Pellicon
®
3 Cassettes Installation and User Guide
11
5. Slowly raise the air pressure to the
recommended test value and wait
5 minutes to purge residual water
in the permeate line. Permeate line
must be completey emptied before
measuring air flow. Do not exceed
the recommended air pressure
as this may displace water from
the membrane pores and result in
excessively high air flow (a false
failure). Rewet the membrane if this
occurs.
6. After the diffusion air flow pressure
stabilizes, measure and record the
air pressure, temperature and the
air flow rate exiting the permeate
line. The air flow rate may be
measured with an air flow meter or
by measuring the air displaced into a
submerged and inverted volumetric
cylinder as shown in the figure above.
7. Compare the measured air flow
rate to the specified flow value on
the Certificate of Quality included
with the cassette. If the measured
flow rate exceeds the specified flow
value, refer to the Troubleshooting
section of this guide.
Measurement of
Normalized Water
Permeability
The normalized water permeability (NWP)
for Pellicon
®
3 Cassettes should be
established prior to the first product contact
of each filter. New membranes should be
cleaned, flushed and integrity tested before
measuring NWP. The NWP measured at
this point is used as a benchmark against
subsequent NWP measurements to
determine cleaning efficacy.
1. Close the tank drain valve.
2. Fill the tank with filtered, deionized
water, water for injection, or
reverse osmosis permeate. The
flush water must be extremely pure
to avoid fouling the membranes
or introducing other contaminants
into the system. The NWP may
be measured with solutions other
than water (i.e. storage solution
or buffer) as long as the same
conditions and solution are used for
each measurement.
3. Fully open the retentate (and
permeate valve if present) and
direct both the retentate and
permeate lines back to the tank.
4. Open the tank drain valve
5. Turn on the feed pump and pump
water into the feed port of the
Pellicon
®
holder. The recommended
feed flow rate for Pellicon
®
A or C
screens is 4 to 6 L/min/m². (The
same conditions MUST be used each
time NWP is measured in order to
ensure accuracy.)
6. Recirculate the water for 10 minutes.
Ensure that the pressure and the
temperature conditions are stable.
7. Record the feed and permeate flow
rate, feed, retentate, and permeate
pressures, and the temperature of
the water.
8. At the end of the recirculation, fully
open the retentate and filtrate lines,
turn off the feed pump, and drain
the retentate and filtrate piping.
9. Calculate the NWP:
NWP=
R•F/[A(P
in
+ P
out
/2)-P
p
]
These units yield
LMH/bar [liters/m
2
•hours•bar]
Calculate:
R = Permeate Flow Rate in L/hour
P in = Feed Pressure in bar
P out = Retentate Pressure in bar
T = Water Temperatures in °C
Pp = Permeate Pressure (if non-
zero) in bar
A = Total Filter area in m
2
F = Temperature correction factor
from table below.
The acceptance criterion for cleaning
efficacy as measured by NWP is
membrane and application specific,
and may vary between plants. Key
