A Perspective on Filter Cartridge Issues

Transcription

1 A Perspective on Filter Cartridge Issues Michigan Grape and Wine Conference February 24 th 26th

2 HOW LONG WILL MY FILTERS LAST? UNCERTAIN

3 Prefiltration Life Factors General rule of thumb: Prefiltration rating = 4 5 X final filter Better efficiencies and lower ratings = shorter throughput Undersized Recommended Flow per TIE: Membrane: < 3 GPM Pleated Media: < 5 GPM Depth Media: < 5 GPM One Size Does not fit all Optimization based on varietal type

4 Life Factors Effectiveness of Cleaning Process Progressive decay of cycle life may indicate low cleaning effectiveness. Longer Time Different Cleaner Excessive Plugging The higher the degree of plugging (high pressure drop, lower flow), the more difficult it is to clean the filter. Ideal to limit plugging to 50% 60% = 2 3 X initial pressure drop; ½ - ⅓ initial flow.

5 DON T ALL 0.45 MICRON FILTERS RETAIN MICROBES? YES, MAYBE, NO.

6 Microbial Retention How is retention achieved? Membranes are used to retain bacteria and yeast. Not all membranes are rated to retain microbes Depth type filters generally have no microbial retention claims.

7 Microbial Retention ASTM Standard Test Method for Determining Bacterial Retention Of Membrane Filters Utilized For Liquid Filtration. The standard test for determining ability of a membrane to retain microorganisms. Challenge level is 10 7 /cm 2 which equates to about total in a typical membrane filter of approximately 7 ft 2. Values often reported as LRV Log Reduction Value For example, if there were 1000 (10 3 ) in the effluent, you would get an LRV of 8 ( = 10 8 ). Membrane performance validated by Integrity Test

8 DO I HAVE TO INTEGRITY TEST MY MEMBRANE FILTERS? HIGHLY RECOMMENDED

9 Integrity Testing Why Integrity test? Manufacturers Characterize Membrane Filter Performance Quality Control of Manufacturing Process Develop and Validate Marketing Claims End User Verify Filter Integrity Improve Process Effectiveness/Consistency

10 Integrity Testing Theory Typical 0.2 µm membrane cartridge (per 10 ) has 6.5 x µm 2 of surface area (7 square feet). Area of a single 0.2 µm pore = µm 2 # of pores/cartridge can be calculated by: (6.5 x µm 2 ) x 0.65 (% porosity of membrane) (0.031 µm 2 ) 1.36 x pores (trillion) The goal of integrity testing is to confirm that none of these pores exceeds the specification.

11 Integrity Testing What are the different integrity tests? Bubble Point Minimum Critical Bubble Point Bulk Flow Bubble Point Diffusive Flow Pressure Hold

12 What is Bubble Point? Integrity Testing Bubble Point With a completely wetted membrane, it is the pressure at which the liquid in the pores is displaced. Basic Procedure Pre-wet membrane Apply pressure to upstream side to 80% of bubble point Increase at 1 psi increments until bubbles appear Upstream Pressure

13 What is diffusive flow? Integrity Testing Diffusive Flow The volume of gas which permeates a completely wetted membrane at a given pressure. FACT: Wetted membranes are impermeable to bulk flow of gas. Test typically run at 80% of the bubble point pressure. Also called forward flow, diffusional flow.

14 Integrity Testing Diffusive Flow Basic Procedure Pre-wet membrane Apply pressure to upstream side to 80% of bubble point Measure volume of gas collected on downstream side Upstream Pressure

15 Integrity Testing Manual Bubble Point / Diffusional Flow Test Stand Air Source Regulator Pressure Gauge Test Housing Graduated Cylinder w/ water Inverted Burette Drain

16 What is Pressure Hold? Integrity Testing Pressure Hold Allows for an evaluation of an entire assembly including multi-rounds. Necessary in multiround vessels Pressure is applied to a sealed vessel on the upstream side. The maximum amount of pressure loss that is permitted. Pressure loss in an integral system is due only to diffusion through the membrane. Must be calculated for each system based upon total volume.

