Siemens 547-323B RCM FM BAC +/-.25"WC(62.5PA).25%FSSiemens 547 323B RCM FM BAC + . 25"wc(62. 5Pa). 25%FSDescriptionIn a hospital, laboratory, or animal research facility, the integrity of the ventilation control system is at the heart of a contaminant free environment. Whether a room is to be maintained at a negative pressure to prevent contaminants from escaping into adjacent areas or positive pressure to protect patients with compromised immune systems, the proper pressurization of the room is