March 22, 2014

Frequently Asked Questions About Purging BHO

March 22, 2014
bho butane hash oil extraction purging vacuum oven

bho butane hash oil extraction purging vacuum ovenProperly purging butane hash oil (BHO) is a vital step to making BHO that a lot of people either overlook, or don’t take serious enough. No one wants to consume BHO that is not properly purged for health reasons, and because it tastes horrible. A lot of people can get their hands on quality flower/trim, and a lot of people can blast it with butane. But where a rookie BHO maker is separated from an expert BHO maker is during the purging phase. If you want to step up your BHO game, get a quality purging setup!

Below are frequently asked questions and answers about BHO purging, supplied by my friends at Cascade Tek. They know more about BHO vacuums and ovens than anyone else on the planet right now. I encourage everyone to check them out if you want to know more about obtaining the best BHO purging set up around:


  • What is a vacuum oven?
    • A vacuum oven is an appliance that heats a sample at less than atmospheric pressure. When heat is applied, molecules move faster and are more likely to off gas from the product. By reducing the pressure, trapped molecules are able to off gas and be pulled out of the chamber by the vacuum pump.
  • How do I know if I really need a vacuum oven?
    • A vacuum oven will increase throughput by accommodating larger batches. If you are looking at ramping up production, a vacuum oven is probably for you.
    • You need a vacuum oven if you want to produce a more consistent product because heat uniformity is much more precisely controlled.
    • A vacuum oven will help you reduce cycle time by adding the correct about of heat and vacuum.
    • A vacuum oven will also significantly reduce the amount of babysitting required when processing.
    • You DO NOT need a vacuum oven if you are new to processing and just getting started.
    • You DO NOT need a vacuum oven to purge BHO for personal use.
    • You DO NOT need a vacuum oven if you aren’t sure how the process works.

If you answered yes to the items above, you should reconsider processing.


  • Why do some vacuum ovens cost $1,500 and some cost $15,000? What is the difference?
    • Just like cars, electronics and jewelry you get what you pay for in a vacuum oven. Cascade TEK vacuum ovens are the standard in research labs, Aerospace production, medical device manufacturing and electronics processing because they are robust and well-engineered.
    • Cascade TEK ovens are made in America from sheet metal to final assembly.
    • Cascade TEK ovens are industrial grade for professional operation.
  • I see some vacuum ovens with wire racks. Why do your ovens have Solid Shelves?
    • Wire racks work well in a convection oven where warm air is moving around the chamber warming things. In a vacuum oven, there is no air so heat is not transferred by convection.
    • Cascade TEK uses solid shelves to more efficiently transfer heat from the walls of the oven to your product. This reduces hot spots and creates more even, stable heating.
    • Cascade TEK uses aluminum instead of stainless steel because aluminum is a much more efficient conductor of heat.
  • How can I tell how hot my product is when it is in the vacuum oven?
    • You can really only tell with a thermocouple or wireless heat probe that is touching the product.
      • The controller is reading the temperature of the control probe in the oven, not your product. Many cheap ovens have the control probe buried inside the wall somewhere. This is far away from your product. Cascade TEK keeps the probe of the TVO-2 in contact with the shelf so you know what the actual shelf temp is.
      • Using an IR sensor through the door gives you the temperature of the glass, not your product.
      • Backfilling the oven with air and then using the IR probe measures the heat of the air around the product. This will change when you pull a vacuum again.
  • I found a vacuum pump at Harbor Freight. Can I use it with your oven?
    • Yes, but don’t. These HVAC pumps may seem like a bargain but they are certainly no value.
    • These pumps are oil-sealed, dual stage rotary vane pumps which are very common in industry. They are not the right choice for solvent extraction or consumable manufacturing:
      • Everything that is coming out of the vacuum oven goes through the oil that is lubricating the pump. In the solvent extraction application, this means that solvent will be constantly breaking down the oil. These pumps are a disposable commodity in the BHO business.
      • Oil from the pump can back stream up the lines to the oven. These hydrocarbons can settle on your product causing contamination.
      • These pumps emit an oil mist that will exhaust into your working environment and deposit on your other equipment and surfaces.
  • What kind of pump do you recommend?
    • Cascade TEK recommends a chemical duty membrane pump for BHO extraction. These pumps are made to chug through solvents and contain no oil that could contaminate the process or environment.
  • Is a bigger vacuum pump better?
    • Bigger isn’t always better. Too much vacuum (pressure that is too low) can off gas molecules that you want to keep in your product like Delta-9 THC.
    • The size of the pump is secondary to the type of pump. We recommend a chemical duty pump that is not negatively affected by exposure to solvents.


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