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pre bottling filter microns


daveflintstone

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Has anyone experience with comparing pre bottling filter micron sizes?  I mean the difference between 0.2, 0.5, 1.0 micron cartridges on the final spirit.  I'm wondering if going up to 1 micron will result in any particular (ha see what I did there) difference. 

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While I've not bottled spirits myself, I've sold a whole lot of filters. Since there are no takers yet, I'll chime in:

What I hear from customers when they change subtle micron sizes is that there is usually no difference in appearance, but there may be changes to flow rate and filter longevity. It depends on the product, the filter, and how observant or persnickety the user is.

In general, you shouldn't see a difference at submicron levels. Polishing filtration—that is, filtration for appearance—typically happens at > 1µm. Filtration at < 1µm is typically for the reduction of micro organisms. The human eye can't see individual particles smaller than about 70 µm. You can see the effects of a lot of small particles together as haze, which typically means that the product has particles in the 1-5 µm range.

So, you should be able to remove most particulate haze by filtering down to 1 micron. Pretty straightforward…except 1 micron doesn't always mean 1 micron. Depending on the type of filter you're using and the manufacturer, 1 micron may be a "nominal" rating. For example, Brand X may call a filter 1 micron if it removes 90% of particles at 1 micron, whereas Brand Y may call a filter 1 micron only if it removes 99% of particles at 1 micron. So the results you see from filtering at 1µm using Brand X's filters may be different than the results you see using Brand Y's.

Take it all together, and basing filter selection on the experience of other users may not translate to how different filters work for you. I typically advise customers to try a couple of different 10" filters themselves and see if there are any noticeable differences. That's the only way to know for sure.

On the other hand, I've had customers who swear that a 0.65µm absolute final filter gives their product a "Bud Light" brightness that they did not see at, say 1.2µm absolute. Every situation is different…

Anyway, we carry a bunch of filtration stuff for distilleries. Happy to talk to anyone about filtration and their product.

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We do a white rum that is treated with powdered softwood carbon for decolorization that requires .1-.22 to remove the gray haze induced by the PAC.  The PAC we use looks like laser printer toner.  I’m sure this has to do with nominal vs absolute ratings - but makes me feel that it doesn’t necessarily hurt to go tighter - assuming you are using two-stage with a pre-filter.

We use the same .1 and .22 with aged spirits - with a 1 or 5 micron prefilter.  Honestly I’ve thrown out cartridges long before they have clogged up, just because I’ve felt I’ve got my money’s worth out of them - and I get paranoid after using them for a few months.

I am of the camp that feels sub-micron filtration really gets you a “sparkle” that really coarse filtration does not (5-20 micron). The decolorization work we did was an eye opener in terms of filter micron ratings.  Even with a decent 1 micron filter - staring down through 200 gallons in a tote - it was obvious.

We used to do a triple cartridge setup with a really coarse initial filter - but came to the conclusion it was a waste of time.

Unless you are going out of your way to kick up barrel char and jam it through t  filters - cartridges last a long long time.  Exception being the decolorization - where we go through multiple carts per batch.

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This just in...

I usually use a mori gravity filler with an inline .2 or .5 micron DOE cartridge filter.  I pre filter my batch tanks with a bag filter to remove visible stuff (doing botanical infusions, or char).  But one of my bottles is opaque ceramic, so no way to tell the bottle is full on the gravity filler.  With 3 people we are fast, yes sometimes faster than 750ml out of the gravity filler.

So I recently got an xpressfill volumetric filler, which fills by time.  Set the time and it will fill for that duration.  I connected the same .2 micron DOE cartridge filter before the xpressfill. 

Here's the twist ending:  after filling about 1600 bottles, the fills started to come up short.  Gradually building from a few ml to half a bottle short.  Which was not discovered until over 1000 bottles were short filled.  Because heavy opaque bottle.  I only discovered this because there was too much product remaining in the tank.  Yikes, and a fun way to spend a day, opening sealed cases and bottles to refill them to correct volume on the gravity filler.

I traced the underfilling issue to the .2 micron filter by process of elimination.  The filter looked almost as pristine white as when new.  It seems the pump on the xpressfill is slowing down with the tiniest additional pull from the barely used filter.  This is completely unexpected because I previously used an xpressfill for a few years with a .5 micron DOE cartridge inline.  So apparently going from .5 to .2 micron is a big no for the xpressfill volumetric filler.

btw, I used that same .2 filter to finish the opaque bottle run on the gravity filler without issue.

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Ah ok - sucking through a filter is a lot harder on the pump than pushing.  I'm talking about tank-to-tank filtering prior to bottling.  And timer fill is going to be far more sensitive to changes to input flow rate.

We use a tall bottling tank, we need to adjust the fill time of our volumetric over the course of the run as the level in the tank falls.  It's most noticeable once the level falls below the level of the filler.  We picked up a Mori just because of how frustrating the fill rate adjustments were.

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6 hours ago, Silk City Distillers said:

Ah ok - sucking through a filter is a lot harder on the pump than pushing.  I'm talking about tank-to-tank filtering prior to bottling.  And timer fill is going to be far more sensitive to changes to input flow rate.

We use a tall bottling tank, we need to adjust the fill time of our volumetric over the course of the run as the level in the tank falls.  It's most noticeable once the level falls below the level of the filler.  We picked up a Mori just because of how frustrating the fill rate adjustments were.

Sucking and pushing are the same, provided it is the same pressure differential. And regular filters should not be run at high pressures, so sucking is a great way to do things, because you can't get above 1 atm pressure. Enolmatics work on this principle.

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6 minutes ago, Silk City Distillers said:

Most pumps we use can’t generate the same differential in suction as they can on the output side.

Enolmatic is vacuum, totally different scenario.

 

That is somewhat surprising, because when pumping spirits, most commonly used is a diaphragm pump. Those operate the same as pressure or vacuum pumps.

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You can pull through filters, but unless there's a compelling reason to do so, it is less efficient than pushing through them, and there are some strong arguments against pulling through filters.
Some positive displacement pumps can pull excellent vacuum—air diaphragm or peristaltic pumps, for example pull a very strong vacuum. However, even a "perfect" vacuum (which isn't possible to achieve on earth) is only about 14.7 psi. Most filters are not considered clogged until they reach about 35 psi of pressure differential

So, you definitely can pull through filters. It may work perfectly fine for some applications, particularly if the filtered product has very low solids and isn't likely to clog up the filter anytime soon. However, you will be leaving filter lifespan on the table since your filters will be clogged at less than half their usable life.

Also, finding vacuum leaks is no fun. I'd rather try to diagnose a leak under pressure than under vacuum.

Anyway, this is all academic. If you're filtering tank-to-tank and you're using a pump, you should definitely put the filters after the pump and push through the filter. Pulling through the filter increases the risk of pump cavitation and dry running. The enolmatic is a vacuum filler, so no choice there, and no harm, really. The upside for the Enolmatic vendors is that they get to sell more filters since the filters will necessarily be considered clogged more quickly. Since the Mori Filler is not a vacuum filler, we always put the inline filter after the pump.

3 hours ago, Silk City Distillers said:

Most pumps we use can’t generate the same differential in suction as they can on the output side.

If you do find that one of your positive displacement pumps is generating more vacuum than pressure, contact NASA immediately.

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On 2/27/2020 at 2:56 PM, MichaelAtTCW said:

You can pull through filters, but unless there's a compelling reason to do so, it is less efficient than pushing through them, and there are some strong arguments against pulling through filters.

 

I am sorry, but generally this is just not correct. The physics doesn't work that way. Filters work on pressure differential. The filter only "sees" the difference in pressure across the filter material, and doesn't know that, relative to outside air pressure, the pressure on the low side is at atmospheric pressure or zero or something in between. But the TOTAL pressure drop across the filter is what matters, so it IS true, that if you want to operate the filter at significantly LESS or MORE than one atmosphere differential drop, that pulling a vacuum on the low side without something to adjust pressure on the high side would not do what you want. I don't know what the STRONG ARGUMENTS are against pulling through filters, as far as the filter function is concerned, UNLESS that filter is meant to operate at something very different than one atmosphere (1 bar, 15 psi) differential pressure. If the concern is controlling flow, that is simply done by a flow control valve, same as if you pressurized with a pump. The latter will also allow you to drop the differential pressure down below 1 atmosphere, since the differential pressure across the filter and the flow rate are roughly proportional.

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22 hours ago, Silk City Distillers said:

I think we are saying the same thing.

Pump slip on most displacement pumps makes pulling that kind of vacuum a long shot.

Maybe, but just a semantical clarification:

Most all pumps people use are positive displacement pumps. Most such pumps would exhibit problems with pulling vacuum because their seals are not rated for vacuum. But plenty of them are, and the vacuum quality needed here is very poor: even a 1 psi will give you most of the pumping you need on the vacuum side, and almost all positive displacements pumps can do that. And of course, a diaphragm pump is a positive displacement pump, and generally can pull a fairly good vacuum. There is ONE exception, and that is a positive displacement pump that is designed to use the pumped fluid as the lubricant for the displacement element. This is the case, for example, in most impeller pumps used for things like wine, beer, or mash transfer. On the other hand, these are bad choices for use with spirits. Similarly, most momentum transfer pumps, also used for wine, beer, or mash transfer, will not pull a vacuum at all, and in fact, must be pre-primed before pumping. But again, these are even worse choices for use with spirits.

By the way, any self-priming pump is pulling a vacuum, although some are limited in the quality of vacuum, and some can only be run unprimed for limited amounts of time.

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3 hours ago, bluestar said:

I am sorry, but generally this is just not correct. The physics doesn't work that way. Filters work on pressure differential. The filter only "sees" the difference in pressure across the filter material, and doesn't know that, relative to outside air pressure, the pressure on the low side is at atmospheric pressure or zero or something in between. But the TOTAL pressure drop across the filter is what matters, so it IS true, that if you want to operate the filter at significantly LESS or MORE than one atmosphere differential drop, that pulling a vacuum on the low side without something to adjust pressure on the high side would not do what you want. I don't know what the STRONG ARGUMENTS are against pulling through filters, as far as the filter function is concerned, UNLESS that filter is meant to operate at something very different than one atmosphere (1 bar, 15 psi) differential pressure. If the concern is controlling flow, that is simply done by a flow control valve, same as if you pressurized with a pump. The latter will also allow you to drop the differential pressure down below 1 atmosphere, since the differential pressure across the filter and the flow rate are roughly proportional.

I understand filtration, and that filters work on pressure differential. I stand by what I wrote, and I'm not sure what you're claiming is "just not correct". Is it the word "efficient"? I guess that word isn't very precise. Sure, all other things being equal, you will get the same result given the same pressure differential regardless of whether that pressure differential is created by pulling through the filter or pushing through it.

However, every time I've dealt with one of our customers who is having issues with their filtration—like air leaks causing the filter housing to fill up with air from the atmosphere and slowing down their filtration—the issue has been on the suction side of the equation. It usually ends up being a process line leak or a bad gasket somewhere upstream. When they're able to move the pump further upstream, the problem goes away or the leak is found. For that reason I say again: unless there is a compelling reason to do so, it makes more sense to push through filters—either with pumps or gas/air—and every commercial bottling/filtration facility I've seen adheres to this principle unless they're using a vacuum filler.

Again, by relying on vacuum to pull through the filter you leave usable filter lifespan on the table since the greatest vacuum you could hope to pull is 29.9 Hg, and filters generally clog at 35 psid. Since you can never achieve 35 psid with vacuum alone, your filters will appear to be "clogged" more quickly. So, in that sense, any filter with a recommend changeout pressure greater than 15 psid is "meant" to operate beyond what vacuum is capable of.

Sounds like sucking through filters has worked well for you, so don't let me try to talk you out of it. However, if I were advising someone on setting up a standard tank-to-tank filter with a pump, I can think of no good reason to advise them to pull through the filter. You could do it and still control the flow through the means you outline—increasing the pressure at the inlet side and installing a flow control valve—but you could also just use a positive displacement pump upstream of the filter and completely avoid such byzantine measures.

 

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21 hours ago, MichaelAtTCW said:

I understand filtration, and that filters work on pressure differential. I stand by what I wrote, and I'm not sure what you're claiming is "just not correct". Is it the word "efficient"? I guess that word isn't very precise. Sure, all other things being equal, you will get the same result given the same pressure differential regardless of whether that pressure differential is created by pulling through the filter or pushing through it.

However, every time I've dealt with one of our customers who is having issues with their filtration—like air leaks causing the filter housing to fill up with air from the atmosphere and slowing down their filtration—the issue has been on the suction side of the equation. It usually ends up being a process line leak or a bad gasket somewhere upstream. When they're able to move the pump further upstream, the problem goes away or the leak is found. For that reason I say again: unless there is a compelling reason to do so, it makes more sense to push through filters—either with pumps or gas/air—and every commercial bottling/filtration facility I've seen adheres to this principle unless they're using a vacuum filler.

