Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

The correct answer is 20.

In operating theatres, it is essential to maintain a sterile environment to prevent infection. To achieve this, the air supplied to the operating theatre is typically a mixture of recirculated air and outside air. The percentage of outside air is usually around 20% to:

1. Remove stale air and odours
2. Introduce fresh air with a higher oxygen content
3. Help control humidity and temperature

Using 20% outside air also helps to:
1. Reduce the risk of airborne infections.
2. Maintain a stable air pressure inside the operating theatre.
3. Meet the standards for operating theatre ventilation set by organizations such as the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).

The other options are not accurate:

- Zero: Using no outside air would lead to a buildup of stale air and odours.
- 50: Using too much outside air could compromise the sterile environment and increase the risk of airborne infections.
- 100: Using only outside air would make it difficult to control temperature, humidity, and air pressure, and could compromise the sterile environment.

Here the exact percentage of outside air may vary depending on specific hospital policies and local regulations.

May be the patient requires fresh air to breathe or in other words the contamination present in operation theater because of humans has to be replaced by 100% outside air for ventilation purpose.

Yes, you are right @Kedar.

Please explain it.