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9. If the anaesthetic machine on which the vaporizer is fitted is left for a period of time with no gases
flowing, sensitive analysers 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 OFF. This is a normal
machine characteristic caused by residual vapour left in the machine from previous use.
10. When the vaporizer is turned from OFF to 0% or above after a period out of use, an increased
concentration may occur which rapidly stabilises to the set concentration within approximately
10 seconds at 5 litres/minute flow.
11. At the 0 % setting it is not abnormal for small steady concentrations to be observable on sensitive
analysers.
9.0
Analytical Techniques
For field checking of the state of calibration, many techniques and analysers are available. Datex-
Ohmeda would not recommend any one technique or analyser in preference to another, but the
calibration and reliability of analysers 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 analysers 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
for at least three hours.
2. With the vaporizer securely mounted, drain the vaporizer as detailed in Section 4.6 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 OFF and then carefully and quickly pour a measured 50
millilitres of agent into the vaporizer without spilling.
4.
Leave the vaporizer at a nominal temperature of 21
temperature has stabilised.
5. Set the flowrate to 5 litres/minute oxygen.
6.
Turn the control dial to 2%, note the time and check that the flowrate is still 5 litres/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 OFF and turn the oxygen OFF.
8. Drain the vaporizer as detailed previously in Instruction 2 and measure the amount of liquid
drained off. The amount of liquid consumed should be as follows:
Fluotec
Enfluratec
Isotec
Sevotec
Appropriate action must be taken to handle the exhaust gases and spillage.
It must be appreciated that the preceding method is designed to be a quick and easy check of vaporizer
operation and that the method is somewhat imprecise. Nevertheless, it would be unusual for the
measured liquid consumption to vary by more than 25% of the preceding values.
Tec 5 Vaporizer
O & M Manual Part No. 1105-0100-000
13.5 millilitres
15.5 millilitres
15.5 millilitres
16.6 millilitres
± 2° C for one hour to help to ensure that the
± 2° C
Page 29
August 1999
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