in operation in

a manner that blocks the air intake. Another common cause

of failure was the dropping of dryers resulting in damage to

elements, switches and fans. One firm claimed the majority

of dryers brought to it are not operating due to strain

relief failure in line cords. Other failures result from

dirt or hair lodged in bimetallic contacts and hair wrapped

around motor shafts.

3.2.5 Repair versus Replacement

The decision to repair or to replace a blow hair dryer

appears to be dependent upon parts accessibility and the

cost for repair. Repair agencies generally do not stock

parts for all hair dryers and obtaining parts sometimes

results in lengthy delays. Two repair firms stated that if

the cost for repairs exceeded eight or nine dollars it is

better for the customer and the repair agency to offer a replacement dryer at a few dollars above their cost. Motor

replacement costs are not listed in table 7 because the

repair firms surveyed felt this cost to be prohibitive for

most customers.

20
4.

USED HAIR DRYER ANALYSIS

4.1 Collection Process

Used hair dryers (blow- type and stylers) were collected

from NBS and other government personnel for a general

analysis of hair dryer condition and failures as a function

of construction and age. The procedure for this collection

involved placing several notices in the NBS Technical

Calendar requesting hand-held blow hair dryers that were no

longer in use, whether operative or non-operative. At the

time the dryers were collected, the following information

was recorded:

1. Brand name.

2. Rated wattage.

3. Age of hair dryer.

4. Number of users.

5. Uses per week for each user.

6. Time per use for each user.

7. Reason for donation, if known.

The condition of collected dryers was analyzed and an

attempt was made to determine the reason for failure if the

unit was inoperative.

4 . 2 Results

A total of 54 hand-held hair dryers were collected; 17

were hand-held blowers and 37 were hand-held stylers. The

blowers were of more interest to this study since blowers

were being used for the field study and in the laboratory

evaluation

.

The age of the hair dryers collected varied but the

majority of the dryers were either fairly new or relatively

old and out-of-date. The oldest styler was five years, with

the vast majority between one and two years. The blowers

more clearly divided into two groups with 35 percent two

years or younger and the remaining 65 percent six years or

older. Table 9 shows the age distribution for all the units

collected.

21
Because the survey cannot be assumed to be

statistically representative, the results of the interviews

can only be used to suggest the types of failures which

might occur—not the frequency expected in the field.

Table 9. Age of hair dryers collected.

Less than

1 year

1-2

years

3-4

years

5-9

years

Old or 10

years or more

All No. 9 28 5 3 9

Dryers % 17 52 9 6 17

Blowers No. 2 4 0 2 9

Only % 12 24 0 12 53

Stylers No. 7 24 5 1 0

Only % 19 65 14 3 0

Even though stylers were collected, blowers were

analyzed more carefully for condition status and cause of

failure. Of the 17 blowers, 11 operated, at least to some

degree, and were divided into one of the following three

categories

1. Running poorly overall, or motor running slower

than it should.

2. Operating acceptably with nothing apparently wrong.

3. Old enough to be considered out-of-date.

The remaining six were clearly broken or involved some type

of failure. The six problems were as follows: loose fan

blade, bent shaft, bad thermal element, shorted coil, broken

wire and broken heater. Table 10 gives the data on the

blowers that were collected.

22
Table 10. Evaluation of hand-held blowers collected.

No. Watts

App. age*

(years)

App . run

time (hrs .

)

Condition status*

1 950 1 100 Motor runs slower than it

should

2 400 old numerous Appears to run o.k.

3 440 old numerous Burning smell, heater not

working

4 440 old numerous Broken wire

5 275 old numerous Poor performance

6 215 15 780 Old

7 215 15 520 Old

8 215 6 150 Old

9 365 25 over 2000 Motor runs slow

10 200 7 150 Old

11 215 10 520 Excellent condition

12 215 old unknown Old

13 1000 2 70 Shorted coil

14 1000 1 1/2 60 Bad thermal element

15 1000 1/2 30 Bent shaft

16 ? 1 1 Fan blade loose

17 ? 3/4 65 Operating o.k.

*01d - indicates owner could not estimate age, however,

unit appeared to be over six years old.

Of the 17 hand-held blowers the wattage was recorded

for 15 of them. The average wattage was 452 and their

wattage could be broken down as follows.

