Controlled environments act as secluded clean spaces for performing select applications in a manner that protects the internal samples or materials and/or the workers involved. Air pressure is a key component of a cleanroom. The internal pressure and, by design, the differential pressure, are closely regulated and maintained. Basic chemistry tells us that high pressure air has greater mass than low pressure air, and given the opportunity, will flow into the less dense environment.
Ascending or descending pressure differentials are part of the foundation of most controlled environments. Maintaining a specific differential between adjacent areas reduces the inflow of airborne particulates and/or prevents hazardous materials from escaping. The type of application dictates whether a positive or negative pressure space is required. So, how do these two pressure types differ?