PPandPES

Depth and Membrane Filtration—Information

Basic filtration info.

PES cartridges are often called "membrane" or "absolute" filters. They have very high efficiencies--over 99.98%.
PP are depth filters. Plate-and-frame is also depth filter. Lenticular is identical to plate-and-frame except easier and cleaner to setup, but at a much higher cost.
PES are never the first filtration. They always follow PP. Plate-and-frame or lenticular is often used before PP.
Clogging of a filter quickly, after a small volume, simply means a coarser filtration is required. (or perhaps more effective fining or other clarification in the tank).
If a filter clogs, it is working correctly. If a filter does not clog, then it may not be working correctly. Or you can move to a finer filtration.
Increasing pressure is a clear indicator that a filter is becoming clogged.
30 psi is typically the maximum pressure for filtration of wine/beer/spirits. Many cartridges can withstand higher pressures, but the efficiency of the filters diminish at these higher pressures.
You can backwash PP cartridges. However, backwashing PES presents great risk that the "membrane" becomes separated from the support---thus destroying the filter. This is not a risk with PP.
The human eye can see 40 micron and larger particles. Thus the eye is a very poor instrument for ascertaining what filtration is required and how effective filtration is. Yeast are ~5 micron for example.
The difference between 'clear' and 'brilliant' is the amount of light scatter from small particles. It can be very difficult for the eye to see light scatter through 4" (the diameter of a wine bottle). As a point of reference, smog scatters light. But smog can rarely be detected by the eye thru even 100', but quite easy to see off in the distance.
Sheet filters (plate-and-frame) and PP cartridge do much the same. The greatest difference is simply the volume. Sheet can handle larger volumes. However, PP cartridges have efficiencies of ~90% while sheets are only about ~65% efficient. This is the primary reason why plate-and-frame filtration is nearly always followed by PP if the final filtration is PES.

Cartridge Filters

Specifications of PES and PP cartridge filters

Clean room for manufacturing PES and PP cartridge filters.

Absolute vs High Efficiency vs Nominal
In practical terms, Absolute means all particulates below a specified size are removed.
In quantitative terms, most mfgs employ the standard of >99.98% efficiency.

PES cartridges exceed this 99.98% standard.

High Efficiency is typically reserved for filters of >90% efficiency. Our PP filters exceed this 90% standard.

Nominal filters are typically 60-70% efficient. Filter sheets and lenticular filters are nominal filters. Also, spun polypropylene as you see at hardware stores are nominal filters.
We do not sell nominal filters except our ACF carbon filter is also a nominal 5 micron filter.

What is BETA? Beta is simply another means of expressing efficiency. A filter of 99% efficiency allows 1 particulate out of 100 to pass. The Beta = 100. A filter of 99.98% efficiency lets 2 in 10,000 pass ( or 1 in 5000). Beta = 5000. So Absolute filters have Beta > 5000.

["Absolute" PP filters?? Some manufacturers refer to high-efficiency PP cartridges as "absolute" or perhaps "semi-absolute". This is misleading because they are not "absolute" at the labeled porosity. For example, our 0.22 micron PP cartridge is 95% efficient (not absolute) for 0.22 micron particles, but 99.98% efficient (which is absolute) for 2.5 micron particles. We reserve the term "absolute" to PES cartridges to avoid confusion, and also to accurately reflect the intended use of the filter--as a final microbial filter.]

PP High Efficiency specs.

Manufactured in Class 100,000 cleanroom.
Support, core, and end caps are PP
NSF certified pleated PP media
Orings silicone
Sealing by Thermal bonding, no adhesives
Filter area, 10" cartridge, 0.6 m²
Maximum Forward differential pressure 60 psid @73°F, 22 psid @ 185°F for water.
Maximum Forward differential pressure 30 psid @73°F for beer, wine, and other products with suspended particles
Maximum Reverse differential pressure 30 psid @140°F with pure water (cleaning)
pH 1-14
Maximum working temperature 140° F
May be hot water sanitized for 30 cycles using purified water at 185° F for 30 minutes.
Bacterial endotoxins <0.25 EU/ml as determined by the LAL test.
Liquid Use : Beer, wine, liquor and other alcoholic drinks. Mineral water and purified water. Security filtration for reverse osmosis.

ACF specs

Same as PP, and
Iodine Adorption Value 900mg/g
Nominal 5 micron filter

PES and PES+PP specs.