Low Medium High

Wattage 215 or less 275-440 950 or higher

Number of

units 6 5 4

Because of the limited sample size the information can only

be used for guidance and should not be generalized for the

hair dryer population.

23
5. COMPUTATION OF LIFE CYCLE OWNERSHIP COSTS

The cost elements for hair dryers consist of purchase

price, energy cost and repair costs during the retention

period. A life cycle cost equation 6 for hair dryers

follows

N

LCC = P + I 1 r (EC). + (RC). 11 (DC)

t=l (l+i) r 1 r rJ (1+i)

where

,

LCC = present value of costs incurred during N years,

P = initial purchase price,

N = retention period,

i = discount rate (per year)

,

EC = energy cost,

RC = repair cost, and

DC = disposal cost. (This item becomes negative if a

consumer received money when disposing of an old

product .

)

Purchase price information is readily available to consumers

at point of sale. For the cost analysis a purchase price of

$20 was selected as a representative value for a 1000 watt

blow hair dryer.

Energy costs depend upon the input wattage and the

intensity of use for the dryers. The magnitude of the

energy cost expenditure would influence the importance in

providing consumers a means for estimating its value.

Because the recall survey responses exceeded the metered

values for each use intensity measure, the recalled

responses have been used to give an upper bound to the

energy cost values. Table 11 shows the average use

intensity values for the hair dryer users in this study.

6 Stiefel, s. W. , S. J. Kim and H. Hung, Life Cycle Costing:

An Assessment of Practicability for Consumer Products , NBSIR 77-1212, December 1976, p. 15.
The values were derived from the recall survey data in

Appendix B, table B-l. The estimated annual power

consumption, also shown in table 14, was approximately 30

kWh. The calculated electricity cost is $1.19 or $2.38 at

respective rate charges of $0. 04/kWh and $0. 08/kWh.

For this analysis the disposal cost (or salvage value)

was assumed negligible. This is reasonable considering the

ease for disposing of a small appliance and also the

difficulty in finding a purchaser for a used hair dryer.

Table 11. Computation of cost of energy.

Dryer Setting

High Medium Low Cool Total

Average # of hours

per dryer per year 20.4 9.9 2.8 1.3

Power input*

(watts) 1021.5 733.2 484.2 187 .

9

Annual kWh used 20.9 7.3 1.4 0.2 29.8

Annual cost ($)

@ $0. 04/kWh 0.84 0.29 0.06 0.01 $1.19

Annual cost ($)

@ $0. 08/kWh 1.67 0.58 0.11 0.02 $2.38

*Based on observations obtained from laboratory measurements

on 60 units at a supply voltage of 120 volts A.C.

Discussions with the repair agencies in the survey

indicated their approach in many instances was to offer new

units at a few dollars above cost when repairs exceeded

eight or nine dollars. Although many thousands of hair

dryers are repaired annually, there is evidence that the

vast majority of hair dryers are thrown away rather than

repaired. A yet to be published survey, sponsored by the

National Science Foundation at UCLA, dealing with small

appliance disposal, indicated that 78 percent of blow hair

dryers were replaced rather than repaired after failure.

25
More than half of the respondents said "that they would not

hesitate to throw away a product costing less than $20 if it

broke down." 7

One approach is to assume that hair dryers essentially

reach the end of their useful lives as soon as repairs are

required. Under this assumption no repair costs are

incurred during the hair dryer's useful life. A life cycle

performance test method which could predict mean time to

first failure would under this assumption also provide a useful life estimate.

If repairs and disposal cost are not included then the

ownership cost equation consists only of purchase price and

energy cost. It is possible to predict LCC values for many

different retention periods. In the absence of objective

results providing a useful life value, a series of LCC

values were computed for energy rates of $0. 04/kWh and

$0. 08/kWh and using discount rates of 0, 5 and 10 percent to

illustrate their effect on cost. These values have been

graphed in figure 4 for retention periods up to ten years.

Using the upper bounds of usage and energy cost, figure

4 indicates it takes approximately nine years for the energy

cost to equal the $20 initial purchase price. Of course,

using lower usage and energy rates and discounting future

costs further lowers the influence of energy costs. On the

other hand, doubling usage frequency would have the same

effect as doubling energy costs.

The value of figure 4 is in making comparisons with

alternative products to assess relative ownership costs.

