What's the proper order of closed column blast? Open bottom valve till BHO drips (push air out) and then close it and blasting BHO till full? Then close top valve and wait 30-60 minutes? Then open slowly bottom one and collect?
The proper order is to pull a vacuum on the system, including the hoses, to remove all the air first. To have an explosion/conflagration, we need fuel, oxygen, and an ignition source. We have fuel and static electricity can provide an ignition source, so our best control is to isolate the fuel from its source of oxygen.
Check:
https://graywolfslair.com/index.php/diy-cannamed-production/9-4-extraction/9-4-9-alkane-extraction/9-4-9-2-propane-butane-extractions/9-4-9-2-1-butane-safety-and-social-responsibility
Before that you need to determine how much LPG you are going to pass through the material. On average I use about three column volumes, so a good place to start.
You need pre distill that much to load that much LPG into your storage tank. See this article using a Terpenator, but the technique is the same:
https://graywolfslair.com/index.php/diy-cannamed-production/9-4-extraction/9-4-9-alkane-extraction/9-4-9-2-propane-butane-extractions/9-4-9-2-3-butane-mystery-oil-removal-using-a-terpenator
I can't tell for sure from looking at your system what the different volumes are, but it looks like may need to make multiple runs to fully extract your column of material.
For injection you want everything cold, which includes your storage tank, column, and lower recovery tank, so as to keep the LPG liquid.
You are limited to how cold you can get your storage tank both its mechanical properties standpoint and from the standpoint of injection pressure. As the temperature of the LPG drops, so does its pressure.
One way to over come that is to use a gas mix with a lower boiling point, but that means that you will have to recover below that boiling point running passively.
You can also use a hot vapor boost to push the liquid like this:
https://graywolfslair.com/index.php/15-diy-equipment/15-25-hot-vapor-assist
Lastly you can use compressed nitrogen to push the LPG through and burp it off before starting recovery.
Another solution that I prefer, is a heat exchanger coil between the tank dip tube and the column, sitting in a dry ice slurry at the sublimation temperature of dry ice, which is about -78.5C/109.3F. That allows you to keep your storage/recovery tank at a higher temperature.
You can chill the storage tank in one dry ice slurry bath, the recovery tank in another colder one and, your column jacket another. If you have an injection heat exchanger, it would also have one.
After everything has normalized, and your storage tank at the temperature you want it at for direct injection or through a heat exchanger, you are ready to inject. I prefer to pull the vacuum before chilling, so as to remove any atmospheric humidity from the system before it reaches its dew point.
I prefer to inject two column volumes from the bottom, overflowing through a vent tube to the lower collection tank, with the lower column dump valve closed.
Your system isn't plumbed for it, so If you prefer to flood top only, check to see if you have a shower head at the top of your column to distribute the LPG more evenly over the top of the column.
With everything under vacuum and chilled, you shouldn't get instant vapor pressure once your injection starts, but with a top flood the vapors will rise to the top of the column preventing a full fill. Opening the bottom valve will relieve the pressure by venting liquid from the column bottom, but not full address the vapor at the top of the column issue.
In addition, soaking material without flow creates stagnant layers where the extraction slows to a crawl or stop. I therefore don't try to soak the column, but leave the bottom valve open and inject the LPG straight through. That resolves both the vapor issue and removes the stagnant boundary layers to speed up the process.
Recover by leaving your recovery tank in the dry ice slurry and set your collection tank in 110F hot water. Drain the column jacket and add hot water. I use 150F for column heat.
Merry Christmas!
