Datex-Ohmeda D-Tec Operations Instructions download pdf (Page 29)

Page 24 D-Tec Vaporizer

August 2001 O & M Manual Part No. 1107-0622-000

9.7 Effects Of Output At Varied Altitudes

The D-Tec Vaporizer has been calibrated in % v/v and the calibration is not affected by ambient

pressure changes. The partial pressure of the delivered agent at any selected dial setting varies directly

with the changes in ambient air pressure. The required dial setting may be calculated using the

following formula:

Required Dial Setting = Normal Dial Setting % v/v x

The table below shows the dial setting on a D-Tec Vaporizer at altitudes of 1000 m and 2000 m

respectively above sea level:

Normal Dial Required Dial Setting %

Setting % v/v

At an altitude of At an altitude of

1000 m (3282 feet) 2000 m (6564 feet)

5 5.5 6

10 11 12.5

14 17 18

9.8 Effects Of Ambient Temperature

The performance of the D-Tec Vaporizer is not significantly affected by the temperature variations

within the operating range specified in Section 9.3.

9.9 Effects Of Back Pressure

Fluctuating Back Pressure does not significantly affect the output of the D-Tec.

Steady Back Pressure does not significantly affect the concentration of the agent delivered (v/v), but

does increase partial pressure of the agent. The increase is in the ratio of total back pressure to the

vaporizer calibration pressure of 760 mm Hg.

9.10 Effects Of Carrier Gas Composition

Small output decreases can occur when the carrier gas composition is changed from 100% oxygen.

When either air or nitrous oxide is employed as the carrier gas, the output is lowered compared to the

output when oxygen is the carrier gas. This effect is the greatest (up to 20% of setting) at low flows

when nitrous oxide is employed, but using nitrous oxide reduces the required inspired concentrations

of volatile agent which can, depending upon the proportion, mitigate the decreases in output from the

vaporizer.

760 mm Hg

ambient pressure (mm Hg)

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Datex-Ohmeda D-Tec Operations Instructions Page 29