Vacuum Filtration Apparatus Setup

CAAB
Posts: 62
Joined: Fri Jul 12, 2019 2:49 pm

Vacuum Filtration Apparatus Setup

Post by CAAB »

UPDATE: 3/20/21

Bear with me while I go through a few edits here, it's going to take me a little while to get this all organized and written out.

The purpose of this post is to outline my current setup for a vacuum filtration apparatus for filtering naturally extracted tobacco (NET). I hope to share some of the discoveries I made along the way in case anyone is interested in using this method for filtering their NETs.

My interest in vacuum filtration is to learn what micron level PG and VG/PGA extracts can be filtered down to and what effect this level of filtration might have on flavor and how long an atomizer can last without needing a coil change.

Setup:

Having no background in this subject, I have built a filtration setup over a series of iterations. My current setup is a Joanlab Vacuum Filtration Apparatus and Oil-free Diaphragm Pump. https://www.aliexpress.com/item/1000042 ... 4064361pWR

Initially, I purchased the vacuum filtration apparatus by itself and attempted to use a handheld vacuum pump used for automotive purposes. I found that PG extracts could be filtered in this way very slowly down to roughly 11 micron, but involved a lot of hand pumping. VG/PGA extracts, being more viscous, could only be filtered down to around 25 micron, again, with much constant labor. For more than 1 or 2 extracts, it became untenable to me.

My next upgrade was a Harbor Freight Vacuum Pump https://www.harborfreight.com/25-cfm-va ... 61245.html

Immediately I found a problem with this pump, as it released a lot of oil vapor. I had to rig a vent hose to the pump in order to draw the vapor outside. Again, it was an impracticality for me to set this up each time I needed to filter an extract, as I had many extracts to work on for my initial rounds of testing.

Which led me ultimately to explore the Oil-free Diaphragm Pump. So while I initially attempted to reduce my costs for the vacuum pump, I ended up spending more in the end. The other pumps now needing to be sold to recover some of the expense.

I also purchased a Harbor Freight Air Pressure Paint Tank and filled the tank with dessicant, with an air stone at the bottom, and a hose attached to the air stone, leading to the vacuum pump itself. This allowed me to capture some of the alcohol vapor inside the tank during the VG/PGA filtration in order to prevent the solvent from reaching the pump itself.

I attached shut off valves to the tank so that I can keep the pump running while detaching the filtration apparatus without losing vacuum in the tank. In the picture, you can see two shut off valves because I can actually use 2 filtration apparatuses at once. I purchased a backup filtration apparatus after accidentally breaking a component of my first apparatus at one point. I also purchased a spare part for the first. So having 2, I thought I might as well use them both.

One thing I found necessary for the filtration apparatus is a viscous lubricant to place around the flask to form an airtight seal between the flask and the filtration element. Otherwise you lose a lot of vacuum to the imperfect seal of glass on glass: https://www.amazon.com/Haynes-Lubri-Fil ... B007QU2UAA

As for filtration disks, I used Whatman Cellulose Qualitative Filter Paper, 55mm. I purchased Grade 1, 4, and 5, which confusingly the numbers don't correspond to the filtration level. Grade 1 is rated at 11 micron, Grade 4 is rated at 25 micron, and Grade 5 is rated at 2.5 micron.

Removal of Tobacco Leaf From Extract

Prior to vacuum filtration, I always remove the tobacco leaf from the extraction solvent. I use a potato ricer to press the leaf in order to recover as much solvent as possible. I pour this over a fine mesh sieve to remove large particles. I then proceed to vacuum filtration.

Impressions On Filtering VG/PGA and PG Extracts

Not unexpectedly, I found PG extracts to be relatively easy to filter at 11 micron. In the case of individual tobacco leaf extracts, I was able to filter down to 2.5 micron right away without having to start with a larger pore size. However, in the case of pipe tobacco extracts, I found that I often had to start at 11 micron and then go down to 2.5 micron.

VG/PGA extracts are much more difficult to filter due to their viscosity. I always had to start at 11 micron before I could go down to 2.5 micron. In the case of pipe tobacco extracts in VG/PGA, it would take at least a whole day to filter 200ml of extract down to 2.5 micron, so for the sake of my testing, I determined that filtering VG/PGA pipe tobacco extracts down to 2.5 micron was not feasible.

Another note with VG/PGA extracts, is that a vacuum filtration apparatus will cause alcohol to evaporate, which increases the viscosity of the extract after each pass through the filtration apparatus. Heat helps the filtration process, but I avoided heating the extract, as I was concerned that heat at this stage would potentially have a negative impact on flavor.

Since the alcohol evaporates, it passes through the filtration apparatus, which is not healthy for the components. This is one reason I added desiccant in a pressure tank and had the line to the vacuum pump pass through this to capture at least some of the fumes.

