Open membrane chamber
Internal supports were removed to create a fully open membrane chamber.
Configuration overview
O–CMF–50mL–34deg
Orthogonal centrifugal membrane filter cartridge for fixed-angle centrifuge rotors designed around standard high-speed 50 mL round-bottom polycarbonate tubes.
Centrifugal pressure model. The transmembrane pressure generated at rotor angular velocity ω is
Δp = ½ ρ ω² ( rm² − rs² )
where the radial positions of the membrane (rm) and of the liquid free surface (rs) are referred to the rotor outer radius rmax via two cartridge-geometry constants and the fill volume V:
rm = rmax − δm rs = rmax − ( δs* + αV )
| Nominal feed volume | 13.0 mL |
| Operating fill range | 11–13 mL |
| Membrane chamber volume | 4.6 mL |
| Membrane coupon diameter | 20 mm |
| Effective membrane area | 1.45 cm² |
| Membrane offset, δm (distance rmax − rm) | 0.0318 m |
| Free-surface intercept, δs* (distance rmax − rs at V = 0) | 0.0367 m |
| Free-surface slope, α (rate at which rs moves toward the axis as V increases) | 0.00160 m mL−1 |
Cross-section
Cartridge geometry
Cross-sectional reference showing the radial coordinates used in the centrifugal pressure model.
Design features
Improved capacity
The revised cartridge increases membrane chamber volume to 4.6 mL.
Improved membrane area
The effective membrane area is increased to 1.45 cm², with sealing provided by a compressed elastomeric O-ring.
Operating conditions per rotor
Applying the centrifugal pressure model (see Configuration overview above) at nominal fill volume (13 mL of water at 20 °C), the rotor speed required to reach each target transmembrane pressure is given below. Dashes indicate conditions exceeding the rotor speed limit.
| Δp (bar) | Beckman JA-20 8×50 mL · 34° · 20 000 rpm |
Thermo Sorvall SS-34 8×50 mL · 34° · 20 500 rpm |
Thermo Fiberlite F21-8×50y 8×50 mL · 34° · 20 000 rpm |
Heraeus HFA 15.50 8×50 mL · 34° · 23 300 rpm |
|---|---|---|---|---|
| 2 | 3 347 | 3 373 | 3 373 | 4 301 |
| 5 | 5 293 | 5 335 | 5 335 | 6 801 |
| 10 | 7 485 | 7 544 | 7 544 | 9 619 |
| 15 | 9 167 | 9 239 | 9 239 | 11 781 |
| 20 | 10 587 | 10 668 | 10 668 | 13 600 |
| 30 | 12 965 | 13 067 | 13 067 | 16 658 |
| 40 | 14 971 | 15 087 | 15 087 | 19 234 |
| 50 | 16 740 | 16 870 | 16 870 | 21 506 |
| 60 | 18 333 | 18 478 | 18 478 | — |
| Max Δp | 71.4 bar | 73.8 bar | 70.3 bar | 58.7 bar |
Compact JA-20 free-surface correlation (SI units, with rs in metres and V in millilitres): rs(V) = 0.0713 − 0.00160·V, valid for V ∈ [11, 13] mL.
Research use statement: CentrivaLab products are intended for research and process development use only and are not intended for clinical or diagnostic use.