How to Store Lenticular Modules Between Uses


Recommendations

Some of the things we love about Seitz Supradisc™ II lenticular filters are that they are backflushable, hot water sanitizable and storable. This means you can use them over and over again without the media warping until they are full of solids or when a regeneration procedure doesn’t bring the differential pressure back down.

In this excerpt, we will discuss the best solutions for storing your modules correctly between uses to ensure longer use and higher throughput. They are always stored in a liquid solution and shouldn’t be allowed to dry out between uses.

You can either store your modules inside the housing - Pall recommends steaming or hot water sanitizing them after a regeneration and then placing the emptied housing under at least 1 bar (14.5 psi) of pressure with a food grade gas like nitrogen. If the pressure stays above this threshold, the media can be stored like this for many weeks. This only works if your seals are sound so that pressure cannot escape overnight. Keep in mind that many housings are not pressure rated for gas pressure, only liquid pressure, so for safety purposes, don’t pressurize a housing without that certification in hand.

The most common storage method is to store the modules in the housing or in a suitable container with a lid where they can be weighed down to keep them fully submerged in the storage solution. For storage in a solution for longer than two days, we recommend removing the silicone gaskets or O-rings on the modules, otherwise, they will become brittle and break up into little pieces. A brew fermentation bucket that is not tapered is suitable for the 12” modules, whereas food grade plastic trash cans or Rubbermaid totes with lids are suitable for the 16” modules.

HERE ARE A FEW SOLUTIONS TO STORE YOUR MODULES IN

1. Inexpensive Ethanol (vodka) for 12” Modules

If you choose to store your modules in vodka or your own produced spirits, make sure that it is at least 40 degrees proof, but that it does not exceed 135 degrees proof. When choosing this method, be aware that your module should be purged with gas before storage to ensure that little to no dilution of the alcohol takes place. Remember to bring the backpressure up to 5 psi when purging to force the gas into all the pores to get the most of the liquid out.

If the alcohol % of the vodka is under 20%, you will likely see spoilage organisms start to grow inside the module. Therefore, we only recommend this method for 12” modules. 16” modules have a lot of internal surface area and require a whole lot more alcohol. We also see a poor distribution of the alcohol within the depth of a 16” module which inevitably leads to spoilage.


2. Citric Acid with SO2

When choosing this method, it’s a good idea to run this pickle through the modules before removing them into their respective storage containers to make sure you have even distribution. We recommend that the pH of the solution is pH 2.0 or lower and that you always maintain at least 50ppm SO2 and up to 200 ppm SO2 concentration. You may need to add more SO2 periodically. We suggest dropping in an effervescent Inodose SO2 tablet every now and then to make sure the SO2 level stays high enough, otherwise lactic acid bacteria will strike quickly. You don’t need a lot of citric acid to drop the pH to 2.0 since water generally has a very low buffer capacity. Generally, a 2% solution by weight is enough citric acid to drop the pH to the right level.


3. Other Acids

The manufacturers of cellulose filter media advise against long-term contact with phosphoric acid, nitric acid and sanitizers like Star San and peracetic acid. These acids tend to break down the resin that keeps the cellulose media together and that can lead to a pulpy mess over time, which in turn can lead to the filter media landing up in your filtered product. Running these chemicals through the media just before filtration is acceptable, but longer contact time is detrimental to the media. Some of them can also break down over time and cause off-flavors in the media at which point bacteria can easily start to grow again.

Whatever storage solution you choose, make sure that you regularly inspect the solution to make sure that your modules are properly submerged, that the gaskets have been removed, and that your solution is still sanitary.





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