Blease Datum L Series, User Manual

Page: 48 / 52

Datum 'L' Vaporizer
User Manual
48
7.9.2 Effect of IPPV on Output
The greatest effects of IPPV (Intermittent Positive Pressure
Ventilation) are at low concentration settings and low flow rates.
The Datum
®
has been designed to comply with the conditions
specified in BS4272:Part 3:1989.
7.10 Gas Composition
The Blease Datum
®
vaporizer is calibrated using air at 5 l/min.
Therefore the concentration control is at its most accurate when air
is used. The output may vary when the gas composition is changed
due to differences in density and viscosity affecting the bypass
splitting ratio. Air was chosen as the calibration gas because the
concentration delivered is then in the middle of the range available
for anaesthesia.
WARNING: This device must not be used with anything other
than Dry Medical Gases.
7.10.1 Oxygen
The use of oxygen will produce a slight rise in output which is
unlikely to exceed 15 % of the set value or 0.3 volume percentage.
The effect is greater at high flows, with a smaller change occurring
at lower flows.
7.10.2 Nitrous Oxide
The use of nitrous oxide will produce a slight fall in output, which is
unlikely to exceed 15% in normal conditions.
7.10.3 Carbon Dioxide
At or below the maximum normal concentration of 5% the effect is
negligible.
7.10.4 Helium
Helium-enriched mixtures are likely to reduce the output
concentration of the vaporizer, so it is recommended that an
analyser be used if accurate concentrations of anaesthetic agent
are required.