Environment and human experiment experiment 1 2 3 – group 6

Department of Manufacturing Engineering Experiment on Measuring Illuminance " z- the ratio between the average illuminance Etb and Enin.. Practice measuring illuminance: with the availab

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Department of Manufacturing Engineering Experiment on Measuring Illuminance

HO CHI MINH CITY NATIONAL UNIVERSITY

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY FACULTY OF MECHANICAL OF ENGINEERING

Ho Chi Minh City, May 8", 2024

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EXPERIMENT 1 MEASURING ILLUMINANCE OF CLASSROOM

I Purpose:

- Know how to use the light meter C.A 811 to measure illuminance

- Compare the measured results with theoretical calculations

- Evaluation of experimental results

II Requirements

- Read the experiment guide before the experiment

- Calculate the average theoretical illuminance (Etblt) of the classroom by using the utilization factor method

- Measure the average illuminance (Etbd) of the classroom by using light meter

- Compare the calculated result (Etblt) with the measured result (Etbd)

- Evaluate experimental results

S - area of illuminated classroom (m’)

a, b - classroom length, width respectively (m)

Hcis the distance from table surface to lamp (m)

From the above calculated classroom index 1, we search for the value of the utilization factor (see Table 9-12, page 158 in textbook “Labor Protection Engineering” by Nguyen Ba Dung and other authors - 1979)

Fori <=0.8, h=0.05-0.36

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" z- the ratio between the average illuminance Etb and Enin z = Etb/Emin (usually z

= 1.1 - 1.2 If classroom is smaller than 10 m? then z=1)

" S— classroom area (m’)

" h- utilization factor

- Calculating the number of needed illuminating lamps (Nbd)

Let the luminous flux of a lamp be @a, we can calculate the number of needed illuminating lamps Nbd:

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TIL.2.1 Introducing light meter C.A 811

1.2.2 The EXTECH — EasyView EA30 light meter is equipped with a silicon screen, digital display, and easy manual operation due to its compact size

III.2.3 Working principle (see picture)

IH.2.4 » Compact and ruggecd design features large display

IH.2.5 > Multiple wide measuring ranges:

IHI.2.6 Model EA30 - 40,000Fc in 4 ranges and 400,000Lux in 5 ranges

11.2.7 Model EA31 - 20,000Fc in 4 ranges and 20,000Lux in 4 ranges

IH.2.8 + Data hold freezes reading on display

HI.2.9 |» MIN/MAX readings

IH.2.10 > Cosine and color corrected measurements

IH.2.11 + Low battery and overrange indication

IH.2.12 » Auto power off to save battery life

IH.2.13 +» Utilizes precision silicon photodiode sensor with 3ft coiled cable for easy

storage

HH.2.14 »* Complete with built-in stand, remote sensor with protective cover,

protective rubber holster, and 6 AAA batteries

HL2.15 Usage:

Process:

1 Place the sensor on the surface to be measured, avoiding any shaded area so as

to not affect the measurement results

2 Turn on the meter switch, select one of the two lux or fc units When the

measured value is displayed on the screen, wait until the value is stable

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3 Record the measured value when it is stable, then turn off the sensor and move

to the next point

Measurement range: 20 lux; 200 lux; 2000 lux; 20 klux

20 fc; 200 fc; 2000 fc; 20 kfc

Measurement value: 0.01 lux; 0.01 fc Accuracy:+ 3%

III.3 Experiment practice:

HH.3.1 Task:

1 Calculate theoretical classroom illuminance: determine the necessary parameters

of the classroom to measure the illuminance (length a, width b, height H, height of the lamp compared to work surface He, distance from lamp to ceiling he)

Look up the necessary values such as: Emin, Emax, reserve factor k, lamp type, Calculate the number of lights needed Nbd, distribute the lights, calculate the theoretical brightness Etblt,

2 Practice measuring illuminance: with the available light distribution m the classroom, the illuminance E is measured at several points on the working surface, calculating the average illuminance level in cases:

a Natural light and bulb light

b No light

3 Compare the calculated Etblt with the actually measured Etbd

IIf.3.2 Experiment process:

1 Determine the necessary parameters of the classroom

2 Determine the points to be measured the illuminance of the classroom (note the special points such as the brightest point, the darkest pomt, .)

