Hee, hee, hee, snicker, snark, snort! Check out this 150F Closed Wash Decarb paper by Ichiban Crafter!
Hee, hee, hee, snicker, snark, snort! Check out this 150F Closed Wash Decarb paper by Ichiban Crafter!
There is a lot of discussion about which recovery pump is best suited for our application and my first thought is to ask which one of our applications?? Different processes and budgets have different needs.
While our industry got started using pumps designed for refrigeration recovery and from those humble beginnings different pumps evolved, in our legitimacy we now have available to us pumps developed by the petrochemical industry specifically for transfer and compressing the liquid hydrocarbons like propane and butane that we use in our processes.
Amidst the new plethora of options, we are also faced with exorbitant claims, reminiscent of the “This is primo shit man” claims prior to legalization and lab analysis, soooo let’s review the universal laws governing pumps, and discuss design features.
The pumps typically used in our industry are displacement pumps, which expel a given volume with each stroke of the piston.
The amount of actual gas within that volume depends on its density and thus the volumetric efficiency of the system, as well as the pressure on the pump intake.
Volumetric efficiency relates to the systems resistance to the flow of gas on the intake side and is influenced by intake pressure, line and port sizes, as well as valve size and timing and pump speed. That is different for each pump.
While the internals of the pump head may not be easily examined, one measure that is typically visible is the discharge port and line size. As a rule of thumb, for a given cfm there is less resistance to flow in a big line than a small one, so look at both line and port sizes. Some smaller ports are bushed up to accommodate larger line sizes, but the small port itself remains as a restriction.
Vapor density is a variable that affects not only the volume pumped, but the horsepower required to do so.
If we look at a pumps free air cfm rating, the intake to the pump is at atmospheric pressure, or about 14.7 psi absolute and there is no resistance to flow on the discharge side beyond line friction and static pressure from bends and elbows in the internal piping.
Under those circumstances, each stroke of the piston pushes its displacement volume from the cylinder out through the discharge port, so ignoring volumetric efficiency, if the piston diameter and stroke of the pump was 1 cubic inches and it was running at 1725 RPM, then total cfm would be 1 X 1725, or 1725 cubic inches per minute discharged. 1725 cubic inches is a cubic foot so output would be 1 cfm.
Now consider what happens when the pump intake is below atmospheric pressure. 14.7 psi is about 29.92” HG/760K microns and gas laws tell us that density and pressure are directly proportional, so if the atmospheric pressure on the intake is half the 14.7 psi or say 14.96” Hg/380K microns, then the density of the vapors in the cylinder will be half, so each stroke of the cylinder will discharge half the vapor.
Conversely, if the intake is under positive pressure, the opposite is true. Each stroke of the piston will deliver a proportionately higher volume.
When the vapor being pumped is from a boiling pool, when the liquid turns into vapor, it absorbs the latent heat of vaporization, which drops the temperature of the boiling pool and slows boiling to a crawl as it approaches its boiling point under vacuum.
The way to offset that and maintain recovery speed, is to replace the btu’s lost to vaporization so as to maintain atmospheric to positive pressure on the pump’s intake.
That brings us to what happens on the discharge side of the pump. The gas discharge will be at a higher temperature than the intake because of heat of compression and the gases physical contact with the hot pump. Unless we remove that heat, the tank pressure on the discharge side of the pump will rise and though the pump with an unfettered intake will still put out one cylinder volume per stroke, the back pressure on the discharge side will require more horse power to do so.
Once the horsepower required exceeds the amp rating of the motor, the motor will overheat and trip the overload. Increasing horsepower will solve the back pressure issue, but will not add to the pumps output, only an increase in volumetric efficiency or rpm will do that.
Some two cylinder compressors can be run either single stage or double stage to address the back pressure issue with existing horsepower. In single stage both cylinders discharge directly to the exhaust and in double stage, one cylinder discharges to the intake of the second cylinder, which discharges to the directly to the exhaust, so that the pump puts out about half the volume, but at twice the pressure using the same horsepower.
Opaline Silica might just be the best thing since sliced bread. It is a granular absorbent containing hydrated silica (Amorphous Opaline Silica) and bentonite brought to us by the same great people at Oil-Dri (Pure-Flo, Agsorb, etc) who mine some of the industry's favorite filtration media such as B80.
