![]() To achieve controllability for small and/or airtight rooms, mere use of a standard damper in a return duct to control the room pressure is insufficient. This can be formulated as:įigure 5: Controllability is related to the degree of leakage and the volume of a room This is based on the simple correlation that airflow over a ‘resistance’ will generate a pressure drop Dp (Pa). The first solution requires tremendous volumes of air, so the second solution is a more useful approach. In this case the pressure can be increased by two means: 1) by increasing the volume entering the room (and leaking away) or 2) by leakage reduction. Large volumes of air will be able to flow in and out without any significant resistance. This room will have the same pressure as the surrounding environment as the construction is usually far from airtight. To understand the principles governing room pressurisation, consider first a room being within the envelope of a general building. intended to keep specific contaminants in, are not in the scope of this article. Cleanrooms designed for ‘containment’, i.e. Understanding the mechanisms that will create a room pressure, as well as those factors that challenge it, is essential for success. These dampers have to be designed to modulate within a certain airflow range and with a specific accuracy and speed of reaction. Most commonly this is achieved using pressure controlled actuated dampers in the return ducting. To achieve this the HVAC needs to be designed to control the room pressure by some means. Specifying room overpressure in cleanroom design is a common contamination control concept. A broader view based on designed airflow rather than mere room pressure has many benefits, argues Frans Saurwalt of Kropman Contamination Control. Careful design of a facility can make use of air flow to create a protective effect where no physical barrier is presentĬontrolling room pressure is only one aspect of cleanroom facility design when creating segregated zones of different class. ![]() ![]() Differential pressurisation is frequently used as the mechanism to create segregated zones within a controlled environment, but maintaining accurate pressurisation in the face of leakage is a complex task.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |