MICRODYN CAPILLARY MODULES | USER MANUAL
MANN+HUMMEL Water & Fluid Solutions | REVISION DATE: 09/09/2021
9
5
Operation
5.1
GENERAL SYSTEM SET-UP
In cross-flow filtration, a liquid is pumped through the modules. A typical arrangement is shown in Figure 4 below. The favorable
flow velocity for MICRODYN modules ranges between 1-2 m/s (3.3-6.6 ft/s).
5.2
PRESSURE DROP AND TRANSMEMBRANE PRESSURE
For filtration to occur, the inlet, or feed pressure (P
1
), must be greater than the outlet pressure (P
2
) and filtrate pressure (P
F
), as
shown in Figure 5. This difference in pressure, also called pressure drop, is the loss of pressure from the feed end to the
concentrate end of a module and occurs due to the resistance of flow.
To achieve stable filtration, begin operation at a low feed pressure and gradually increase the feed pressure until optimal filtration
performance is achieved. The driving force for filtration is the transmembrane pressure, which is defined by the difference of the
pressure on the filtrate side and the averaged pressure on the feed/concentrate side (see also below equations). The allowable
operating pressure is listed on the respective product data sheet.
Pr
es
sur
e
Module Length
Pressure Drop in
the Module
Effective Operating
Pressure
P
1
P
2
P
F
Concentrate
Permeate
PI
PI
TI
PT
Back Pulse
Tank
FT
Feed
Figure 4
. Simplified flow diagram using MICRODYN modules.
Figure 5
. The pressure drop along the length of the module.
