Mindray BC-3600: WBC counts fail after the first measurement
What happened
In this case the analyzer ran its first measurement normally, then reported a WBC clog on every subsequent count. Repeated flushes and aperture burns did not clear it, and an air bubble was seen in the volumetric tube, breaking the liquid column.
What was checked
- Repeated flushes and aperture burns were done to rule out a real blockage at the WBC aperture.
- The count time between the first and second optocoupler triggers was checked — reported in the case as up to about 18 seconds — and the fluid column was not reaching the second sensor within that window.
- The filter behind the air supply valve was inspected for dirt.
- The valve, together with its adjacent tube, was moved to another position to see whether the fault migrated; the valve was also tested on its own.
Cause
The probable cause in this case: crumbling adhesive at the tee of the volumetric tube let air be drawn in, so the liquid column did not reach the second optocoupler in the allowed time and the instrument logged a clog. A dirty filter behind the air valve or a leaking valve could give the same picture.
The cause is probable and was not fully confirmed.
What was done
The engineers recommended sealing the suspect tee joint (thick grease was suggested as a quick test), replacing or repositioning the valve, and checking or replacing the filter behind the air valve. The outcome was reported as probable, so confirm the leak is gone by watching a full count cycle with no bubble in the tube before closing the job.
Safety
Hematology fluidics hold potentially infectious samples: wear gloves and eye protection when opening the counting path, decontaminate any spilled fluid, and run a leak/background check before returning the analyzer to use.
Lesson: When a clog error survives flushes and burns and an air bubble breaks the fluid column, look for an air leak in the counting path — joints, valves, filter — before blaming the aperture.
Covered in the course: Lab Analyser Service — Level 2: Fault-Finding →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.