“Diatomaceous shale is altered rock primarily made from the fossilized remains of tiny, aquatic organisms called diatoms, along with minor amounts of clay minerals. Over millions of years, these small organisms collected in the sediments of rivers, streams, lakes, and oceans, and then became deeply buried and altered into hydrous opaline aluminosilicates. Diatomaceous shale is very fine and porous.” -OilDri
“In the Gusev crater of Mars, the Mars Exploration Rover Spirit inadvertently discovered opaline silica. One of its wheels had earlier become immobilized and thus was effectively trenching the Martian regolith as it dragged behind the traversing rover. Later analysis showed that the silica was evidence for hydrothermal conditions.” Ruff, S. W., et al. (2011)
What is it:
“[F]rom Taft, California is a Hydrous Aluminosilcate (SIC) mineral. Its low bulk density and high absorptivity allows higher liquid holding capacity. Our mineral processing maximizes the granule’s micropore space. AGSORB® heat treatments impart a hard, inert granule with a high resistance to attrition. The unique properties of this mineral make it harder in its natural state than other RVM products.” -OilDri
Chemical composition by weight:
80% SiO2, 9% Al2O3, 8% H20, 2% Fe2O3, 1% Other salts
RVM (Regular Volatile Material)
LVM (Low Volatile Material)
How is it different from other filtration media?
The two biggest differences from the processor’s standpoint are ease-of-use and required operating pressure. Opaline silica is granular and not a cumbersome powder, so you won’t make a huge mess every time you pack a filter. For that same reason, you no longer have to worry about inhaling dust (and hydrated silica does not cause silicosis). You don’t need to pre-bake your filtration media,* you don’t need to pre-wet it either. You don’t need to pack it down, and you don’t need a DE/Celite layer, just a 5-micron filtration paper, and retention ring.
However, according to extraction guru Photon Noir “depth filtration is important to achieve stringent particle removal and reasonably fast flow. This can be achieved using a strong screen supporting the media’s weight above some cotton wadding, filling the space between the screen and another sheet of screen over the outlet hole… not packed too tight, but tightly fitting around the sides, where dust would like to channel”.
He also recommends baking your media before use but when we did that we experienced lower yields. MediaBros recommends not baking your media prior to use.
What are its capabilities and limitations?
This is not the best filtration media for water-clear. However, when used properly it can remove a bulk of your color. Water clear can be achieved in some instances depending on the starting material and whether or not you are recirculating.
How do I use it?
Where can I get it?
RVM is mined in Taft, California by Oil-Dri/Agsorb and it comes in 3 different mesh sizes. For processing, we will be using either the 16/30 or 24/48 mesh size To purchase from OilDri, you need to set up an account and order 1000lbs at a time. If you’d like to try a smaller amount you can purchase from multiple sources such as MediaBros or FatDogCBD.com (cheapest option). Oil-Dri makes lots of products that look very similar, make sure you’re getting “RVM” from their mine in Taft, California AKA “RVM-T”
Make sure to steer clear of any absorbents that contain “cristobalite, a crystalline form of silica that is listed as a class 1 carcinogen and is very common in clay deposits, especially bentonite, so it is good to warn folks not to just go around trying any old high silica clay media” - Photon Noir
The high flow rate of the opaline silica allows you to set up an AODD (air-operated dual-diaphragm) pump to pump liquid butane (or another hydrocarbon) from your collection vessel back through your CRC (color remediation cartridge) over and over until the solution reaches the desired color. On large (multi-column) batches you can recirculate while you recover.
Make sure to order a pump with PTFE diaphragms. The one I picked out has ½” inlet and outlets and a max operating pressure of 100PSI which is 2x-3x what our system will ever reach with opaline silica. Here is a nice option, and another and Sambo Creek makes some that will work as well. Make sure to get the model with metal housing. These pumps run at about 12-15pgm which is higher than our ideal flow of 1GPM, but you can just keep passing the solution over your material until the desired results are obtained.
*The RVM is 9% H2O by weight and baking might help pull color, however, I tried baking media before use and saw diminished yield. Media Bros suggests not baking while Photon Noir suggests baking, these two are great sources for information and in this instance, they have conflicting views. I encourage you to try both and report back with your findings.
On that note, shoutouts to:
Photon Noir, Media Bros, Tom from OilDri, Cyclopath, Dred_Pirate, and ColombiaBeneficial.
While I first shared the Terpenator design on 2-7-2011 on both SPR and IC Mag, and subsequently the fully automated Mk II, it was really the manual Mk III shared on 9-19-2012 that gained a foot hold and went viral.
It was also the design that I subsequently expanded into the Mk IV and V and was the basis for numerous emulations by others using the general Tri clamp sanitary fitting design.
The Mk III holds about 150 grams of plant material in its 1 ½ X 24” column and produces about one ounce of concentrate per run, making it an excellent size for personal use, but is fast enough that we used it for bulk extraction before developing the Mk IV and V.
Between then and now, numerous process improvements have evolved so it’s time to retire the older Terpenator design and move on to the Mk III Evolution embracing the process innovations by me and others. The same upgrades could be made to a Mk IV and V, but I will focus only on the Mk III as support to individual medical cannabis patients and small groups sharing equipment.
The Mk III design itself was simple and straightforward, lending itself to both passive and active recovery, and the Mk III Evolution follows that tradition so as to keep costs minimal. I’ve also designed some ancillaries to work in concert with the Mk III, which are frosting on the cake for those who elect to build a Mk III or larger system for themselves.
