Ventilation
Definition
Ventilation is the process by which ‘clean air’ (normally outdoor air) is intentionally provided to a space and heat & stale air is removed. This may be accomplished by either natural or mechanical means.
Purpose of Ventilation:
- To maintain the right exchange of gases in the body.
- To provide thermal comfort by maintaining adequate heat balance of the body.
- It improves the quality of workplace.
- Ventilation becomes necessary where people/human consumes oxygen and releases carbon dioxide.
- In the factory persons working together cause Air Pollution (lack of oxygen) apart from human body which releases CO2.
- Ventilation provides comfort to the workman and hence efficiency of workman improves.
Control Measures for Ventilation:
- Legal Measures: According to Factory Act 1948, 78, 87 in Chapter III Health Provision Sec 13 deals with “Ventilation and Temperature” in the work area.
- Improving Measures: Adequate ventilation by circulation of fresh air and temperature should be kept below 400C by using temperature ventilation like Fan, A/C.
- Safety Measures: Maximum temperature of the workplace should be around 300C to 800C and minimum 160C. Fresh air should be supplied by artificial ventilation 6 times the cubic capacity of the workplace.
Types of Ventilation
- Natural General Ventilation.
- Mechanical Ventilation.
- Dilution Ventilation.
- Local Exhaust Ventilation.
1. Natural General Ventilation: It can be affected by wind action. It can be achieved by providing enough openings at convenient location. So that natural wind can pass through the span automatically replaced by contaminated / polluted air. This is a cheap and effective method.
2. Mechanical Ventilation: It can be provided in two ways.
a) Blowing: Air from outside into the room resulting in the light positive pressure in the room. Constant flow of air from outside to inside is blowing (fresh air supply).
3. Dilution Ventilation: Dilution ventilation supplies and exhausts large amounts of air to and from an area or building so that the worker can safely expose for 8 hours per day.
It usually involves large exhaust fans placed in the wall or roof of a building. Dilution ventilation controls pollutants generate at a worksite by ventilating the entire workplace.
Advantages:
a) Simplicity
b) Installation cost is less.
4. Local Exhaust Ventilation: The engineering control system is used to capture and reduce contaminates (dust, heat, mist, fume, vapor or gas) released at the sources before it spreads into the workplace.
Example: Diluting & local exhaust,
Silencer to the vehicle,
Filter & absorbers.
Control of Heat Exposure: Man must keep the temperature of his vital organs within narrow limits. If he is to survive exposure to intemperate environment. As heat impinges upon man, his first response in a sensation of discomfort, job in efficiency and soon. Heat reduction methods is as follows:
- Control at source:
The hot process equipment such as furnaces, oven at is segregated or isolated from the main work area. The building housing such as hot equipment should be built with high roof with exhaust chimney arrangement for removal of hot air over the furnaces, oven, etc. - Insulation:
To control the radiation heat from the furnaces, oven, etc. methods like insulation, water cooling or shielding of radiation etc. are adopted. A shield of a sheet of material having properties of high reflection and is placed in between the hot furnaces and the working surroundings. Aluminum sheet has good heat reflection properties. - Personal protection: The work men are to be provided with protective clothing and protective shield or controlling exposure to heat. Aprons, jackets, leggings, helmets, etc. made to standard specifications to withstand the hot atmosphere are to be provided to the workmen.