Bronkhorst CORI-FILL - Manual (Page 23)

9.17.075
Bronkhorst Cori-Tech BV
23
9 Very small batch dosing
Challenge:
Dosing a very small batch (60 mg) in a short period (1 sec.)
Flow needed:
0.060 g * 3600 sec = 216 g/h (M13 using a shut-off valve)
Please keep in mind that the opening + closing will be around 0.5 seconds.
Total dosing time will be 1 + 0.5 = 1.5 sec.
Points of attention:
Use a small dosing needle.
To calibrate, handle weighing scale with care; dose under fluid level to avoid drops at the needle. Weighing scale should have
right resolution and should be mounted horizontally on spirit level.
Monitor density and temperature to detect gas bubbles in the fluid. Make sure there are no gas bubbles in the fluid. They will
cause deviations in batches. Best is to use pressurized vessels without direct contact of the gas to the liquid to avoid dissolution
of gas in the liquid. E.g. vessel with diaphragm.
Make sure pressure to vessel is very constant. Behavior of pressure controller can be seen in batch results. Better is to
pressurize the vessel and close the gas inlet valve to stabilize the pressure in the valve (this can only be done using low flow
rates).
Make sure to have short line between valve and dosing spot (needle) as on the pictures.
Make sure FlowDDE and FlowPlot polling/sampling time is fast enough. This is 100 msec. for standard. For this kind of fast
dosing tests, times should be set down to approx. 20..25 msec.