Unlike Nitrogen, which must be burped with attendant LPG losses, pressurized LPG can be recovered along with the chilled tank with no burping and attendant losses required.
Here is a conceptual showing an assembly of the above components , plus some I will share shortly:
by Mary Babitz, Founder – Cascade Sciences
In my years of working with engineers, the most interesting remains the Aerospace Contamination Engineer. Working with them on vacuum “bake-out” systems, I learned just how important contamination risks are to NASA and other companies that send things into space.
There’s the obvious… satellite/rocket components, and electronics that perform in the vacuum of space must be outgassed prior to launch. All trapped gasses, moisture, molecules must be completely purged here on earth as not to outgas once in orbit and risk damage to sophisticated electronics. There are no do-overs once launched.
But the NASA Contamination Engineers take it a step further. They measure rates and types of materials outgassing off the product during vacuum bake-outs. They want to be able to know that if Mars Rover rock samples show evidence of Yellow #5 food coloring, Earthlings brought it, because it was identified in an outgas analysis during a Rover component bake-out.
Purging solvents of cannabis extracts is a decontamination process all its own. The end product will be ingested/consumed into the human body, so what are some of the potential contamination risks associated with this equipment and process? Here are a few that come to mind:
Oil Rotary Vane Vacuum Pumps = Potential Oil Contamination
Agilent DS-602 Rotary vane vacuum pump
These vacuum pumps are popular due to their lower cost, rugged performance and deep ultimate pressures, but due to how oil molecules behave under vacuum, rotary vane pumps are not appropriate in clean processes like food, pharma and cannabis. The oil that keeps these pumps humming collects outgassed material, water, etc.. and dirties over time, just like the oil in an automobile. Ick.
The biggest risk is a “back-streaming” event, where a pump in the off position + a chamber under vacuum will rush to equalize pressure by sucking air up thru the filthy pump exhaust and splatter oil mist inside the oven. Back pressure valves try to prevent this, but still – it’s a dirty idea to begin with.
Solutions - A better choice would be oil-free pumps such as scroll pumps, diaphragm pumps. If you must use an oil-rotary vane pump, at the very minimum a foreline trap should be installed at the inlet to the oil-filled rotary vane pump. This filter will potentially catch hydrocarbon molecules that could forcibly backstream into the oven or catches random dirty oil molecules that free-range around the system during molecular flow.
Agilent KF-25 Fore line Trap
Agilent IDP-7 Dry Scroll Vacuum Pump
If you don’t have an exhaust mist filter on your rotary vane pump exhaust, consider that as well. The oil mist that is filling the ambient lab space is in the same air space the vacuum oven will draw from vent.
Agilent Oil Exhaust Filter
Heated Shelves = Potential outgassing contamination of solders, epoxies, silicone
Because temperature control is tricky under vacuum, some manufacturers will offer heated shelves. At lower-tier price points, a heated shelf can consist of coated wires, heating elements, solder material, (typically lead and tin), possible epoxies, etc… all used to fasten a heating element to the bottom of a shelf. Seems fine enough, but once heat and vacuum are introduced, the materials used to construct the heated shelf, can also outgass inside the oven, potentially exposing the product to a variety of contamination risks.
Properly designed heated shelves are actually hermetically sealed heated platens, a solid chunk of SST or Alum with heating or cooling elements machine grooved out of the center, hi-vac leak tested to allow zero exposure of any contamination to outgass into the product inside the oven.
Door Gaskets = Potential Outgassing of absorbed waters, surfactants, silicones
Tragically, O-Ring seal failure brought the 1989 Space Shuttle Challenger to a horrific end. It’s ironic how such a small part can have critical impact on a process. It’s no comparison, but without a cured, low-outgassing door gasket, your vacuum process can suffer. Make sure the vacuum door gasket is cured prior to use and ask for material certifications to ensure your Viton or Silicone is pure.
Parchment Shelf Paper – Out gasing Silicone & Terpene Sponge
Parchment paper is paper + silicone. Terpenes dissolve silicone. During vacuum purging, terpenes are breaking down the silicone barrier and are being absorbed into the leftover paper – potentially losing valuable terpenes.
PTFE Solution – PTFE (Polytetrafluoroethylene) material will not absorb purged product. It is often reusable. PTFE’s smooth, solvent proof, slippery surface prevents bacteria from sticking and embedding in PTFE surfaces. It also prevents unwanted absorption of valuable terpenes and botanical compounds from leeching out of the product and into the tray. PTFE also won’t break down in the presence of alcohols, terpenes, ethers, hydrocarbons, butane and propane.
When cleanliness matters, the devil is in the details. Attention to a few of these small details can make a bid difference to keep your process free from unwanted/unnecessary contamination.
Mary Babitz of Cascade Sciences