Datex-Ohmeda Aestiva 7900 SmartVent, Service Manual

Page: 69 / 181

4/Tests and Troubleshooting
1503-0151-000 5/26/0 4-23
Verify Flow
The software allows the user to set the flow from 0 (closed) to 120 LPM. The user
can then verify that the flow output of the ventilator is correct and/or that the flow
sensors read the correct output.
Remarks
Note : Gas exiting through the bleed resistor must be accounted for or occluded
when measuring flow valve output.
This service tool can be used for directly controlling the output of the flow valve.
Gas from the 7900 flow valve exits from three separate areas; the two drive
hoses and the bleed resistor. Independent measurements of flow valve output
must capture all gas from these ports or provide for their occlusion. Be sure to
remove all occlusion devices prior to returning the system to service.
This tool can provide flow for a check of the flow sensor’s span, but only in an
approximate sense. Variations between the flow sensor output and the flow
valve setting can vary by as much as 25%. Use the Flow Sensor Operational
Test as a more accurate measurement of flow sensor competency at lower
flows.