Top Flood or Bottom Flood Extraction? Bi-Directional. June 05 2017, 1 Comment

There is a lot of debate on the decision to perform a top flood or bottom flood extraction method. Some might say bottom flood is "too complicated" or "unnecessary". Maybe even that it does not work as well. If the bottom flood method was performed properly they would not be saying anything of the sort.

However, there has always been a correct assumption that the oils and solvent should be washed down the column assisted by gravity. Nonetheless a bottom flood should be used to fill the column with solvent and saturate the material properly for a reliable, high yield extraction. This is where the two methods (top flood and bottom flood) can join forces to use the same force, gravity, to evenly saturate the material and wash the oil and solvent down to the collection chamber afterward.

In order for oils to be dissolved from plant material, the material must be saturated. With dry plant material packed in the column tightly and/or unevenly liquid solvent does not penetrate the plant material evenly when gravity's effects come into play. The liquid will move through the path of least resistance, meaning if there is no opposing force the liquid will move down towards the collection pot without trying to spread out and permeate the material. The oils will only get picked up if they come into contact with the liquid solvent and a wider diameter column can make this problem worse.

This can be easily demonstrated with a pot of dry soil and some liquid water ("the universal solvent"). The dry soil is somewhat "hydrophobic" and repels the liquid water. When quickly washing water over the top of the pot, the water gets pulled down by gravity and flows down the path of least resistance. This washes down any loose particles in the path, opening it up, lessening the resistance of that path. You could imagine how a lot of water could go through the container onto the ground without really achieving it's purpose (wetting down the soil). If the container of dry soil was pushed down into a bucket of water, the water would quickly saturate it because of the force of gravity keeping it in contact with the soil even though it would try to repel the water. This would ensure an even and full saturation of the soil in a quick period of time with very little or no water wasted.

Filling liquid solvent into the plant material column from the bottom to the top ensures a full and even saturation of the product in a quick manner with an easily measurable amount. This enables the extraction operator to determine a more precise amount of solvent to be used, allowing recovery times to be reduced while yield is maximized. Washing too much solvent through the column can lead to longer recovery times and possibly more undesirable compounds being picked up by the solvent. 

A benefit of having the "liquid" line, which is overlooked in some cases, is the ability to drain the column with the line at the top open to the collection pot. This allows for almost all of the solvent in the column to drain down to the collection pot. When the top of the column is sealed off, the liquid draining down is not going to make it very far. For example: when a finger is placed on top of a straw full of liquid and the straw is lifted out of the liquid, it may be noticed that the liquid stays in the straw until the finger is removed from the top.

When allowing the solvent to drain from the material column, all of the oil-laden solvent does not drain down to the collection pot. With a Bi-Directional Modification, a top rinse can be performed to wash this oil left behind down the column by top flooding the column through the bi-directional valve up the "liquid" line with the "liquid" valve closed and the "dump" valve open. This also has the benefit of washing free any oil that could have possibly made its way into the "liquid" line.  

A method implementing a bottom flood followed by a top flood is the most efficient method of extraction that can be performed on dry plant material to ensure the fastest, most precise, and highest yielding extraction possible.

Check out our Bi-Directional Modification Kit and/or give us a call at (970) 682-6710 to add it to your system.

Fire Safety Guidelines Regarding Hydrocarbon Solvents May 23 2017, 0 Comments

Guidelines are prepared by Terpp Extractors technical staff to assist users in reading and understanding safe practices, however, are no formal interpretations issued. Any opinions expressed are the personal opinions of the author(s), and do not necessarily represent the official position of Terpp Extractors. In addition, the guidelines are neither intended, nor should be relied upon, to provide professional consultation or services. The (AHJ) Authority Having Jurisdiction will determine the facility requirements for operation of extractors.

Butane is classified as Liquefied Petroleum Gas (LPG) by the International Fire Code (IFC), which invokes NFPA 58: Liquefied Petroleum Gas Code.

When working with any flammable solvents a potentially explosive environment can be created in the area. This stresses the importance of safety procedures that should be implemented to prevent potential accidents. These guidelines only pertain to fire/explosion hazards and do not encompass all safety procedures that should be integrated into the extraction process.


(1) Do not allow the flammable solvent to mix with air (oxygen).

  • A seal (such as a gasket) that does not leak under vacuum may leak with positive pressure.
  • A positive (air or nitrogen) pressure test should be performed on the entire closed loop system each time the extractor is assembled to ensure leak-free operation. If air can leak from the extractor, gas can leak out during operation and mix with air to possibly become an explosive mixture in the area.
  • A full vacuum should be pulled on the entire closed loop system before solvent introduction to ensure an oxygen-free environment is maintained in the system. Without oxygen, combustion cannot occur even in the presence of an ignition source.

(2) Eliminate all potential ignition sources in the environment.

  • Only intrinsically safe equipment should be allowed in the environment.
  • All electrical equipment should be rated for Class 1 Division 1 or Division 2 environments.  Electrical devices designed for laboratory use in a Class 1 environment will carry a NEMA 7 rating.
  • Ancillary equipment should be located in a separate room.
  • Take steps to reduce static electricity.
  • N-Butane's autoignition temperature is approximately 550 degrees Fahrenheit.


(3) Install an appropriate ignition-proof hazardous exhaust system.

  • The facility must provide adequate ventilation/exhaust as determined by the Engineer of Record in order to maintain the local atmosphere below 25% of the Lower Explosion Limit (LEL).
  • N-Butane's explosion limit ranges from 1.6% - 8.4%.
  • At a concentration in air lower than the LEL, gas mixtures are "too lean" to burn. Butane gas has an LEL of 1.8%. If the atmosphere has less than 1.8% butane, an explosion cannot occur even if a source of ignition is present. Flammable limits, like flashpoints however, are intended as guides not as demarcation lines between safe and unsafe.
  • Butane is heavier than air which means it can collect in low spots in the area.
  • If ventilation is inadequate, vapors can settle and collect in low areas like sumps, sewers, pits, trenches and basements. The vapor trail can spread far from the liquid. If this vapor trail contacts an ignition source, the fire produced can flash back (or travel back) to the liquid. Flashback and fire can happen even if the liquid giving off the vapor and the ignition source are hundreds of feet or several floors apart.


(4) Employ a hydrocarbon leak detector during operation.

  • An alarming hydrocarbon leak detector rated for the LP-Gas solvent being utilized should be used throughout the entire extraction process to ensure the local atmosphere is maintained below 25% of the LEL. 


(5) Appropriate PPE should be worn at all times.

  • Refer to LP-Gas solvent's Material Safety Data Sheet for more detailed information.


(6) Always have a fire extinguisher in the area.

  • A fire extinguisher should be available in the area at all times.

New Product Requests April 07 2017, 0 Comments

Want a product but can't find it on the website? Have you already called the office to ask if we carry it?  

We are looking at introducing many new products, and if there is anything you would like to be put on the list for review please comment below. These suggestions can be anything relating to oil extraction equipment or Terpp Extractors related products.

New products are open for discussion. Let's hear it.


Tech Topics February 10 2017, 1 Comment

What topics would you like to read about? We want your input! Please comment!

New Tech Blog - Comments Welcome February 10 2017, 3 Comments

Want to talk about tech with us? Have questions? Looking for helpful tips and tricks to start your operation off right? Want to grow with your demand, but don't know if you need bigger equipment or just need to update your technique?  Maybe you have some ideas or experiences you would like to share?

Well, we are proud to introduce our Tech Blog. We hope that it will become a great resource of information to advance the community.