Regarding the flavor of PG vs VG/PGA extracts or whether filtering down to 2.5 micron affects flavor or coil life, these are ongoing tests that I will report on as I make progress.

ORIGINAL POST:

Looking for a little advise. I recently purchased a vacuum filtration apparatus: https://www.aliexpress.com/item/33002025956.html

I was having problems forming a vacuum, the flask did not have a good seal, so I am using teflon tape to form a good seal on the glass.

I purchased a hand pump vacuum tool used for automotive purposes, however this was not working well with VG. So I upgraded to an electric pump: https://www.harborfreight.com/25-cfm-va ... 61245.html

I have a few problems. I still am getting a loss of vacuum over time. Do I try to seal the joints better? Or is that the nature of the beast?

Also, the vacuum simply has an on/off switch, so it just runs constantly until the VG/PGA extract starts boiling. I am worried I will lose a fair amount to evaporation. Is there a relatively inexpensive solution to have a pressure cutoff?

Is it bad for the pump to be turned on and off constantly? Is it bad to run continuously?

Another weird thing, I get a lot of vapor coming out of the pump. I've heard it could be vaporized oil. Or is it something else? Do I have to worry about oil contaminating the extract?
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Peter_Ramish
Posts: 91
Joined: Tue Jul 09, 2019 4:58 pm
Location: California

Re: Vacuum Filtration Apparatus Setup

Post by Peter_Ramish »

Welcome to the wonderful world of using vacuum in the lab ! :lol:

Don't worry, it's a headache for everyone, even the most experienced lab technician with the high dollar equipment is plagued by the endless fiddling of all the interactions. The darn setups just never seem to stabilize, it is an endless process of readjustments. They will all leak and draw down over time, that is the nature of the beast for home kitchen setups. In carefully engineered industrial and lab setups, then the leakage is very slow, but always occurs at some rate however small. You just have to decide if the pain is worth the reward. The major component is to understand what the goal is. If you are just using the setup to filter then I say the better route for NET is a centrifuge. If the goal is to reduce the solvent then high vacuum can be an excellent choice. So what is it you are trying to do?
CAAB wrote:
Mon Jul 13, 2020 4:16 pm
I was having problems forming a vacuum, the flask did not have a good seal, so I am using teflon tape to form a good seal on the glass.
I looked at your link to the one your purchased. It looks high quality and should seal OK. But if it takes teflon tape, then so be it. I have had to resort to sealants, but I use this:

Haynes Lubri-Film 1oz. Tube
https://www.amazon.com/dp/B00CTM3IFQ/re ... dFb2RMAK6V
CAAB wrote:
Mon Jul 13, 2020 4:16 pm
Also, the vacuum simply has an on/off switch, so it just runs constantly until the VG/PGA extract starts boiling. I am worried I will lose a fair amount to evaporation. Is there a relatively inexpensive solution to have a pressure cutoff?
Uhh, well yes the boiling is occurring as the pressure drops falling below the vapor pressure of the alcohol, so I guess you are just after the filtration, not solvent reduction. Humm, there again, more expensive equipment and complexity required: Pressure bypass plumbing, pressure sensing and cutoff at the pump switch, etc, etc... See my note at the end of this Reply for a possible solution with a reservoir tank.

With the vane pump you have there is no issue with switching it on and off. It will survive fine. The vapor you see out of the exhaust of the pump is undoubtedly condensed water and alcohol vapor. Just venting it to the room air is fine, watch out for sources of ignition as the alcohol is flammable.

You and I previously discussed a lot of these issues in the article: viewtopic.php?f=2&t=19

So we did cover a lot of this ground. I also mentioned, in some detail, these issues in: viewtopic.php?f=2&t=15

When I was in the "thinking stages" of this sort of setup I considered putting a large vacuum reservoir between the pump and the work. This would have two benefits: 1.) You could smooth the drawdown and regulate it better to a flask filtration task, and avoid some of the issues you have -2.) If using the setup for forced evaporation drying of water or Alcohol Solvents then the reservoir could be filled with common desiccants like activated carbon, zeolites or silica gel. This will preserve the life of the vane pump. You must replace that oil in your pump regularly as it is not now protected with the simple pass thu setup that you have at this time. The oil will contaminate over time and destroy itself. So in light of that, if you only require vacuums for filtration, not desiccant, then a aspirator setup might be better to avoid some of the issues:

SEOH Filter Pump Aspirator
https://www.amazon.com/dp/B00KI29HUE/re ... dFbJ97SXCW

Keep me posted on how you make out with all this: :roll:

PS: I considered using a pressure tank like this and loading it with ~10lbs of desiccant. So it's one more trip for you back to Harbor Freight hahaha :lol:

https://www.harborfreight.com/2-1-2-hal ... 66839.html

-and-
Dry & Dry (5 LBS Premium Pure & Safe White Silica Gel Desiccant Beads(Industry Standard 2-4 mm) - Rechargeable Silica Beads
https://www.amazon.com/dp/B01BLYLUSY/re ... dFbE51TYA9

You can replace the provided pressure gauge with a vacuum gauge and it will be a nice setup !

