In case of any airflow issues you should always check the following:
All the tubes inside the instrument are connected.
E.g. the tubes leading to the preconditioning unit at the top are often forgotten to be attached after maintenance.
The Venturi tubes are in the right direction.
The Venturi tubes are connected to the right pressure sensor.
The Venturi pressure connection tubes are not switched.
If you have a flowmeter available (like TSI 4000 series): Check that the flowrates match to those shown by the measurement program. Note that these are volumetric flowrates, not translated to STP conditions.
Sample flowrate should be measured from the exhaust.
Sheath flowrates should be measured by disconnecting the tubes going up into the preconditioning unit and measuring from the side of the blowers.
If using Ashcroft pressure sensors: Check that the electric wiring of the pressure sensors is intact.
Description The standard deviation of a flow sensor signal is abnormally high.
Solution In addition to the standard airflow checks, please see that strong wind is not blowing directly into the inlet.
Description The blower control signal is at maximum, however according to the flow sensors the flow speed remains below the target value. The system can not increase the blower speed any further.
Solution In addition to the standard airflow checks, check that there are no obstructions. Pay attention that all tubes and electric connections to the blowers are intact.
Description The blower control signal is at minimum, however according to the flow sensors the flow speed remains above the target value.
Solution In addition to the standard airflow checks, pay attention that all tubes and electric connections to the blowers are intact.
