A. Air Conditioning. В. Gas Supply. С. Ventilation

I. Gas supply has come to be very widely used. 2. In industrial buildings three types of ventilation are in use so as to control dangerous gases and dusts. 3. In buildings such as homes, the leakage of air through cracks in doors and windows is usually sufficient. 4. As for the purpose air-conditioning system may be described as winter, summer and all-year. 5. The main utilization of natural gas is as a clean, convenient, economical source of heat. 6. Natural gas supply is used also as a heat source in com­mercial establishments. 7. Certain industrial process requirements and hu­man comfort are the two major factors to be considered when designing air-conditioning system. 8. Air conditioning is meant for the control of temperature, humidity, purity and motion of the air in an enclosure. 9. The main purpose of ventilation is to carry away excess heat and odours.

THEME 7.

CENTRAL AIR-CONDITIONING SYSTEMS.

1. Answer the questions:

• What are the ways of air-conditioning the buildings?

• What equipment for air-conditioning the building is known?

2. Read the text and give the headline:

The constant volume terminal system is widely used because of its engineering simplicity and excellent temperature and humidity control ca­pabilities. One distinct disadvantage is that it has the highest energy cost because all circulated air must be cooled to a predetermined constant tem­perature to meet the design load of any space served by the system and reheat is required at all partial load conditions. This system does not have diversity and thus requires the highest installed refrigeration and fan ca­pacities.

WORDS TO BE STUDIED AND MEMORIZED:

1.constant volume, variable temperature system

2.variable volume, constant temperature system

3.to supply a constant amount of conditioned-air at proper temperature

4.to supply a varying amount of constant temperature conditioned - air

5.supply air temperature

6.a cooled air stream

7.a heated or bypass air stream

8.space temperature control

9.to optimize system efficiency