CAAB
Posts: 62
Joined: Fri Jul 12, 2019 2:49 pm

Re: Vacuum Filtration Apparatus Setup

Post by CAAB »

If you are just using the setup to filter then I say the better route for NET is a centrifuge.
I originally thought the centrifuge might be a little too complicated for me at this time, but here I am fidgeting with multiple pieces of equipment to make my setup work. I think I may, at some future date, look into centrifuges, but I am now for better or worse invested in the method I chose.
PS: I considered using a pressure tank like this and loading it with ~10lbs of desiccant. So it's one more trip for you back to Harbor Freight hahaha :lol:

https://www.harborfreight.com/2-1-2-hal ... 66839.html
I see what you are saying. I would be creating a vacuum in this chamber as well, between the filtration flask and the pump, which would result in a larger volume drawing down, so pump has to kick on less. Also, the desiccant would draw the water and alcohol.

I actually was looking to evaporate the alcohol anyway, so I am happy to see it evaporate, I was just concerned that the VG might be evaporating as well and the flavor components. So if boiling it in vacuum does not result in a loss of flavor, I am ok with that. At least, the level of vacuum this pump is able to achieve.

So do you think it's worth another trip to Harbor Freight, for the sake of filtration efficiency, pump longevity, and keeping fumes down?

BTW, as you are aware I am filtering PG and VG/PGA extracts for comparison. Today, I started with the PG extract. There was no boiling. I suspect the vacuum does not reach the boiling point of PG, whereas it was easily reaching the boiling point of PGA.

Another note, I am using Whatman cellulose filters. I started with grade 4, and jumped to grade 5. I can tell you that even under vacuum I suspect the VG/PGA extract would take days to filter 200ml under vacuum. So I am just going one round with grade 1 cellulose filters and calling it a day. I have so many extracts that I don't feel I have enough time this round to go through multiple passes using different grade filters.

Anyway, this whole round is a testing round, I started with Habana Daydream, as it was my least exciting extraction. I am saving that beautiful Padron 1964 Anniversary Series for last!

CAAB
Posts: 62
Joined: Fri Jul 12, 2019 2:49 pm

Re: Vacuum Filtration Apparatus Setup

Post by CAAB »

Oh and I forgot to ask:
You can replace the provided pressure gauge with a vacuum gauge and it will be a nice setup !
Do you have a recommendation for a vacuum gauge? I see lots of ports on the pressure tank. it looks like I could keep the valve on there with the two ports and just swap out the pressure gauge. I am guessing the other port on the other side is for the paint sprayer line, and I can ignore that.

CAAB
Posts: 62
Joined: Fri Jul 12, 2019 2:49 pm

Re: Vacuum Filtration Apparatus Setup

Post by CAAB »

Also forgot to ask, is it ok to run this pump for over an hour continuously?

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Peter_Ramish
Posts: 91
Joined: Tue Jul 09, 2019 4:58 pm
Location: California

Re: Vacuum Filtration Apparatus Setup

Post by Peter_Ramish »

I think you can find vacuum gauge on Amazon. I just did a search and saw nice ones for ~$7$ 13 another route is to look at the Herbal Weed Oil combo tanks and gauge setups like this:
https://www.amazon.com/s?k=vacuum+pump+ ... _ss_i_8_11
CAAB wrote:
Tue Jul 14, 2020 1:45 pm
So do you think it's worth another trip to Harbor Freight, for the sake of filtration efficiency, pump longevity, and keeping fumes down?
I would take a while and experiment with what you have now and try to dial it in. Like I said at the beginning, you can, if your are not careful, wind up throwing a lot of $Money around with projects like this.
CAAB wrote:
Tue Jul 14, 2020 1:45 pm
So if boiling it in vacuum does not result in a loss of flavor, I am ok with that. At least, the level of vacuum this pump is able to achieve.
No loss of flavor. That one of the benefits of using low temp vacuum dehydration. The temps are very low and there should minimal issues with loss of volitive oils or conversion of sensitive flavor molecules.
CAAB wrote:
Tue Jul 14, 2020 1:45 pm
Another note, I am using Whatman cellulose filters. I started with grade 4, and jumped to grade 5. I can tell you that even under vacuum I suspect the VG/PGA extract would take days to filter 200ml under vacuum. So I am just going one round with grade 1 cellulose filters and calling it a day. I have so many extracts that I don't feel I have enough time this round to go through multiple passes using different grade filters.
Well, there you go.. the whole filtration thing depends on surface area vrs amount of physical contaminates that will be trapped and therefor clog the pores as this unwanted material clogs the barrier. This leads to continuous degradation of the efficiency of the process as the "filtration" proceeds. Not to mention the product loss as each of these filter barriers fill with absorbed, retained material, and therefore represent a loss of the target product that you are trying to recover.