Again, by relying on vacuum to pull through the filter you leave usable filter lifespan on the table since the greatest vacuum you could hope to pull is 29.9 Hg, and filters generally clog at 35 psid. Since you can never achieve 35 psid with vacuum alone, your filters will appear to be "clogged" more quickly. So, in that sense, any filter with a recommend changeout pressure greater than 15 psid is "meant" to operate beyond what vacuum is capable of.

Sounds like sucking through filters has worked well for you, so don't let me try to talk you out of it. However, if I were advising someone on setting up a standard tank-to-tank filter with a pump, I can think of no good reason to advise them to pull through the filter. You could do it and still control the flow through the means you outline—increasing the pressure at the inlet side and installing a flow control valve—but you could also just use a positive displacement pump upstream of the filter and completely avoid such byzantine measures.

If you look at my reply, you will see that I did anticipate the some of the conditions you describe. Yes, if your filters require higher pressure differential than 14 psi, you can not use vacuum alone. However...

Let's talk safety: One advantage of a vacuum system for filling of higher-proof spirits (as opposed to beer, wine, or non-alcoholic beverage) is that it could be nominally safer. Yes, it will fail by cavitation if there is a leak, but you won't leak high-proof spirits and continue to run, which is an unsafe condition. And the leak does not have to be major, if pressurized, just enough to provide ethanol vapor. Also, if you are going to pressurize ABOVE 15psi with high proof spirits, you may change the safety requirements for your distillery, since you will need to have a pressure vessel with flammable materials.

Of course, part of why I do use them is because I do so with vacuum filler systems. And they have worked so well for me, that when we set up to filter spirits without bottling, we set up a vacuum based system as well. Yes, you must purchase filters that will operate efficiently below 14 psi, and you will not be able to extend the lifetime of the use of the filters by raising the pressure above that. Generally, this has not been a problem for us filtering spirits, I can see it being a definite problem filtering wine or beer. BTW, for most of the pleated filters we use with our spirits, while the maximum rated pressure is as high as 50psi, their nominal operating pressure is far less, typically below 10psi.

I stand by what I said, although I appreciate your clarification. By the way, I certainly agree with you, I would not set up to use vacuum on one side and pressurize the other, that was not what I meant to describe. I meant that if you are using filters that should operate BELOW 14 psi, you can use flow control to drop the pressure further.

Nevertheless, I think we can agree, that if you want to operate filters that require greater than 15psi differential pressure, vacuum is certainly not going to work for you.

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52 minutes ago, bluestar said:

If you look at my reply, you will see that I did anticipate the some of the conditions you describe. Yes, if your filters require higher pressure differential than 14 psi, you can not use vacuum alone. However...

Let's talk safety: One advantage of a vacuum system for filling of higher-proof spirits (as opposed to beer, wine, or non-alcoholic beverage) is that it could be nominally safer. Yes, it will fail by cavitation if there is a leak, but you won't leak high-proof spirits and continue to run, which is an unsafe condition. And the leak does not have to be major, if pressurized, just enough to provide ethanol vapor. Also, if you are going to pressurize ABOVE 15psi with high proof spirits, you may change the safety requirements for your distillery, since you will need to have a pressure vessel with flammable materials.

Of course, part of why I do use them is because I do so with vacuum filler systems. And they have worked so well for me, that when we set up to filter spirits without bottling, we set up a vacuum based system as well. Yes, you must purchase filters that will operate efficiently below 14 psi, and you will not be able to extend the lifetime of the use of the filters by raising the pressure above that. Generally, this has not been a problem for us filtering spirits, I can see it being a definite problem filtering wine or beer. BTW, for most of the pleated filters we use with our spirits, while the maximum rated pressure is as high as 50psi, their nominal operating pressure is far less, typically below 10psi.

I stand by what I said, although I appreciate your clarification. By the way, I certainly agree with you, I would not set up to use vacuum on one side and pressurize the other, that was not what I meant to describe. I meant that if you are using filters that should operate BELOW 14 psi, you can use flow control to drop the pressure further.

Nevertheless, I think we can agree, that if you want to operate filters that require greater than 15psi differential pressure, vacuum is certainly not going to work for you.

Makes sense, and under some conditions I may end up recommending filtering under vacuum to our customers. Sorry for the thread hijack @daveflintstone

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