17 Basic Procedure Integrity Testing Pressure Hold Pre-wet the filter elements Apply pressure to upstream side - (typically psi) Allow system to equilibrate (5-10 minutes) Monitor pressure loss over time (5-10 minutes.) Upstream Pressure Diffusion

18 Integrity Testing Automated What is an Automated Integrity Tester? In line system capable of determining most integrity test values. Upstream measurements avoids downstream contamination Significantly reduces operator error

19 Integrity Testing Least Common Cause of Integrity Failure Non integral filter Common Causes of Integrity Failure Insufficient wetting O-Ring failure: improper installation Wrong wetting fluid: values differ by fluid Wrong pressure/filter Operator error

20 HOW CAN FILTERS BE CLEANED AND STORED? A NUMBER OF METHODS ARE ACCEPTABLE.

21 Cleaning and Sanitizing Filters Cleaning, sanitizing and sterilizing filters is a common practice in order to achieve process economics. Most filters are not manufactured to be backwashed, but with care, it is possible in combination with cleaning processes. Cautions Check chemical compatibility of ALL components Increased temperature can may increase the aggressive nature of a cleaning/sanitizing agent Temperature decreases the maximum differential pressure of a cartridge due to softening of the polypropylene components.

22 Cleaning and Sanitizing Filters Cleaning Use the following cleaning agents for cleaning filter cartridges. Immerse with cartridge open end up and soak in a container that has the prescribed concentration of the agent for at least 30 minutes. Triton X-100: Add 15 drops of Triton X to one gallon (3.79 liters) of warm water and then mix well. Triton X is made by Roche Diagnostics. LiquiNox/Alconox: Follow instructions provided by manufacturer on product packaging. Minnclean TF: Add 30 grams of Minnclean to one gallon (3.79 liters) of warm water and mix well. Acid: Immerse the cartridges in 1% solution of citric, acetic, nitric, phosphoric or hydrochloric acid. Caustic: Rinse cartridges or soak overnight in 0.5-5% NaOH solution. Hot caustic at 122 F (50 C) is even more effective.

23 Cleaning and Sanitizing Filters Sanitizing Use the following sanitizing agents to properly sanitize cartridges prior to use in critical applications. Immerse with cartridge open end up and soak in the prescribed concentration of the agent for minutes.. Sodium Hypochlorite (Bleach): 5-10 ppm solution in lukewarm water. 70% Ethanol: Immerse the cartridges (Buna N O-Rings not compatible). 10% Hydrogen Peroxide: Immerse the cartridges in 10% H2O2. Quaternary Ammonium quats : Add 2 oz. (59 ml) of Ammonium to one gallon (3.79 liters) of water (200 ppm). Acid: Immerse the cartridges in 1% solution of citric, acetic, nitric, phosphoric or hydrochloric acid. Peracetic Acid: Immerse cartridges in ppm solution. Caustic: Rinse cartridges or soak overnight in 0.5-5% NaOH solution. Hot caustic at 122 F (50 C) is even more effective.

24 Sterilizing Cleaning and Sanitizing Filters Heat is an effective method to sanitize and/or sterilize a filter. Careful monitoring of the differential pressure must be done to assure structural integrity of the filter. Pressure maximum can be reduce to as low as 3 5 PSID. Hot Water: Raise clean water temperature to 185 F (85 C) and immerse the cartridges with open end up for 30 minutes. For inline hot water flow, do not exceed 3 psid (.21 bar) pressure drop across the cartridge. Steam: Raise the steam temperature to 250 F (121 C) and expose the cartridge to steam for 30 minutes. For inline hot steam, do not exceed more than 5.0 psid (.34 bar) pressure drop across the cartridge.

25 Thank you Any sufficiently advanced technology is indistinguishable from magic Arthur C. Clarke