Vacuum Pump Test before distillation in spinning Band system

Hash and Stuff Distillation
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Hello Guys,

i have a question to the pressure in spinning band system.

Do you do vacuum pressure test (up to the limit of your vacuum pump before you distillate oil/extract in spinning band system)?

For the beginning of distillation i do a pressure test with an empty flask to the vacuum end of my pump (0,001 mbar). While i do this everything is fine. I reach the vacuum limit of my pump. I do this to have the safety that my Pump is ok and that i dont have any leaks. I have a vacuubrand RZ 6 Pump with a digital Controller.

After that i feed my cold trap with liquid nitrogen. I change my pump oil in regular times. I also change all cover seals for each distillation. So there should not be any leakage.

But as i do the vacuum test with the same flask filled with extract (oil) in it the pressure only gets to 0,053 mbar not 0,001 (the temperature in the pot is room temperature → so no heat while the vacuum test). Is there anything which disturb the pressure at this moment? The oil have many bubbles at this pressure. The Oil was decarboxylated before.

I often read in this forum, that you have to reduce the pressure in steps. For terpenes you use for example 0,3 mbar and for cannabinoid fraction the hole vacuum of your pump. So could it be that it is not good to do a vacuum test up to the end vacuum limit of your pump, at the beginning of distillation in spinning band?

But how else can I make sure my vacuum is ok or in other words that my Pump reach the Limit and that there are no leaks?

Thank you very much for response.

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I’d fill the cold trap before pulling a dry vac, but starting with a test is a good way to see if you have any major leaks.

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Also with the flask filled with crude, any dissolved gases could definitely lead to an higher reading than with nothing in the flask.

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Yes i know that, but before i put my vacuum on the system, all my cold traps are filled with liquid nitrogen (-196°C). So if there would something gasing out, it should be in the cold traps, not in the pumps? I have one cold trap which is -30°C and after this cold trap i have a double cold trap, which is filled with liquid nitrogen.

Ore are there some gases, which also passes the liquid nitrogen cold traps?

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There might be, but we should bring in someone smarter than me.

@MagisterChemist
@RockSteady

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you should set yourself up a vacuum manifold. Place kf tee on the top of your pump with a valve on one side and a thermocouple vac gauge on the other. From the valve connect to your cold trap with a bellows. Word of caution here, bellows will shrink in length under vac, make sure there is plenty of slack when setting up.

When your ready to use your apparatus you can start up the isolated pump and set up for your distillation/ fill cold traps while the pump is being checked for ultimate vacuum level.

When your ready to go just open the isolation valve, and go.

pump

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