Filter Knowledge

The In-line Steam Sterilization Specifications of Sterile Grade Filter Cartridge

The bacterial removal terminal filters need to be in-line steam steriled for the safety production in pharmaceutical industries, because of their different high polymer materials construction, the steam sterilization have to followed such procedures as below strictly, or the filters would be damaged easily.

In-line Steam Sterilization Procedures:

1).Fully close the outlet valve, slightly open the inlet valve to adjust the steam pressure at 0.1-0.13 Mbar.

2).Slightly open the outlet valve and close that valve when steam begins to discharge, holding 30min at pressure 0.1MPa.(Note: Do not fully open the outlet valve, or the mass steam would damage the filter by high temperature)

3). When sterilization line is complete, immediately introduce clear air or N2 into the system, keep the pressure at 0.02 Mpa above the steam pressure.

4). Holding until the temperature is below 100℃, increase the air pressure to cool the filter cartridge.

5). If the filter cartridge is too wet to be flowed through by steam easily , we need to evaporate the water in the filter first at low steam pressure, then increase to the requested pressure for sterilization when the steam release from the outlet valve.


Important Notes:

a)Strictly control the steam pressure, keep it at 0.13Mpa when sterilization.

b)Steam used for sterilization should be free from condensation, which would flow through the membrane and damage it by high temperature.

c)Adequate means for condensate drainage should be employed to ensure steam is free from condensate in sterilization.

d)Cooling the filter system is the key step, an ideal way is to close the valves and maintain the pressure to cool naturally, or according to the above step 3. High pressure air and cold water are neither allowed to damage the filter cartridge by out of shape.

e)In sterilization, slowly adjust the outlet valve to control the differential pressure below 0.12Mpa.

f)The integrity test is necessary to assure the filter is undamaged after steam sterilization.

Integrity Test

The filters should be confirmed structural integrity before and after use, three methods: bubble point test, diffusion test and water invasion test can be employed according to the GMP. The wetting liquids are standard reagents(water, alcohol, etc) or process liquid.

1.Principle: The integrity test value is detected by statistical method, according to the differences of surface tension or other physical parameters of the different fluids.

2.Detected filter types: Membrane filters(micron<1 um), Bacterial removal membrane filters, Virus removal membrane filters, Hydrophobic air filters

3.Test items: bubble point, diffusion, pressure holding or water invasion test;

4.Connection method

Cartridge filter test:

Cartridge filter test

Plate filter test:

Plate filter test

5.Integrity testing procedures
a. Wet the filter cartridge or membrane with the appropriate fluid
b. Connect the integrity tester with air source and power source, then link with the filter housing.
c.Start the integrity tester, input test procedure and data;
d. Install the wetted filter cartridge or membrane in the housing, auto detect and decide the results.

6. Notes of Integrity Tester

1).Working condition:
a. Power:100-240 V, 50/60Hz, 1.6A;
b. Air source requirements: clear, room temperature, dry, oil free compressed air or N2,
c. Air pressure: <7000mbar, normally 6000mbar;
d.Operating temperature: 5-40℃;
e.Relative humidity: 20~80%

a. Move carefully;
b.Stable the power voltage;
c. Ensure the quality of air and pressure stability;
d. Keep the instrument clean;
e. Avoid the liquid into the internal instrument;
f. Calibrate the pressure sensor periodically, Consult the instrument supplier;
g. When not use for a long time, place the filter integrity tester in boxes, and store in a dry place.

How To Choose The Filter Correctly?


Main    Features


Mixed    Cellulose


  1. ①high porosity,    good retention capacity,
  2. ②Not resist to    organic solvent, strong acid & alkaline liquor
  3. ③Highly cost    effective
  4. ①Bacterials or particles removal in small batch or    laboratory
  5. ②The determination of    E.coli in water
  6. ③2 um and 5 um membrane    could be applied for fuel filtration


Natural    hydrophilicity, resist to alkaline liquor and organic solvent, especially    Ketone, Ester, Ether
  1. ①particles or bacterials removal
  2. ②photoresist filtration    in electronic industry
  3. ③kinds of solvent and pharmaceuticals    filtration


Good hydrophilicity,    high protein adsorption, not resist to keton, strong acid and alkalines
  1. ①Bacterial culture and biochemical    analysis in medical research and diagnosis,
  2. ②DNA, RNA hybridization    experiments and verification
  3. ③liquid scintillation    detection, radioactive tracer preparative.
  4. ④Electrophoresis, trace    element analysis, etc.

Cellulose    acetate

Good hydrophilicity,    low protein adsorption, not resist to keton, strong acid and alkalines
  1. ①Suit for Low molecular    alcohols, grease solution filtration
  2. ②Special components    measurement

Glass    microfiber

High    flow rate and temperature resistance, good adsorption to colloid, oil and    particles.
  1. ①air pollution    monitoring
  2. ②Biological large moleculars    filtration
  3. ③prefiltration


acid and alkali    resistant, wear and impact resistant, evenly distributed micropore. Widely applied in the    injection, oral liquids, wine, beverage, water, air filtration, etc


High throughput, low    protein adsorption, good chemical compatibility and thermostability, high    mechanical strength,soluble in polar solvents(Chloroform, Acetone,etc)
  1. ①Pharmaceuticals: LVP,    SVP, Serum,etc terminal filtration
  2. ②Food: Beverage, wines,    etc terminal filtration
  3. ③Ultrapure water    terminal filtration

