Turning On The Vaporizer - VisualSonics VEVO Operator's Manual

Chapter 4: Operating the Vaporizer: Turning on the vaporizer
Vaporizer valve assembly
Turning on the
vaporizer
18 VisualSonics Vevo Compact Anesthesia System Operator Manual
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In the 'Off' position, there is a direct link between the 'inlet' and 'outlet'
within the vaporizer. When the dial is turned 'On' the carrier gas is split
into two streams: bypass and vaporizing chamber flow.
Carrier gas entering the vaporizing chamber flows through agent
saturated wicks. As the carrier gas passes through the wick, it becomes
saturated with vapor.
The amount of agent picked up in the vaporizing stream will vary due
either to variation in room temperature or to the cooling which takes
place when the agent is vaporized. Each causes changes in the effective
vapor pressures of the anesthetic agents.
Unless some form of compensating device was used, the output of the
vaporizer for a given flow and dial setting would change with
temperature.
This principle is one of many reasons explaining why it is recklessly
dangerous to use a jar and wick style vaporizer with extremely volatile
anesthetic agents such as Halothane and Isoflurane.
This vaporizer has a temperature-compensating device (thermostat) to
control the proportion of carrier gas entering the vaporizing chamber.
If the temperature of the vaporizer falls, the thermostat closes and more
carrier gas is allowed into the vaporizing chamber. If the temperature of
the vaporizer increases, the thermostat opens and less carrier gas is
allowed into the vaporizing chamber. In this way the output of the
vaporizer remains constant under conditions of changing temperature
within the clinical ranges of the vaporizer.
To turn the vaporizer On, press the control dial release button, and
simultaneously turn the control dial counter-clockwise to the desired
concentration value.
To prevent the inadvertent delivery of small concentrations, the control
dial should be turned 'Off' when the vaporizer is not in use.
Control dial
release button
Vaporizer in
'Off' position
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