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Tec 7 Vaporizer
Analytical techniques
5-4
7.
If unexpected results occur, it is also worthwhile checking for sources of error
such as the flowmeter, leaks or absorption by adjacent components.
8.
Full account must be taken of any extraneous effects on the analyzer that may
arise from changes in the carrier gas composition.
9.
If the anesthetic machine on which the vaporizer is fitted is left for a period of
time with no gases flowing, sensitive analyzers may detect small concentrations
of agent for a short time at the machine outlet after the gas flow is turned ON with
the vaporizer turned to
residual vapor left in the machine from previous use.
10. When the vaporizer is turned from
an increased concentration may occur that rapidly stabilizes to the set
concentration within approximately 10 seconds at 5 liters/minute flow.
11. At the 0% setting it is normal for small steady concentrations to be observable on
sensitive analyzers.
For field checking of the state of calibration, many techniques and analyzers are
available. Datex-Ohmeda would not recommend any one technique or analyzer in
preference to another, but the calibration and reliability of analyzers must be
realistically considered and account must be taken of errors of use.
The following method of checking can be used where special equipment is not
available or where a secondary check of analyzers is desired. The characteristics of the
vaporizer are such that, if the vaporizer is satisfactory at one dial setting, it should be
satisfactory at all other graduations.
1.
Ensure that the vaporizer is at least half full and has been at an ambient
temperature of 21 ± 2° C for at least three hours.
2.
With the vaporizer securely mounted, drain the vaporizer as detailed in Section 4
and, after draining, ensure that either the drain plug and the filler cap are both
securely tightened or the port valve is fully closed and the locking clamp is in the
up position, as appropriate.
3.
Check that the control dial is turned to
measured 50 milliliters of agent into the vaporizer without spilling.
4.
Leave the vaporizer at a nominal temperature of 21 ± 2° C for one hour to help to
ensure that the temperature has stabilized.
5.
Set the flowrate to 5 liters/minute oxygen.
6.
Turn the control dial to 2%, note the time and check that the flowrate is still 5
liters/minute. Readjust the flowrate as necessary.
7.
Leave the vaporizer at this setting for 30 minutes. Periodically check and adjust
the flowrate as necessary. Turn the vaporizer to
. This is a normal machine characteristic caused by
to 0% or above after a period out of use,
and then carefully and quickly pour a
and turn the oxygen OFF.
1175-0013-000
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