 |
 |
 |
 |
>>>>>I was told earlier by someone at BD that the inside dimensions of
>>>>> the FACScan flow cell are 180 x 430 micrometers.
These are indeed the correct dimensions. (The viewing orifice is a rectangle
nominally 177.8 X 431.8 microns) For other interested readers, short axis is
front-to-back, long axis is along the laser beam. However, the max (useful)
size is really determined by the sample injection tube, which has a smaller ID
(nominally 177.8 with tolerances from 152.4 to 203.2) The material used to date
has been from one mill run and was under the nominal (actually about 165).
To get back to the original question, the max size for a biological sample
should be around 70 micron to reduce the potential for doublets and aggregates
blocking the inlet tube.
>>>>>I've measured sheath consumption at 14 ml/min,
I think the value should be more like 18 mL/min.
>>>>> which translates to sheath velocity of 3 m/s using the above numbers,
>>>>> and core stream diameters of 26 or 10 ("hi", "lo") micrometers, which
>>>>> seems too large. Your dimesions would give a velocity around 16 m/s
>>>>> and core stream diameters about 12 and 5 microns. Which is correct?
Neither is exactly correct. Your calculation assumes "plug" flow through the
cell. There is, in fact, a velocity gradient which peaks at the core and gives
the hydrodynamic focusing of the sample. The core velocity is 6 m/s. The core
shape is about 30 X 10 microns in HI (per Bob Hoffman) and should be an ellipse
with the same dimensions but 5X less area for LO. (We'll let you calculate that,
our trigonometry is a little slow today)
Tom_Frey@bdis.com
Tony_Ward@bdis.com
|
|
|
|