The Variable Bypass Vaporizer
The Sevoflurane Vaporizer is an example if a variable bypss vaporizer that delivers vaporized anesthetic gas into an anesthesia machine for inhalation during surgery. Fresh gas flow enters the vaporizer and becomes saturated with anesthetic gas, then exits the other end. A concentration dial at the top allows the user to adjust the output concentration as desired. A bimetallic strip leans to one side as temperature changes occur, automatically adjusting to ensure concentration output is as dialed.
The Desflurane vaporizer is modified from the traditional bypass vaporizer. It has two parallel circuits, each with a resister. In the first circuit fresh gas flows and is regulated by a resister. In the second circuit desflurane is heated in a sump. As the pressure rises a shut off valve opens and allows desflurane to exit through a resister.