Polyvinylidene    Fluoride

  1. ①Hydrophobic membrane
  2. ②Good stability
  3. ③Thin, high flow rate
  4. ④Wide chemical compatibility
  5. ⑤High temperature    resistance(-40-260℃)
  6. ⑥Turn to hydrophilic membrane    by alcohol treatment
  7. ①Remove particles to improve the grade of alcohol, acid,    alkane, aromatics and halogenated hydrocarbon solvents,etc
  8. ②Air sterile filtration in fermentation
  9. ③Nonspecific protein    separation and purification
  10. ④The concentration of    the aqueous solution, chemical separation and recycling


Resist to strong    alkaline, acid and high temperature(-40-260℃), have hydrophobic membrane and hydrophilic membrane
  1. ①Hydrophilic:    Clarification of strong acids and alkali, Special chemical reagents filtration
  2. ②Hydrophobic: air/gas    sterile filtration
How Long Is The Service Life Of Filter Cartridge?

Below is the time to exchange the filter cartridge, whichever occurs first.

1).The filter cartridge fail to the integrity test.
2).The differential pressure have been above 2 bar.
3).The flow rate couldn’t meet the production request.
4).The validated servicing life have been reached.

Preservation Method Of Filter Cartridge

The filter cartridge should be well packaged before use(sterile grade filter cartridge need to be vacuum packaged), then store in a cool, clean, dry place, avoid the sunshine, rain, or heat source;

The filter cartridge needs to be flushed and sterile after use, then dip in fresh 5% NaCl solution for short storage or been dried for long storage.

The Dry Method Of Filter Cartridge

Completely dry the filter cartridge in electric drying oven at 55℃~60 for 24h or longer time, until the filter cartridge quality change less than 1% in 1 h.

Chemical Compatibility Table

Chemical Name

Nylon PES PP PTEE PVDF Silicone Viton EPDM


Pentanol R R R R R NR R R
  Benzyl Alcohol R R R R R LR R R
  Butanol R R R R R NR   NR
  Ethyl Alcohol R R R R R R LR R
  Isopropanol R R R R R R NR R
  Methyl Alcohol R R R R R R -- R
  Diethyl ether R R LR R R LR NR NR


Isopropyl ethers --- --- R R R NR NR NR
  Dioxane   --- R R R NR NR  
  Tetrahydrofuran R NR LR LR LR NR NR R

Aromatic Hydrocarbon

  Methylbenzene NR LR NR LR LR NR R NR


Ethylidene Glycol R R R R R R R R
  Glycerin R R R R R R R R
  Propylene Glycol   NR R R R R R R


Tetrachloromethane LR LR LR LR LR NR R NR
  Trichloromethane LR NR LR LR LR NR R NR
  Ethylene dichloride LR NR LR LR LR NR LR LR
  Dichloromethane LR NR LR LR LR NR LR NR
  Perchloroethylene --- LR LR LR LR NR R NR
  Trichloro ethylene LR LR LR NR NR NR R NR


Acetic acid NR   R R R LR NR LR
  Hydrochloric acid (strong) NR LR R R R NR R LR
  Hydrochloric acid (6N) NR -- R R R NR R LR
  Nitrate (strong) NR NR R R R LR LR NR
  Nitrate (6N) NR --- R R R LR R NR
  phosphoric acid(Strong) NR --- R R R NR R NR
  Sulfate (strong) NR NR R R R NR R NR
  Hydrofluoric acid (6N) NR --- NR R R NR -- NR



Amyl Acetate LR --   R R NR NR R
  n-Butyl Acetate LR --- LR R R NR NR R
  Acetic Ether LR LR LR R R   NR R
  Methyl Acetate LR NR   R R -- NR R
  Isopropyl Acetate -- R R R R LR NR R


Ammonium Hydroxide(3N) R R R R R R R R
  Ammonium hydroxide(6N) R R R R R R LR LR
  Potassium Hydroxide(3N) R R R R R LR R R
  Sodium Hydroxide(3N) R R R R R R R R
  Sodium Hydroxide(6N) R R R R R R R LR


Cottonseed Oil R -- --- R R R R LR
  Lubricating Oil R NR R R R R R R
  Peanut Oil R --- R R R R R LR
  Sesame Oil R NR R R R R R R


Acetone R NR R R R NR NR R
  Cyclohexanone --- NR R R R NR NR R
  Methyl Ethyl Ketone LR -- R R R NR NR R
  Methyl Isobutyl Ketone LR NR R R R NR NR LR


Phenylamine LR NR LR LR R NR R R
  Dimethylformamide R NR R R R R NR R
  Formaldehyde 37% R R R R R R NR R
  Formaldehyde 4% R R R R R R R R
  Gasoline R R R R R NR R R
  Hexane -- LR LR LR LR NR R NR
  Kerosene -- R R R R NR R NR
  Phenol R NR   R R NR   NR
  Turpentine -- R LR R R NR R NR
  Water R R R R R R R R
  Acetonitrile LR R LR R R -- NR R
  Molybdenum Sulfate R -- R R R R -- R


10)This chart is intended only as a reference. R=Resistant, LR= Limited Resistance, NR=Not Resistant, --=Not Testing.