ILLUMINATION and SOUND

ILLUMINATION and SOUND

ILLUMINATION

   Causes of Poor Lighting

There are several causes of poor lighting namely:

1.      Flickering tubes

2.   Misadjusted reflectors

3.    Installation within the line of vision

4.   Poor maintenance

5.   Operation outside of rated voltage

6.    Lack of uniformity

7.    Shadows or spotty illumination

8.    Inadequate amount of light

   Fluorescent Lighting

Fluorescent lighting features that help prevent accidents are:

1.      Higher overall efficiency, which encourages more adequate lighting

2.   Improved quality of light more closely approaching daylight

3.    Less sensitive to voltage fluctuations, which tend to decrease eyestrain

4.   Lower temperature which gives more comfort to persons working close to light source

   Illumination and Accident Prevention

The sense of sight is produced by the coordination of two factors:

ž Physiological factor, the eye. In case of faulty vision, the control is limited almost exclusively to supplying artificial lenses, known as "glasses" to assist the natural lenses of the eye to focus light rays on the retina.

ž External factor is radiant energy, natural or artificial, within the visible range that is light combination which the brain can transform into the sensation of sight.

Four fundamental factors involved in the ability to see:

1.      The size of the object

2.   Contrast is defined as the difference in the reflecting qualities of the object and its background.

3.    Brightness

4.   Duration of exposure

       Any violation of the fundamental rules of good illumination will have an adverse effect upon the ability to see, as it will handicap the action of the eye. This usually involves a time elements because whenever there is insufficient light more time is needed to see clearly than is required when lighting is good.

   Glare

Glare is defined as a bright and dazzling light which has a blinding effect on the eyes. This is the most important single condition that adversely affects the ability to see.

   Natural Lighting of Buildings

Daylight illumination of factories supports the slogan: CONSERVE ENERGY. In order to use daylight to advantage, various design factors must be taken into account.

These include the following:

ž Variation in the amount and direction of incident daylight

ž Luminance (Photometric brightness) and luminance distribution of clear, partly cloudy, and overcast skies

ž Variations in sunlight intensity and direction

ž Effect of local terrain, landscaping, and nearby buildings on the available light

The various schemes are as follows:

ž Sidelighting

the placement of fenestrations on the lateral sides of the building.

ž Toplighting

the placement of fenestrations on rooftops.

Industrial Facility

Lighting Intensity

1. Hangars     Shops and service areas 2. Garage     Repair and wash     Storage area     Service area     Basement and pipe spaces 3. Laundries     Work area 4. Shops     Fine     Medium     Rough 5. warehouses     Active storage     Refrigerated storage     Work areas, crating and packing     Dead storage 6. Miscellaneous     Locker rooms     Mechanical room     Generator room     Toilet and washroom     Utility and storeroom     Loading platform     Stock room 7. Administration Building     Conference Room and Executive     Intermittent desk work     Prolonged close work     Drafting, computing, processing     Lobby     Corridor-hallway 8. Cafeteria     Dining room     Kitchen 9. Clinic     Examination room     Treatment

25 foot-candles 25 foot-candles 10 foot-candles 20 foot-candles 5 foot-candles 20 foot-candles 30 foot-candles 20 foot-candles 10 foot-candles 5 foot-candles 5 foot-candles 15 foot-candles 3 foot-candles 10 foot-candles 10 foot-candles 10 foot-candles 10 foot-candles 5 foot-candles 5 foot-candles 5 foot-candles 25 foot-candles 20 foot-candles 50 foot-candles 50 foot-candles 10 foot-candles 5 foot-candles 10 foot-candles 20 foot-candles 30 foot-candles 30 foot-candles

Sound

Sound waves – 1120 ft. per sec. or 763 miles per hr.

Frequency – the number of cycles performed in 1sec.

Intensity – the amount of energy obtained in the vibrating air particles is the intensity of a sound wave.

             –The wider the amplitude

of vibration, the greater is the intensity.

             – The greater the intensity, the louder the sound.

Decibels (db) – the intensity of sound is measured in terms of a unit measure called decibels (db).

Noise – any undesirable sound.

The measurement of any sound stimulus is commonly made with a sound-level motor composed of a microphone and associated electronic equipment.

Analyzer – is an electronic device for separating the noise into its tonal components, or into group of components. The results of measurement are given in decibels (db), which is called the sound pressure level.

Sound pressure level= 20 log (n/0.0002 dyne per cm2)

where: n= sound pressure in the air.

Outdoors, the sound levels decrease 6db each time the distance between the source and the microphone is doubled. Conversely, the sound increases 6db each time the distance is halved. Indoors, the acoustic of the room greatly modifies this rule.

Sound Intensity – The intensity of the sound source may be indicated by the total power in watts that it produces in the air around it.

3 classes of sound:

1. Those that are composed of one or more pure tones, such as a note from the piccolo.

2. Those that contain many very closed spaced tones, such as noise of a waterfall or of a jet aircraft engine.

3. combination of the first two, such as whistle in a busy factory.

Effects of noise in man:

1. It may annoy him or it can disturb his sleep.

2. It can interfere with his ability to converse with someone else.

3. It can damage his hearing.

In approaching a problem of noise, consider the following:

A. The source

       1. Can a quieter machine or operation be substituted?

       2. Can noise intensity be reduced?

       3. Can a useful change be made in how the noise is directed?

       4. Are resilient pads beneath the noisy device of any use?

       5. Can a muffler be used?

B. The path from the source to listener

       1. Can the source or the listener readily be moved, so that the two are farther apart, to reduce the sound level?

       2. Should a barrier be erected between the source and the listener?

       3. Will the addition of an absorbing acoustical material result in significant noise reduction?

       4. Is a total enclosure for the source required?

C. The listener

       1. Can he be induced to wear ear plugs or noise-reducing cushions or helmets?

       2. Can he be enclosed in a booth or other quite space?

Sound Terms – Intensity and frequency determines the loudness of a sound. Loudness on the other hand varies with different individuals and often between two ears of the same individual.

(a)   Sone – measure of loudness level expressed on a linear scale. 1sone=40db of a 1 kHz tone.

(b)   Phon – means of evaluating the relative quality of sounds at a different frequencies. Sound pressure levels expressed in db are related to equivalent sounds at 2 kHz.

Hearing Loss – Years of exposure to noise result to hearing loss of varying degree at various frequencies of perceptible sound.

Women exhibit less increase in hearing loss than men.

Management must be informed of the problems that workers have in the working areas.

Heartbeat – 10db

Whisper – 25db

Typewriter clacks – 40db

Average conversation – 65db

Noise of the city street – 95db

Airplane Engine - 120 db (which is trillion times louder than heartbeat).

Any noise louder than 130db would be painful to listen to. To lessen the noise problems, the sound absorbing materials should be available in the working areas or in the place where the noise is untolerable. Rubber, cork, or felt pads should be used

-      Magcalas, Rommel and Bacarizas, Francis