DATREND Systems venTest, Руководство по эксплуатации

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venTest OPERATORS MANUAL
Measurements with default values after power on:
Default values for trigger conditions have been chosen to minimize effects caused by switching
values.
The default values may not be valid in all cases because some parts of the flow are not measured
or the trigger may fail. It is recommended to use the graphical display to evaluate the quality of
triggering and adjust the thresholds and delays depending on application.
Incorrect triggering may not be immediately obvious in a volume measurement whereas time
measurements (TI, TE, I/E and Frequency) may lead to significant deviations. The basic default
settings are a good starting point from which the optimum settings can be determined.
In general, once a setting has been defined for an application (test setup, ventilator, modes) it will
normally be used in the future.
Using the display set function, these optimum settings can be stored.
Optimization of trigger conditions:
It is not easy to define general rules for trigger conditions due to the wide variety of possibilities.
• In a closed loop system (circle system) it may be useful to switch from flow to pressure
triggering
• In open loop systems only flow triggering is possible, because there is no pressure to be
detected.
• Unexpected peak values of flow caused by switching values should be suppressed by
selecting a trigger delay instead of a higher flow trigger value.
• Similar effects from exhaust values can be suppressed by an end trigger delay.
• Set the trigger levels no higher than necessary, so as much flow as possible can be
detected for the volume calculation.
Over time, optimum trigger conditions for the different measuring tasks emerge.
High Frequency Ventilators:
When in High Frequency mode, the trigger levels are preset for optimal detection, and are not
user adjustable.
Operation/Chapter 4
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