Energy cost estimates for other blow hair dryers can be

derived from a combination of laboratory energy measurement,

field usage data and energy rate data similar to that

demonstrated by this project. To compare total ownership

cost for an extended period of time the "useful life"

estimate is needed. Dramatic differences in "useful life"

estimates for dryers of nearly equal purchase price would

result in a substantial difference in ownership costs. It

is possible to translate the cost data to an average annual

cost for the period corresponding to the useful life. The

average annual cost basis provides the means for comparing

products with different useful lives.

7 W. David Conn, "Factors Affecting Product Lifetime,"

27th Mechanical Failures Prevention Group Meeting, November

1977.

26
Figure 4. Average ownership cost for a 1000 watt

blow hair dryer (excluding repairs)

versus year of retention.

27
6 . CONCLUSIONS

This project provided the opportunity to test various

techniques to obtain information necessary for the

development of life cycle performance test methods and the

characterization of life cycle costs for a small appliance.

Appendix D summarizes the organizational structure used for

this project and the lessons learned which are applicable to

similar field studies.

A primary element of life cycle cost information is

usage data. Efforts to collect usage data involved both the

recall survey and instrumentation techniques. The

comparison of the results indicated a discrepancy between

results obtained by these methods. Therefore for an

accurate assessment of usage, data should be collected by

means of instruments (e.g., timers, counters, etc.).

However, since failures were found for several instruments

and feedback from users indicated inconvenience, specific

design and test criteria need to be addressed.

Instrumentation should be designed for and tested under

actual use conditions and should be configured to minimize

their effect on usage patterns.

Efforts to locate repair incidence, failure mode and

repair cost data involved a survey of repair firms, the

collection of used (usable and broken) dryers and field

testing under "normal" use conditions. The repair firm

survey results indicated that the most frequently repaired

components were heating elements, cords, fuses and switches.

Cleaning was also indicated as a frequent activity for

restoring units to use.

Collection of used hair dryers for analysis of hair

dryer condition and failures as a function of construction

and age provides some useful information, that allows

engineers to evaluate functioning and non-functioning units

and to collect through examination information on failed

components

.

The field testing experience indicated that extensive

monitoring time would be required to obtain repair incidence

and failure mode data under "normal" usage conditions.

Heavy commercial users could speed up the process. However,

they were not satisfied enough with the performance of the

study hair dryer to continue its use. Future experiments,

employing commercial firms to provide a heavy use test.

28
should select products which satisfy the requirements of the

commercial user.

Failure incidence data for small appliances are scarce,

difficult to obtain and may be misleading. Preliminary data

indicate that for inexpensive appliances, such as the handheld hair dryer, most units are discarded when they need

repair. Therefore, repair data obtained from repair firms

and even from manufacturers would underestimate failure

rates and may not be representative of failure modes.

Because of the implications of this finding additional

research to confirm the "throw away" approach to relatively

inexpensive appliances is warranted. If products are

generally not repaired then a laboratory test which succeeds

in predicting mean time to first failure would also provide

a reasonable useful life estimate. The laboratory test must

stress all components likely to fail. To translate the

laboratory result into a meaningful value for consumers

requires the integration of usage information. This is

necessary both to guide in the selection of the laboratory

usage cycle and to relate mean operating usage cycles to

mean calendar time.

Life cycle costing analyses were performed using the

usage patterns derived from this study. Under the

assumption that hair dryers essentially reach the end of

their useful lives as soon as repairs are required, no

repair costs were included in the analyses. Disposal cost

was also considered to be negligible. The two cost elements

remaining were initial purchase price and energy cost. In

the absence of objective results providing useful life

estimates, a series of ownership cost values were computed

for energy rates of $0. 04/kWh and $0. 08/kWh and using

discount rates of 0, 5 and 10 percent to indicate their

influence on cost. Using the upper bounds of usage and

energy cost, it takes approximately nine years for the

energy cost to equal a $20 initial purchase price. Of

course, using lower energy rates and discounting future

costs further lowers the influence of energy costs. The

value of LCC is in making comparisons among alternative

products to assess their relative ownership costs. LCC

comparisons for hair dryers would include factors for useful

life, purchase price and energy costs in making comparisons

on an annualized basis. Annualizing costs permits

comparison of products with different useful life values

over a similar time period.