3 Measure the illuminance at selected points in both cases with and without the electrical light Record measured results

4 Report results of the experiment in the form

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REPORT

I Calculate the theoretical average illuminance:

1 Determine the parameters of the classroom

Classroom length: a= 11 (m); Width:b=6 (m)

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Measurement area with lights off

2 Determine the required data: [luminance (E); Reserve factor (k); The ratio between the illuminance level Etb and E min (z) (usually select z= 1.1 to 1.2); Classroom index (1

- calculated according to Equation 3.1); Utilization factor h

IIllumimanee: E = Enin= 300 lux

Reserve factor: k = |

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Ratio between illuminance levels: z= 1.2

Classroom 1ndex: H-(b+a) 2.5(6+11)

Choose utilization factor: h = 9.08

3 Calculate the Etblt luminance using the utilization factor

- Calculate the total luminous flux of the lamps f; according to Equation3.2

— Emn'K*Z'Š _ 300-1-1.2:66

- Determine the number of needed lamps Nbd to illuminate the classroom according to Equation 3.3

In this experiment we choose the type of lamps: fluorescent lamp 6,500 K, power: p

= 36 W with the luminous flux of the lamp @pa= 2,500 Im

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II Measure the illuminance of some points in the classroom

1 Case 1: Natural light and electrical light

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III Comparing theoretical Etb and actually measured Etb

Theoretical Etb is higher than both actually measured Etb Both acutally measured Etb is

<300 lux while the theoretical Etb is 360, well over 300

IV Evaluating experimental results

- Does the level of illuminance in the classroom meet the state regulations?

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Department of Manufacturing Engineering Experiment on Measuring Illuminance The state regulations stipulate that the illuminance level in the classroom should fall within the range of 300-500 lux, yet the measured data fails to meet this requirement This discrepancy may be attributed to non-functional lamps in the room, which do not provide sufficient light, thus compromising the accuracy of the light meter This could occur due to faulty bulbs, or 1t might be a result of inaccurate or insufficient installation

of lamps to ensure uniform illumination throughout the room

Broken bulb

- Does the lighting conform to lighting techniques (even illuminance distribution, not too bright, not shady, .)?

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Department of Manufacturing Engineering Experiment on Measuring Illuminance The lighting in the room does not ensure specific lighting techniques The luminance distribution on the surface is uneven, which can be seen through the results of measuring the illuminance at 14 points in the classroom, creating black shadows at some points

Measurement area when all lights are turned on

- Comments and personal suggestions on lighting techniques in the classroom?

Consider the theoretical illuminance value of 360 lux and the actual illuminance after measurement is 260.93 lux with 12 light bulbs (and 2 broken bulbs) Using the three- power method, we can deduce that the number of light bulbs needed to install in the room is about 16 light bulbs

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EXPERIMENT 2 MEASURING NOISE LEVEL

I OBJECTIVES

- Help students familiarize themselves with the NL-20 handheld noise meter

- Know how to set up position, measurement points, record the data and process the

measurement results

- Give individual or group comments, opinions on the status of noise pollution, propose specific measures to reduce noise

IL CONTENTS

As guided by the instructor, groups of students will observe, record, measure noise level

caused by the noise source, draw the noise level curve based on measured and calculated data,

then give comments

ACCORDING TO DISTANCE

If the typical noise level of the noise source (usually measured at a height of 1.5 m) is ata known distance rl from the noise source (r1 is usually equal to 1 m for noise from industrial machinery and equipment, and is equal to 7.5 m for noise sources from traffic vehicles), the noise level at a distance r2 from the noise source will be less than the noise level at the distance with rl and is determined according to the following formula:

¢ For point sources:

Where a is the noise absorption coefficient of terrain:

- For asphalt and concrete surfaces: a =- 0.1

- For empty land without tree: a = 0

- For arable land: a= 0.1

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IV RION NL-20 METER

Fig 1: Handheld noise meter NL-20

Fig.2: Functional buttons Fig.3: How to hold the meter

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* Introducing functional buttons:

Store Store measured data into memory

Mode Used to read measured results Each time this button is pressed, the screen

changes the measurement result display mode in memory

Pause/Cont During measurement, this button can be used to pause the measurement

process to remove unwanted values

Menu When this button is selected, a 1/3 menu will be displayed and allow to set

options, which can be switched between three different menus by pressing the

A/C/FLAT Set the frequency to A, C or FLAT

Fast/Slow Set the measuring time to Fast or Slow

Range Select the measuring range of the device There are six different options: 20 to

80, 20 to 90, 20 to 100, 20 to 110, 30 to 120, 40 to 130

Recall Used to review data stored in memory

Recall Data Used to switch between different values stored in memory

Light Used to turn on / off the backlight to support reading data without light

data will be printed when this button is pressed

Cal Used to activate calibration mode

Power Used to turn the meter on/ off for more than 1 second

Note: The strap is worn as shown in figure 3 to avoid dropping the meter

Guide for measurement:

Step 1: Hold down the Power button for more than | second to open the meter

Step 2: (Used in low light) Press the Light button to open the lamp of display screen

button, to select "Fast" and press Range button to select the appropriate measurement range

Step 4: The device is ready, can be used in the experiment

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Department of Manufacturing Engineering Experiment on Measuring Illuminance Step 5: After the experiment, hold down the Power button for more than 1 second to turn off the

meter

Measure the noise level, calculate and draw the noise level curve at a noise source point:

V.1 Select a noise point source which is a machine tool or an operating machine, equipment that is creating noise

V.2 Place or hold the meter at a height of 1.5 m away from the center of the noise source, put

the microphone in direction of the center of the noise source, measure the noise level (measured

in decibels - dB) and record the measured values (see the experimental equipment section to know how to manipulate) Only read round numbers to dB, no need to read odd numbers Every second read the number in syne with your breathing When encountering unusual numbers such

as too large, then ignore to make data processing be favorable Read and record approximately 30 values per measurement into the following tables

A, Recording noise level in C1 workshop

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Table 1: Record measured data at a distance of I meter from noise source

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Department of Manufacturing Engineering Experiment on Measuring [luminance

1) Calculate the mean value of the measured results from Table 1: 60.6 (dB)

2) Move the meter away from the noise source by 3m, then measure and record

continuously 30 values into Table 2

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Table 2: Record measured data at a distance of 3 meter from noise source

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1) Calculate the mean value of the measured results from Table 2: 57.5 (dB)

2) Calculate the noise reduction calculated according to formula (1):

3

1

3) Determine the calculated noise level using the formula:

6,=L, — L,= 60.6 — 10.3 = 50.3 (dB) Hint: The noise level calculated according to the formula at the distance of 3m = the average value from Table I (at a distance of Im) - the noise reduction calculated according to the formula at the position of 3 m compared to I m

For example: the mean value of the measured result from Table I is 90 dB, the noise

reduction by formula (1) is calculated as 20 dB, the noise value calculated by the formula

is: 90 dB - 20 dB = 70 aB

4) Take the meter away from the 5 m noise source, then measure and record continuously

30 values into Table 3

Tiêu đề	Experiment on Measuring Illuminance
Tác giả	Nguyờn Trung Sơn, Trõn Tuần Anh, Phựng Sở Nam
Người hướng dẫn	Ms. Dương Huyền Lynh
Trường học	Ho Chi Minh City University of Technology
Chuyên ngành	Manufacturing Engineering
Thể loại	experiment
Năm xuất bản	2024
Thành phố	Ho Chi Minh City

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