So after a few weeks of experimentation you will dial it in. But, I suspect, that even after you dial it in and become an 'old filtration pro' that you will then understand the engineering trade offs involved. Whether those trade offs let you have what you will call a "successful technic" or a "big waste of time and money".. well,.. you will just have to let that play out.

I don't mean to be too negative, as you can't go wrong having a vacuum pump around the lab, but it just might be that what you thought when you started that tasks the pump was good for will turn out, in fact, to be a task completely different. Still good, and a great piece of machinery to have around, but just not what you originally thought.

-Peter 8-)

CAAB
Posts: 62
Joined: Fri Jul 12, 2019 2:49 pm

Re: Vacuum Filtration Apparatus Setup

Post by CAAB »

Too late, lol. I picked up a pressure tank. I was concerned about the wear and tear on the pump, the alcohol fumes, and just the time it takes switching the pump on and off constantly.

I think I'll hold off on the pressure gauge for now, but it looks like I have to swap out some parts up top. I am thinking of having a simple in port and out port that can fit the type of tubing I have from the filtration apparatus.I am going to see if local hardware store has air line fittings that will work.

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Peter_Ramish
Posts: 91
Joined: Tue Jul 09, 2019 4:58 pm
Location: California

Re: Vacuum Filtration Apparatus Setup

Post by Peter_Ramish »

CAAB wrote:
Wed Jul 15, 2020 1:21 pm
I am going to see if local hardware store has air line fittings that will work.
I am sure they probably do. Also Harbor Freight has a surprising number of the lines and fittings Since you went ahead on the tank, then why not pick up some Silica Gel? It will go a long way to protect the oil & the pump. Also get an extra gallon of pump oil.. hahaha you are in it now ! no turning back ! I love to see someone spend money, good for the covid economy :D

See the article viewtopic.php?f=2&t=22
there are two important articles to download:
  • Vacuum Pumps -1.pdf
    Vacuum_Pumps- 2.pdf
So which tank setup did you go with? And you will probably have to fabricate some sort of diffusion screen and way to route the incoming contaminated air up from the bottom of the tank thru the gel. Let us have some pictures of your setup when you get the chance, I would be interested to see how it evolves.

CAAB
Posts: 62
Joined: Fri Jul 12, 2019 2:49 pm

Re: Vacuum Filtration Apparatus Setup

Post by CAAB »

So funny story. I went into Lowes today with the pump, the filtration apparatus line, the lid to the pressure vessel, and 0 clue what I was doing.

I eventually ended up in the plumbing section for half an hour sort of pushing things against each other until this guy comes out of nowhere and asks if I need help. He takes one look at my cart and says, "oh, a vacuum pump. Are you doing extractions?"

Turns out the guy lived in Colorado helping out with unspecified "extractions." I'll let you fill in the blanks. So he hooks me up with copper line, fittings, the works. It's perfect. I have yet to assemble it. Probably over the weekend.

He said it's good I have the tools to work with the copper, because I'm probably going to tweak my system as I go. Sound familiar? Hope I'm not in for it too bad. Just want to get through the PG - VG/PGA comparisons this year, and worry about any kind of (hopefully small) upgrades within 1-2 years.

Anyway, I got some silica desiccant for flowers. Starting out with 3 lbs, see how that works. Will keep you posted on progress and if I get it nailed down, some pictures...

CAAB
Posts: 62
Joined: Fri Jul 12, 2019 2:49 pm

Re: Vacuum Filtration Apparatus Setup

Post by CAAB »

Huzzah, getting a lot more vacuum now with that pressure chamber. It adds capacity, so I am not recharging a tiny filtration apparatus constantly.

Getting a sizable air leak around the filter itself, where the two pieces of glass are clamped together. I am guessing there is not much I can do on that front. I added two clamps on either side to help strengthen the seal. But I think that's just going to be a point of weakness. Otherwise everything is pretty tight.

I am able to filter PG extract down to grade 5 cellulose, around 2 micron, with the new setup. I may go back to the VG/PGA extract and see what happens with a grade 5.

I am still getting a lot of condensation in the pump exhaust. I am thinking of putting a pipe back inside the pressure chamber so the air has to flow closer to the bottom of the tank where the desiccant is. I am also considering adding more than 3 lbs desiccant.

I am also thinking at a later point to add something between the filtration apparatus and the pressure chamber, something that could distill the vapors, whether water or alcohol, and collect them before they reach the pressure chamber and pump.

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