29
APPENDIX A. ANALYSIS OF SAMPLE SIZE FOR HAIR

DRYER EXPERIMENT

Problem: Compute the sample size required to ascertain the

mean (m) failure time for the field study of hair dryers with

a risk (a) that the estimate of m is off by d or more hours.

Preliminary laboratory tests on 15 hair dryers yielded

estimates for time to failure. The mean failure time was

178.6 hours with a standard deviation of 41.6 hours. In order

to determine sample size, estimates of the population standard

deviation (a) are required. Assuming the laboratory data

provides a best guess concerning results expected in field

testing, the standard deviation of 41.6 hours can be used to

estimate a. Let d = 10 hours

a = .05

According to NBS Handbook 91* the first estimate of the

total sample size required (n 1 ) can be computed as follows:

Z

( l-a/2

)

a

where, z = the z statistic from tables

n ' = (1.960) (41.6)

10

= 66.5.

A rough rule, according to NBS Handbook 91, is to make

the first sample greater than or equal to 30 unless the computed

sample size is less than 60. An initial sample size (n^) of 30

units was selected for the field study.

The 30 units are undergoing field use. Once the failure

data are obtained, the estimate of the population standard

deviation (s^) computed from these units can be used to

determine how large the second sample should be. The second

sample ( n^ ) is computed as follows:

*Mary Natrella, Experimental Statistics, National Bureau of

Standards, Handbook 91, October 1966, p. 2-11.

30
where, t =

n =

therefore

,

n (i-g/2)

d

student's t statistic from tables for n^-1 degrees

of freedom

the total sample size for the first and second

samples combined

n^ = n-n^.

31
APPENDIX B. USAGE DATA SUMMARY

The tables in this appendix consist of summary data

obtained from responses to the recall survey and obtained from

each dryer's instrument readings for use hours and on-off

counts. Table B-l provides the recall usage data by

participant for each hair dryer. Tables B-2 , B-3 and B-4

summarize personal information pertaining to age, hair

characteristics and room of use. Table B-5 contains

instrument readings for hours used and on-off counts.

32
Table

B

-1

.

Questionnaire

raw

usage

o

o

o

rzi.

{/) QJ (D (A S & JJI

u&

M , a

U 4J 3 cr> q c 53 «.s

(U t> u s InlH 1/1 ? u

3

-a l\

i o o

00in

si R'

in

<N O

o

C\ o o o o

cn in o

4-1 U) ??

5 &a

in

ro &

8

f—I r—

I

U QJ 8.1 o in m o CO rH rH m

i ro

in <n o ^ l I o

ro oo ro

W

^ Oj J-i - Si 8-

o

rH

I rO(N(Nh>MfOin t CN ro tD ro m r- co i ri ^ fN

o in

r- m o o in m

o o 00 rH o oo

o in o 0(^0 o o •H O

P'o

d 6

in in fNrHCNinm^HrHCNrO ro rH rH O iH rH rH (N CN rH tH

R§

in o in o o CO r—1 <N i—I 00 f—I ro oir-ninor— imooiniiniinminininoiinir-inieNinioo i in —i r-i m <M .h in m iHo rH r-i

'—I r—I <—t CM sl ro m ro o fN ro o <n <n

<N

<N \ O

I rH ro |

i—I 00

rr ro in r- r- rro

ro ro in l I h* <D CN rH

(/) >i m h*

lD ^j-covn^rcNH'incTiroinLninroorHrorNr-corsimcNr-OfHo vD'iO'^omiDmtovni£>vx)iD*sOvDr^oo to lOvoinuo^riovo^o^oiD

inv£)r^oo<T>o^HCNroH, iniDr^ooaNOfHCNroH, iniDr^oo<T»o r\irNjrsjrsiOsirorororororororororoH, H'H, H’H*^H*H, ^r^rLn

33
Table B-2. Sex and age of NBS hair dryer participants.

Under

10 years

10-15

years

16-21

years

Over 21

years Totals Percentage

Male 0 2 5 18 25 37%

Female 2 8 15 18 43 63%

Totals 2 10 20 36 68

Percentage 3% 15% 29% 53%

Table B-3. Hair length and thickness of

NBS hair dryer participants.*

Short

Collar

length

Shoulder

length

Longer than

shoulder Totals

Thick 7 12 3 1 23

Medium 15 14 4 3 36

Thin 4 3 1 1 9

Totals 26 29 8 5 68

*Participants use<

characteristics

.

d their owin perception s for describing hair

34
Table B-4. Room most often used to dry hair

by NBS hair dryer participants.

Number Percentage

Bathroom 44 65

Bedroom 22 32

Living room 1 1

Family room 1 1

Totals 68

35
Table B-5. Meter readings raw data.

Dryer no.

Days

used

Hours

used

On-off

counts

21 65 2 25

22 64 2 85

23 57 1 40

24 70 2 40

25 64 4 105

26 68 5 45

27 66 4 170

28 64 6 375

29 62 5 150

30 64 4 45

31 65 6 no reading

32 69 4 105

33 63 no reading* 90

34 65 4 80

35 65 6 175

36 65 4 75

37 63 no reading 175

38 70 3 50

39 81 6 135

40 63 4 75

41 62 4 165

42 67 4.5 50

43 58 5 100

44 62 no reading 140

45 46 1 no reading

46 62 3 50

47 67 4 95

48 60 no reading 80

49 61 no reading 50

50 60 8 150

*No reading indicates meter readings could not be taken

due to damaged instruments.

36
APPENDIX C. COMPARISON OF USAGE VALUES FOR

SURVEY RESPONSE AND METER ESTIMATES

Comparison of the recall survey response with the metered

values required computation of compatible values. Comparisons

were made between survey and metered estimates for the hours

of operation, total on-off cycles and minutes per on-off

cycle. Distributions for estimates of accumulated hours per

dryer, on-off cycles per dryer and minutes per on-off cycle

comparing the metered and questionnaire survey responses are

shown in figures C-l, C-2 and C-3. Values were either taken

directly from the raw data or calculated as shown in table C.

An explanation of how each of the calculated values in table C

were derived, identified by column number, follows.

Column 2 - Recall hours of operation

Hours of operation = days used x

^loa -LS week

x =—= x

60 min 7 days

N

Z User i=l

uses ,

. > mm ,. . (l) x ——(l) week use

Column 3 - Recall on-off counts

W00 uses On-off counts = days used x 3 x ^ , 1 daysJ

. . week

user i=l

N

Z (i) x

on-off cycles

use

(i)

Column 4 - Recall minutes per on-off cycle

min

N

Z user i=l

Minutes per on-off cycle =

use

(i)

on-off cycles (i)

use

uses . . > min , .

.

x -tttt(i) x ——( 1 ) week use

N

Z user i=l

uses , . . mm , .

,

(1) x —(1) week use

Column 5 - Metered minutes per on-off cycle

Minutes per on-off cycle hours used 60 min

on-off counts hour

37
> Survey response? Accum. hours per dryer

y Metered resposns? Accum. hours per dryer

Figure C-l. Accumulated hours per dryer.

38
6

> Survey Response? On-off cycles per dryer

>

F requency

Metered response? On-off cycles per dryer

Figure C-2. On-off cycles per dryer.

39
8

F requency

i T" I ' T 1 "I"T

" *

1 -30 -20 -10

Survey Response:

— r*-rl ^ i

' r

1 ^

i i

, "i~i ^ ~ r r: i 0 10 20 30 40 50

flinutes per on-off cycle

>

F r «q vancy

Pletered response; Minutes per on-off cycle

Figure C-3. Minutes per on-off cycle.

40
Table C. Calculated usage values.

Dryer

no.

Recalled Estimates

Metered minutes

per on-off cycle

Hours of

operation

On-off

counts

Minutes per

on-off cycle

21 8 209 2.7 4.8

22 1 55 1.0 1.4

23 2 86 1.4 1.5

24 23 185 7.5 3.0

25 14 229 4.5 2.3

26 8 49 11.7 6.7

27 18 219 4.9 1.4

28 34 727 2.8 1.0

29 21 771 2.1 2.0

30 5 37 8.3 5.3

31 21 93 13.9 * 32 15 99 9.4 2.3

33 6 184 2.2 —

34 24 181 9.6 3.0

35 6 237 1.7 2.1

36 4 102 2.5 3. 2

37 17 270 5.0 —

38 5 no response — 3.6

39 17 272 4.1 2.7

40 36 270 8.1 3.2

41 8 894 1.0 1.5

42 7 96 4.6 5.4

43 14 99 8.7 3.0

44 13 133 6.4 —

45 13 72 11.3 —

46 18 71 15.1 3.6

47 3 144 1.1 2.5

48 18 146 7.6 —

4 9 3 39 5.1 —

50 20 120 10.0 3.2

*Dashed lines indicate meter readings could not be taken due

to damaged instruments.