Each and ever filter is integrity tested, either bubble point or diffusion test.
Manufactured in Class 100,000 cleanroom.
Support, core, and end caps are PP
Integrity tested
Each filter flushed with pure water
Media of PES. Pleated assymetric and hydrophilic PES
Media of PES+PP. A layer of polypropylene depth filter combined with a layer of modified polyethersulfone hydrophilic membrane in a pleated configuration.
Orings silicone
Sealing by Thermal bonding, no adhesives
Filter area, 10" cartridge, 0.63 m²
Maximum Forward differential pressure 60 psid @73°F, 15 psid @ 185°F for water.
Maximum Forward differential pressure 30 psid @73°F for beer, wine, and other products with suspended particles
Flow rate and pressure drop per 10" cartridge, >6.6 GPM at 3 psi
Do not reverse flow
PES Bubble point ≥24 psi, water 25° C. Flush for 15 minutes at 45 L/min for 30" cartridge (15 L/min for 10") with pure water to remove air.
PES+PP Bubble point is the same. However, it is very difficult to properly wet with water because PP layer is hydrophobic. It can be done easily with 95% ethanol, but we do not recommend this due to fire hazard.
pH 1-13
Maximum working temperature of PES is 140°F
Maximum working temperature of PES+PP is 176° F (PES+PP has extra stainless steel layer)
May be hot water sanitized for 30 cycles using purified water at 185° F for 30 minutes.
Filter cartridge integrity was maintained after continuous 20 steam-in-place cycles of 30 minutes at 127°C or 30 autoclave cycles of 30 minutes at 123°C.
Bacterial endotoxins <0.25 EU/ml as determined by the LAL test.
Liquid Use : Beer, wine, liquor and other alcoholic drinks. Mineral water and purified water. Security filtration for reverse osmosis

Cleaning PES cartridges

General Sterilization/Sanitation Methods

Chemical: Peracetic acid, chlorinated alkaline products, bleach, sulfur dioxide, and hydrogen peroxide at typical sanitation concentrations and temperatures.
Hot Water: 185°F at 5 psi
Autoclave: 250°F for 30 minutes at 2 psi up to 30 cycles
In-Line Steam: 250°F for 30 minutes at 2 psi up to 30 cycles

Do NOT backwash (reverse flow) PES filters

Specific Procedures

Procedure 1. This procedure does not involve caustic or acid.
a)Forward flow with cold water for 5 minutes to remove product.
b)Forward flow with hot water (175° F) for 5 minutes.
c)Now recirculate with hot water for 15-30 minutes. Leave hot water in unit overnight.
d)Rinse with hot water for 2 minutest the next morning.
f) Air-dry cartridge and store in open to avoid mold growth. You can store the cartridge in the filter housing, but be sure to open the valves so air can penetrate.
Cleaning solutions should be filtered. Flow rate ~ 4 GPM per 10" cartridge.

If Procedure 1 is not effective, this procedure may be used.

Caustic is dangerous. Wear rubber gloves, boots, safety glasses and apron.

Procedure 2. Hot cautic cleaning
a)Forward flow with cold water for 10 minutes to remove product
b)Forward flow with hot caustic solution (140°-150° F) for 30 minutes. (1% NaOH). This is recirculation but discard the first gallon or so.
c)Forward flow (recirculate) with acid solution for 5 minutes. Any weak acid is suitable including vinegar.
d)Forward flow with cold water for 30 minutes. Do not recirculate in this step. You must be certain that all caustic and acid is removed.
f) Air-dry cartridge and store in open to avoid mold growth. You can store the cartridge in the filter housing, but be sure to open the valves so air can penetrate.

Cleaning solutions should be filtered.
Flow rate should be 4 GPM/10" cartridge for hot caustic. 4-10 GPM/10" cartridge for cold water and acid solution.

Procedure 3. Alternative cleaning procedure using cold caustic:

a)Forward flow with cold water for 10 minutes to remove product
b)Soak overnight--up to 12 hours-- in caustic solution (1% NaOH)
c)Soak in acid solution for one hour (any weak acid including vinegar)
d)Forward flow with cold water for 30 minutes. Do not recirculate. You must be certain to remove all caustic and acid.
f) Air-dry cartridge and store in open to avoid mold growth. You can store the cartridge in the filter housing, but be sure to open the valves so air can penetrate.

Cleaning solutions should be filtered.
Flow rates should be 4-10 GPM/10" cartridge.

