It is known to control and monitor the pressurization of a room and/or laboratory to ensure occupant health and safety, as well as to protect sensitive manufactured products. Healthcare facilities and research laboratories may utilize complex pressurization schemes in order to protect patients, personnel and researchers from hazardous viruses, pathogens, or other toxins. For example, a healthcare or research facility may seal and partially depressurize (generate a negative static pressure) a room or laboratory that contains a hazardous material. Thus, if a breach or accident occurs, air would flow towards the hazardous material, thereby containing and/or minimizing the potential spread or contamination.
Biological laboratories are often maintained at a negative static pressure specifically to prevent airflow out of the laboratory room. These laboratory rooms are constructed and classified as biosafety level 1, 2, 3 and 4 based on, for example, the nature and danger associated with the work and materials housed within the laboratory. Biosafety Level 4 (BSL-4) is the highest safety level classification indicating the greatest risk to individuals within a laboratory itself, the facility in which the laboratory is housed, and the surrounding areas. BSL-4 rated laboratories are constructed to be virtually leakproof, e.g., they are sealed so tightly that virtually no unintended air transfer or release occurs, thus minimizing the chance of contaminants escaping the laboratory. Alternatively, a BSL-4 rated laboratory could be a sealed room or enclosure into which another sealed, air tight container is placed. Regardless, in an effort to control or prevent the spread of a hazardous contaminants, BSL-4 rated laboratories are typically geographically isolated and operated at a high negative static pressure, e.g., 0.1 to 0.5 inches w.c. or 25 to 125 Pa.
In order to ensure and control the airflow and ventilation within a BSL-4 rated laboratory, the mechanical ventilation system(s) supplying the laboratory will typically be designed and controlled to deliver desired airflow rates and maintain selected pressure relationships between the laboratory and adjacent spaces. Certain pressure relationships must be maintained or controlled during transient conditions such as, for example, changes in pressure caused by the opening of a door or entrance. Known laboratory pressurization schemes such as, for example, differential flow control or airflow tracking are inapplicable in leakproof and/or sealed environments such as a BSL-4 rated laboratory where the relative supply and exhaust airflows are constant and may not be independently adjusted to establish a pressure differential. Similarly, direct pressure control and cascade pressure are unsuitable for tightly sealed environments where the transient conditions can severely and rapidly impact the desired pressure relationship.
There exists a need for a pressurization scheme or strategy that may be utilized in a tightly sealed environment such as, for example, a BSL-4 rated laboratory, to achieve and maintain a specific pressure relationship.