3021_07 Allowances Practice Problems

8/11/2019 3021_07 Allowances Practice Problems

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Allowances

Practice Problems


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Example 1

Suppose you have a fine assembly task Standing

Requires approximately 300 kCal / hr (based on

HR measurement) NT = 90 cmin.

Additional Considerations include Illumination25 fc in work area

Noisefairly continuous 91 dBA in work area

HeatFirst hot day of the year, WBGT = 80 F No significant mental strain, monotony, or

repetitiveness.

What is the Standard Time?


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Example 1 (contd)

ST = NT (1+ allowances)

2 ways to find allowances

Quick & Dirty way Table 11-2 (ILO Recommendations)

More thorough way

Calculate individual relaxation allowances,RA, for each variable and special allowance

factor.


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ILO Recommendations

Table 11-2, Niebel & Frievalds p. 437


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Example 1 (contd)

More thorough method Use Table 11-11, p. 453.

Some factors can be found directlyfrom the table

Constant

Posture

Visual Strain

Others must be calculated.


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Example 1 (contd)

Personal needs = 5% (always constant)

Basic Fatigue = 4% (always constant

Posturestanding = 2% Why isnt there an option for seated?

Visual StrainFine assembly = 2%

Mental Stress, Monotony, Repetitiveness =

0%.


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Example 1 (contd)

Illumination

Looks like a chart lookup, but what are

IES subcategories? Refer to Ch. 6, p. 237, Table 6-2.

Our illumination = 25 fc, or CAT D.

What should our illumination category be?

Do you see fine assembly listed? Should be between medium & extra-fine

assembly.

Should be CAT F, but we are 2 categories below.

From Table 11-11, illumination allowance = 3%


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Example 1 (contd)

Atmospheric Conditions (HEAT)

Workload, W = 300 kcal/hr

WBGT = 80 F

How do you determine WBGT?

RA = e (-41.5 + 0.0161W + 0.497WBGT)

= e (-41.5 + 0.0161x300 + 0.497x80)

= e(3.09)

= 22% Can also lookup RAL from Fig 6-11, p. 253.

RAL for 300 kcal/hr & WBGT = 80 F is 48 min/hr

12 min rest / 48 min work = 25% allowance.


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Example 1(contd)

Noise SPL = 91 dBA

What is SPL

Need to calculate dose for 8 hour day. If 90 dBA is 8 hour-100% dose, what about 91dBA?

Must find time for 100% dose T = 8 / 2 [(L-90)/5]

T = 8 / 2 [(91-90)/5].

T = 6.96 hours is a 100% dose for 91 dBA.

D = 8/6.96 = 1.15.

RA = 100 x (D1)

= 100 x (1.15-1)

RA = 15%


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Example 1 (contd)

Find Standard Time

ST = NT x (1 + allowances)

ST = 90 cmin x (1+0.05+0.04+0.02+0.03+0.02+0.22+0.15)

ST = 90 cmin x (1 + 0.16 + 0.22 + 0.15) HEAT NOISE

ST = 90 x (1.53)

ST = 137.7 cmin


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Example 1 - Redesign

As a process engineer, what would be

the first things you would want to do

to bring the standard time closer tothe NT?

The heat allowance is the largest?

It can be reduced to eliminate extra heat

fatigue.

How?

The noise allowance is the next largest

What would you do about that one?


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Measurement

How do you measure Illumination?

Heat?

Noise? For the next 3 labs, you will practice

measuring these three environmental factors This week, we will begin with noise.

You will write one report that considers theimpact of these three factors on workperformance based on the data you will collect

AND, based on some homework problems you

will receive in lab.


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Homework

Work the following problems

Ch. 11Prob #1, 2, 3, 5 & 7.

Due one week from today.

This is in addition to the homework

you will receive in lab today!! But, theres no report due next week.

3021_07 Allowances Practice Problems

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