Clean Rooms HVAC Design

Clean Rooms HVAC Design and how to control the pressure, temperature, and humidity:

Definition: 

A clean room is a controlled environment used in manufacturing or scientific research that has low levels of environmental pollutants such as dust, airborne microbes, aerosol particles, and chemical vapors. The HVAC system design for clean rooms must be carefully planned to maintain a specific level of cleanliness.

Major Equipment Used: 

Major equipment used in clean room HVAC design includes: a) Air handling units (AHUs) - AHUs are responsible for creating and maintaining the required levels of temperature, humidity, and air cleanliness. b) Filters - Filters are used to remove particles and contaminants from the incoming air. c) Dampers - Dampers are used to control the flow of air into and out of the clean room. d) Heating, ventilation, and air conditioning (HVAC) controls - HVAC controls are used to monitor and adjust the temperature, humidity, and pressure within the clean room.

Clean Room HVAC Design: 

Clean Room HVAC design involves several key factors including: a) Airflow direction - The airflow should always flow from a cleaner area to a less clean area to prevent contamination. b) Positive/negative pressure - The clean room must have either positive or negative pressure depending on the application. Positive pressure is used to keep contaminants out of the room, while negative pressure is used to prevent contaminants from escaping into adjacent areas. c) Temperature and humidity control - The temperature and humidity must be closely controlled to ensure product quality and safety.

Controlling Pressure, Temperature, and Humidity: 

To maintain the desired levels of pressure, temperature, and humidity within the clean room, the following components may be used: 

​a) Pressure sensors - Pressure sensors are used to monitor the pressure within the room and ensure it remains within the desired range. 

​b) Airflow sensors - Airflow sensors are used to monitor the velocity and direction of air flow within the room. 

​c) Temperature sensors - Temperature sensors are used to monitor the temperature within the room and ensure it remains within the desired range. 

​d) Humidity sensors - Humidity sensors are used to monitor the relative humidity within the room and ensure it remains within the desired range. 

​e) HVAC controls - HVAC controls are used to adjust the temperature, humidity, and pressure within the clean room as needed. These controls may include dampers, fans, heaters, and cooling coils.

To maintain positive pressure within the clean room, the supply air must be greater than the return air. This is achieved by using a higher number of supply air changes per hour compared to return air changes per hour. For negative pressure, the opposite is true.

To control temperature and humidity, the HVAC system must be designed to provide sufficient heating, cooling, and dehumidification capacity. The correct equipment sizing and selection must be determined based on the required level of cleanliness and the specific requirements of the application.

Other Factors to Consider: 

​a) Filters - Filters are an essential component of clean room HVAC design, as they remove particles and contaminants from the incoming air. They must be properly sized and maintained to ensure optimal performance. 

​b) Airlocks - Airlocks are used to prevent the entry of contaminants from outside sources into the clean room. 

​c) Flooring - The flooring in a clean room must be designed to minimize the buildup of particles and contaminants. It should also be easy to clean and maintain. 

​d) Lighting - The lighting in a clean room must be carefully selected to minimize the production of particles and reduce the amount of heat generated.

Summary

In summary, Clean Room HVAC design must be carefully planned and executed to maintain a precise level of cleanliness. This involves controlling factors such as airflow direction, positive or negative pressure, temperature, and humidity while ensuring the proper selection and maintenance of equipment such as filters, dampers, and HVAC controls.