Figure 9-19 Simplified schematic of Datex-Ohmeda Aladin Cassette Vaporizer. The arrows represent flow from the flow meters, and the open circles represent anesthetic vapor. The heart of the vaporizer is the electronically controlled flow control valve located in the outlet of the vaporizing chamber. CPU, central processing unit, F_BC , flow-measurement unit that measures flow through the bypass chamber, F_VC , flow-measurement unit that measures flow through the vaporizing chamber, P, pressure sensor, T, temperature sensor. (Modified from Andrews, JJ: Operating Principles of the Datex-Ohmeda Aladin Cassette Vaporizer: A Collection of Color Illustrations. Washington, DC, Library of Congress, 2000.)