Cleaning PP cartridges

The cleaning procedure for PP cartridges is the same except you can reverse flow through PP cartridges. Be careful not to exceed the maximum pressure for reverse flow.

Inserting Filter Cartridges
Lubricate the orings before inserting into housing. Food grade silicone spray or even water will work well.

Cartridge Filters vs Filter Sheets Depth vs Membrane Filtration (Volume Filters vs Surface Filters) Generally, depth filtration (sheet filter for example) is used to remove the vast majority of particulates. ABSOLUTE PES membrane cartridges are used just before bottling to ensure yeast (but not bacteria) removal. PP pleated cartridge filters are used ahead of PES to protect them from being overloaded. Also, PP cartridges are used in place of sheet filters for smaller volumes.
Depth Filtration involves trapping particulates within the volume of the filter material. Filters sheets are essentially a maze of paper fibers. Particulates penetrate the entire volume of the paper until they reach a dead end and are trapped. Filter Sheets are Volume (Depth) Filters High Dirt Loading Capacity Cannot be cleaned and reused. Made of paper (cellulose) so, once wet, they physically collapse in a relatively short time. (Filter sheets have a small amount of Polypropylene plastic strands to make them more sturdy). Generally broad filtration spectrum. Relativley inexpensive	Absolute PES Cartridge Filters are Membrane Filters. Membrane filters are used as a last step to ensure microbial stability. PES 0.45 micron will remove all yeast but not bacteria for wine and beer. Membrane Filters are Surface Filters. In the simplest form, they are a thin layer of material (PES) with well defined and uniform hole sizes. Particulates smaller than the hole size pass through, anything larger than the hole size gets stopped on the surface of the membrane. >99.999% Efficiency (Absolute) Large Surface Area Sharp filtration spectrum (because hole size can be very well defined) Low Dirt Loading Capacity (a 10" PES membrane cartridge has about 1/5 the dirt holding capacity of a single 40x40 sheet) Can be cleaned and reused. High Efficiency PP Pleated Cartridge Filters have both depth and membrane filtration features. >95% Efficiency Large Surface Area Low Dirt Holding Capacity compared to filter sheets, but much larger than PES membrane cartridges Made of polymers and are quite durable so they have relatively long life. Relatively inexpensive compared to PES cartridges Can be cleaned and reused. Sharp Filtration Spectrum and high efficiency. See Zeta Potential discussion below.
Dirt Holding Capacity is the important characteristic of Sheet Filters. Surface Area is the important characteristic of Membrane (PES) and High Efficiency PP cartridges.
Dirt Holding Capacity (DHC) defines the volume (or weight) of particulates a filter medium can hold. The Dirt Holding Capacity of a Depth Filter is essentially the volume of the filter. For a 40x40 Filter Sheet, the Dirt Holding Capacity is ~0.5 liters. (40cm x 40 cm x 3.4 mm).	Dirt Holding Capacity of a cartridge filter. PES membrane filters have very low DHC. DHC of High efficiency PP cartridges are still relatively low compared to sheet filters, although greater than PES cartridges. It depends on the micron rating, but generally it takes at least one 10" PP cartridge to replace a single 40x40 sheet for bulk filtration.
Filter Sheets and PP cartridges filter by two other mechanisms. Although the amount of particulates trapped by these mechanisms may not be large, it is important to understand them because they present limitations. A filter sheet is also a surface filter. See the Porosity discussion below Electrostatic filtration -- Zeta Potential	Surface Area of 10" Cartridge filter is typically 0.6 m². (for comparison, this is equal to the surface area of ~5 40x40 sheets).
What is Zeta Potential? Zeta Potential is the basis of another mechanism of filtration that is particularly important in depth filters (sheets for example). This mechanism of filtration is not size dependent—rather due to electrostatic forces. For example, negatively charged particulates (most particulates in wine or beer are negatively charged) stick to a positively charged surface layer on the filter medium. It is most important to understand that this mechanism only exists when the solution is flowing and it takes a moment to establish the mechanism when flow begins. When you stop the flow on a plate and frame filter, the particles held by the zeta potential are released. When you begin again, some will pass through the filter. This is why it is recommended to recycle the first bit of wine or beer.	Zeta Potential and High Efficiency PP cartridges. High Efficiency PP cartridges have features of both membrane and depth filters. As such, electrostatic filtering (i.e. Zeta) is an important mechanism for PP cartridges. For the same reasons discussed at left, if you stop and then restart filtering, some particulates held trapped by the electrostatic force will pass through.