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Methods of chlorinization. Types of chlorine. Lighting . Ventilation and heating or the microclimate in workplaces
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Methods of chlorinization
Chlorination helps in killing pathogenic bacteria, as salmonella and shigella, but has no effect on spores, virus, and helmenthic ova.
a) Normal chlorinization 1-5 mg/1
b) Hyperchlorinazation: the high dosage is used in:
• unknown source of water
in epidemic situation.
b) Dechlorination: when the residual chlorine may be more than 0, 6 mg/1 which is not allowed for domestic use this is accomplished by use of sulfur dioxide and sodium thiosulphate, or activated carbon filters.
Side effects of high doses of chlorine
• dysfunction of intestinal tract
• change of taste and odour of water
• irritation of the mucus membrane
Types of chlorine
1. Plain chlorine (under pressure gas)
2. Chloramine: ammonia may be added to react with chlorine, forming a new oxidizing agent named chloramine, it is more effective in controlling taste and odour, more effective in control of organic matter, more stable during long periods of time.
3. Bleaching powder: 25% or 36% of active chlorine (it is loose and unstable compound).
Factors on which the efficiency of disinfecting power of chlorine demand depend on:
1)pH of water
2) Time of contact
3) Temperature of water (time of reaction in summег 30 min, in winter 60 min)
4) Level of turbidity
Exercise
1. Write your conclusion about the quality of water, and select the methods of purification's of underground water. Color-none \ Transparency - 20 cm. Hardness - 6, 4 mg/1 Nitrate- 16, 3 mg/1 Chloride- 12, 5 mg/1 Coli-index – 20, Fluoride - 1 mg/1, ammonia - 0, 3 mg/1, number of bacteria – 100mg/l
2. Find out the amount of 25% bleaching powsler уоu need for chlorination 10001 of water (from river
LIGHTING
Good natural and artificial fighting is important in buildings, and it is essential for efficient vision. The light effect the biological and physical activity of the body.
Public health reasons for adequate lighting had been stated to be protection against eye strain and prevention of accidents.
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The unit of measuring amount of light (Lux)
The gauge (Luxometer)
Sourse of light:
1) Natural light (Sun):
Infrared – 2000 – 760 nm, visible light - 760-400nm. UV-rays - 400-200nm
2) Artificial light (Lamps - incandescent and fluorescent daylight lamps). Artificial direct lighting should not fall into the eyes. It must give a general illumination of the whole room.
The fluorescent lamps are better than the incandescent lamps, because the colour of their light approximate to the day light colour. The fluorescent lamps do not give a shadows but give a general illumination of the area.
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Side effect of the fluorescent lamps: Noise and alter the rotary movement.
Recommended Lighting regulations include the following:
1) The total glass area (sk) of the windows in each room should be not less than 20% of the floor area
2) The reflecting power of ceilings and walls is not less than 60%
3) Consideration should be given to the direction in which windows faces so as to give a good conditions of lighting (sun light) southeast.
Good natural and artificial lighting is important in all houses and workplaces wherever possible, full use should be made in sunlight.
The requirement for good artificial light includes: a - Sufficiency of light, b-Absence of glare, с - Absence of intense shadows, d - Should be far as possible approximate to the day light colour.
Biological effect of light
Light includes effect on biological rhythms of body, physical activity and adrenocortical secretion and effect the vision.
The amount of natural day light in rooms depend on manyfactors:
a) Geographical situation
b) The distance between the buildings not less than 30m
c) Trees and greens around the building
d) Brightness of the sky, and the clouds
e) The climate
Internal factors:
a) Colour of the walls and reflecting power
b) (C. L) SK (the ratio between the area of the widows and the area of the room
c) (A. C) KZ (the ratio between the height topmost of the window and the distance between the window and the opposite wall.
d) KEO (the ratio of natural daylight outside of the room and the room light on the workplace).
Exercises
1. Find out the number of fluorescent (80 wt) (daylight) lamps for classroom. Area - 40 m, height - 3m (use especial tables).
2. Find out the level of: LC, DC ( SK, KZ) in classroom two windows (area 8 m2) the topmost height of the window above the floor 3 m, of the classroom 4x5 m, and write your conclusion.
VENTILATION AND HEATING OR THE MICROCLIMATE IN WORKPLACES
A careful balance must be maintained between heat gained and lost from the human body and this, depends on four factors:
1) Air temperature
2) Air velocity.
3) Humidity in the air,
4) Atmosphere pressure
A cold wall will absorb heat and lower the temperature, while radiation of heat from warm walls help to maintain the temperature.
The greater the movement of air, the greater the cooling power as evaporation is increased.
Drier the air the more water vapor it can absorb. If the humidity in the air is high, there is a corresponding reduction in cooling power. Heat can be lost from the body in three ways:
1) Evaporation
2) Convention
3) Radiation.
If air temperature is between 24-37°, heal fess, by radiation and convection falls but evaporation loss increases
Microclimate: these are external physical factors which influence on rae thennoregulation of the body and its condition. The factors are:
1. Air temperature 18-20°
2. Air velocity 03-0, 5 m/c
3. Humidity in the air 40-60%
4. The atmospheric pressure about ±752
5. Level of oxygen 20%
6. Level of C02 0, 1%
Types of ventilation
A - Natural ventilation. В - Artificial ventilation (mechanical).
Relative humidity: the relation between the (absolute) humidity and the humidity of the rooms at the time of analysis.
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The instrument: Psychrometer Assmana
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r. Ax 100
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R. h =
R. h - Relative humidity, a. h- Absolute humidity S. p - Saturation point
Picture 2.
Relative humidity: Percentage of water vapour in the atmosphere relative to that present when the air is saturated at the same temperature.
The movement of the air in the rooms measuring by katather mometer (it is a large bulb spirit graduated thermometer).
Atmospheric pressure causes:
Mountain sickness: because of lower atmospheric pressure and low % of oxygen tension, at 4000-6000 m above from the sea level.
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