41
APPENDIX D. IMPLICATIONS FOR FUTURE FIELD STUDIES

D . 1 Organizational Structure

Designing, planning and implementing field studies

requires organization. The organizational structure used in

this field study is depicted by the flow diagram shown in

figure D. Of course, every individual study may vary but

the sequence and stages will be similar. Phase I involves

translation from a set of objectives for a given consumer

product through the planning of a field study design. Phase

II incorporates the processes of obtaining approvals,

instrumentation development, functional and safety testing,

participant location, etc., required prior to Phase III

implementation of the field experiment. Phase III includes

pilot and pretesting of measurement instruments and

questionnaires to insure any unforeseen problems are solved

prior to implementation of the field study followed by the

experimental part of the study. Phase IV involves analysis

of data collected in order to translate it into the

informational elements required and identified by the

original project objectives.

D . 2 Lessons Learned

D.2.1 Allocation of Time

Field studies are time consuming. Lead time must be

allotted to allow for the various approvals, e.g., the NBS

Human Research Ethics Committee and/or OMB, or to design,

produce and test necessary measurement instrumentation.

The hair dryers remain in field use, although the data

shown in this report constituted use periods of only 8 to 11

weeks. The expected usage pattern of the product under study

and the project objectives should control the period

allotted for deployment of products in the field. Usage

data can be obtained with shorter deployment times than

failure data. The combination of usage data with failure

data is the ideal and is not available without monitoring

field use experience.

D.2.2 Participant Selection

Finding willing participants can be a difficult and

tedious process. Several advertising campaigns should be

planned and attempted. More volunteers than eventually are

needed should be solicited so a choice of participants is

42
PHASE I. FIELD STUDY DESIGN PHASE II. PREPARATIONAL

Design

questionnaire

Pretest questionnaire

Prepare CMB o r GSA approval,

if necessary

Define Preliminary

. requirements data analysis

Identify

data collection

methods

Select number of appliances

Procure appliances

Design functional

tests of

appliance

Design and construct measurement instru

ment package

Perform

functional

tests of

appliance

Design and perform test of measurement

instrument

make and

model of

1 appliance

Advertise and locate potential

study participants

Prescreen Select participants ~*| Participants

Obtain signed participant

agreement

forms

Prepare and submit Human Ethics Committee report

PHASE III. IMPLEMENTATION PHASE IV. ANALYSIS

Figure

for

D. Organizational structure

conducting field studies.

43
available at the time of selection. If a statistically

representative sample is required the preliminary

questionnaire designed for this field study should be

expanded to include more in-depth information so participant

selection can be made smoothly.

Attempts to utilize "heavy" users in order to shorten

the expected time to failure proved unproductive. In our

field study the hair dryers were rejected by hair cutting

salons, following a trial period, because their heat output

was inadequate and the measurement instruments inconvenient.

Therefore, if the product being tested, which is suitable

for a typical consumer, does not meet the requirements of

the commercial "heavy" user, participants will be difficult

to find. A second consideration when utilizing "heavy"

users involves the type of use. If usage is substantially

similar, only more frequent, higher failure rates can be

translated to "normal" use. Failures caused by additional

abuse or overloading, however, must be avoided.

D.2.3 Instrumentation for Data Collection

The comparison of the results from the recalled survey

with the results from instruments measuring time and on-off

counts pointed out a large deviation. Reliance on recalled

estimates may be misleading. In addition to accuracy

questions, volunteers are usually not willing to spend

extensive periods of time answering questions about

appliance usage; therefore the questionnaire should be

limited to significant questions that can be answered

quickly and easily.

No relationship between the metered and recalled values

could be established. This lack of agreement points out the

importance of using reliable instruments to draw valid

conclusions. As much as possible of the data should be

collected by means of timers, counters, etc.

Questionnaire development is one of the most intricate

parts of the data collection. Before questions are written

it is necessary to decide exactly what information is

required. Wording of the questions also demands great care.

