4
Liqui-Cel
®
Membrane Contactors
Cleaning Guidelines
III. Chemical Compatibility/Sanitization/Detergents
Table 1 shows the maximum recommended exposure times for several chemicals, which can be
used to clean or sanitize a Liqui-Cel
®
Membrane Contactor. To determine the total exposure time
as a function of concentration, divide the value shown in column 2 of Table 1 by the actual
chemical concentration. The resulting value is the total number of hours the contactor can be
exposed to a specific chemical concentration.
Table 1: Sanitizing Guidelines
Column 2
Column 3
Chemical
Concentration-hours at Room
Temperature
Maximum Recommended Chemical
Concentration*
Chlorine pH > 7
24000 ppm-hours
100 ppm
Hydrogen Peroxide
4800 %-hours
10% wt.
Peracetic acid
4800 ppm-hours
100 ppm
* Exposure times were determined when the fiber tensile strength and elongation values just began to decrease.
The test conditions did not exceed these maximum concentrations and testing was completed at 23 °C. Using higher
concentrations is not recommended and at elevated temperatures the expected life is much shorter.
Exposure Time Calculations
(Note that these are very rough calculations and should at best be
considered as estimates.)
Case 1: 2% hydrogen peroxide sanitation every day for 30 minutes.
a) What is the total exposure time for a solution of hydrogen peroxide at 2% concentration at
room temperature?
b) What is the maximum number of 30 minute cycles that the contactor can be subjected to
using this solution at room temperature?
c) Assume the desired number of cycles will be 365 times per year and the contactor will have
a lifetime of 3 years.
d) Should this cleaning chemical protocol be used?
Solution
a) Divide 4800 % - hours by 2%. Total maximum allowed cumulative exposure time is about
2400 hours.
b) Divide 2400 hours by 0.5 hours (30 minutes). Total number of cycles is about 4800.
c) Using 365 cycles per year and an expected lifetime of 3 years, the total number of exposure
cycles is 1095 (365 * 3 years). It would be safe to use this chemical for daily cleaning for 30
minutes per day at 2% concentration at room temperature since 1095 cycles < 4800 cycles.
The total life expectancy of a Liqui-Cel Membrane Contactor is affected by many factors, one
of which is the chemical cleaning cycle. Do not assume the total number of exposure cycles
can be used to predict the estimated lifetime of a contactor. Use this total number of cycles to
judge whether the contactor lifetime will be affected by the cleaning cycle. In the case above,
compare the number of theoretical cleaning cycles (4800 cycles) to the desired number of
cleaning cycles over the expected lifetime of the contactor (1095 cycles). The conclusion in
this example is that cleaning cycles will probably not reduce the 3-year lifetime of the
membrane.
NOTICE
Avoid contacting membrane to surfactants or solvents to prevent membrane wet-out.
Do not expose membrane to oxidizing species such as ozone, chlorine, hydrogen
peroxide, peracetic acid, etc. to prevent membrane oxidation.
Содержание MEMBRANA Liqui-Cel
Страница 1: ...Cleaning Guidelines ...