The large discrepancies between the recalled data and

measured values leaves some unanswered questions. Since

both are estimates of the actual usage, it is highly

desirable to be able to place confidence limits around them.

44
Internal instrumentation of the hair dryer circuitry

was considered as an alternative to the external package

attached to the power cord. Several considerations resulted

in elimination of the internal instrumentation option

including possible invalidation of the manufacturer's

liability and modification of the hair dryer configuration

which could result in changed performance.

Measurement instruments should be designed and tested

with the field environment in mind. Five out of the 30

measurement units were damaged and could not be read.

Although participants were asked to report dropping or other

damage of the instruments, only one such case was reported.

The measurement instruments should be tested for their

accuracy, reliability and resistance to expected

environmental effects, such as shock. If possible a set of

products should be designated for control, equipped with

both the measurement instruments and a control device such

as a conventional timer and counter.

A secondary effect was observed for the measurement

boxes attached to the hair dryers. During this study it was

discovered that several participants considered the

measurement boxes inconvenient, therefore it is possible

that use patterns were changed. It would be difficult to

determine to what extent these complaints affected dryer

usage.

The hair salons were a particularly interesting case.

They not only found the black box inconvenient, but they

stated that they did not have the space to plug in the dryer

because of the box size. Space was often very tight in

beauty salon outlets because so many other appliances such

as curling irons were also plugged in the same wall sockets

as the hair dryers.

D.2.4 Failure Data Collection

The identification of failure modes was accomplished

using both collection of used hair dryers and survey of

repair agencies. The field study has only resulted in a single failure during the few months it has been in

progress. Failure rate data, however, was not found during

the course of this study.

Some of the individuals, which contributed failed hair

dryers still under warranty, did not want to be troubled by

the nuisance, delay and expense involved with getting a

45
repair. If such an attitude is pervasive, feedback of

failure rate data to manufacturers may be incomplete even

during warranty periods. Many persons view the hair dryer

as a relatively inexpensive appliance which they perceive as

economically unrepairable. It is expected that although

many thousand hair dryers are repaired, the majority are

discarded. Small inexpensive (less than $25) products like

the hair dryer probably follow a similar pattern. This

implies failure rate data from user experience or repair

agencies will be very difficult to obtain, or may be

misleading. Laboratory test methods, based upon controlled

field experiments, may be the only means for obtaining useful

life estimates for these small appliances.

46
NBS-1 14A (RCV. U-77)

U.S. OEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 78-1500

2. Gov’t Accession

No.

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE 5. Publication Date Application of Life Cycle Costing to Hand-Held

Hair Dryers: A Field Demonstration for Small Appliances 6. Performing Organization Code

7. AUTHOR(S) , , . „ . „ „ . S. Wayne Stiefel, P. Clare Goodman and William B. Berne

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4411135

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as item 9

13. Type of Report & Period

Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

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

bibliography or literature survey, mention it here.)

This report describes a demonstration project on hair dryers which applied the

life cycle costing technique to a small appliance where the consumer is a significant

factor in its usage. Described are the field data collection techniques: including

an experiment to collect use, energy consumption and repair data from participants

provided with specially instrumented hair dryers. Repair and repair cost data were

also obtained from collecting used hair dryers for failure mode analysis and from

repair agency surveys.

The lessons learned provide insights into the application of the life cycle

costing technique to other small appliances. This study indicated individualsr recalled

estimates for usage significantly exceed the metered values. It is important, therefore, that measurement instruments be used as much as possible to collect usage data.

The importance of developing test methods based upon controlled field use experience

was in part substantiated by the inability to obtain failure rate data. Some of the

individuals who contributed failed hair dryers still under warranty did not want to be

troubled by the nuisance, delay and expense involved with obtaining a repair. If such

an attitude is pervasive, feedback of failure rate data for inexpensive appliances

may be incomplete even during warranty periods.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Field data collection techniques; hair dryers; instrumented usage data; life cycle

costing; repair data; small appliances.

18. AVAILABILITY jXX Unlimited

c For Official Distribution. Do Not Release to NTIS

[

I Order From Sup. of Doc., U.S. Government Printing Office Washington, D.C. 20402, SD Stock No. SNOOjgg?

Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

52

22. Price

$5.25

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