[Fatturtle]

How long is is suppose to purge at those parameters; 29.5 hg and 90-95 f?
Anyone purging at a lower hg?

I am trying to get shatter with a smooth uniform
appearence. Having problem with a bunch of small
bubbles forming inside the shatter.

I am using -40 butane and dryed frozen material
or dewaxing in a seperate vessel so I have very little
wax in my product

[WaterFarmFan]

I don't purge butane (only ethanol which has a higher boiling point), but if you have small bubbles that form inside and don't escape, than it means your temps are too low and you have not fully purged solvent. I don't think there is ever an exact time period, because the thinner the film, the faster the purge. You just have to watch the slab. I personally start at lower temps and when the bubbles stop breaking, bump up the oven 5F until you hit your peak (120-125F for ethanol). You can also flip the slab or stir a bit to expose material underneath, but a thin film is always better. With a proper thin film, you will know when to stop because your slab is smooth like glass with some cheese holes but no bubbles anywhere. Deeper vacuum levels means lower temps for same purge. If you are using a vacuum chamber with heating element, then you need to pay close attention to heat the walls of the chamber and not just the bottom, as the bottom of the slab will be hotter than the top if not thin filmed and bubbles can become trapped this way.

[Gray Wolf]

Originally Posted by Fatturtle

How long is is suppose to purge at those parameters; 29.5 hg and 90-95 f?
Anyone purging at a lower hg?

I am trying to get shatter with a smooth uniform
appearence. Having problem with a bunch of small
bubbles forming inside the shatter.

I am using -40 butane and dryed frozen material
or dewaxing in a seperate vessel so I have very little
wax in my product

Preheat your oven to 100F or so and add the concentrate in a thin film.

Raise the temperature in 5 degree increments, until the material just fully melts, typically 110F to 115F.

Once fully melted so that the surface tension is low enough for the bubbles can escape, pull your vacuum.

Here is a link to the way I do it: https://thealchemistresource.thealchem istresource.com/p/normal-0-false-false-false_27.html

[~star~crash~]

At my elevation the best vac (in a chamber) i could achieve was hovering around 28 hg and i still got good results ...multiple pulls and remelting helped a ton ...peace

[SkyHighLer]

Originally Posted by ~star~crash~

At my elevation the best vac (in a chamber) i could achieve was hovering around 28 hg and i still got good results ...multiple pulls and remelting helped a ton ...peace

Elevation has nothing to do with the vacuum you achieve inside your chamber.

Your (Bourdon tube) dial gauge references ambient air pressure, it is off by about one inch of mercury per thousand feet above sea level.

"Bourdon tubes measure gauge pressure, relative to ambient atmospheric pressure,"
https://en.wikipedia.org/wiki/Pressu...rement#Bourdon

If you're at ~2,000' above sea level, and your dial gauge reads 28.0" Hg, the vacuum inside the chamber is actually ~29.9" Hg.

[~star~crash~]

https://anver.com/vacuum-lifters/atmospheric-pressure/

[SkyHighLer]

Originally Posted by ~star~crash~

https://anver.com/vacuum-lifters/atmospheric-pressure/

From the page you linked to,

"It is important to consider the relationship between atmospheric pressure and altitude as it affects vacuum pump performance. Basically, the higher you are, the less vacuum you can attain.

Because free air is less dense at higher altitudes (i.e. lower atmospheric pressure) operation at these higher altitudes has the effect of reducing the capacity and maximum vacuum levels attainable. In general, flow is not affected, only the maximum vacuum level attainable.

The basic formula is:

Current Atmospheric Pressure x Max. Rated Level of a Vacuum Pump
29.92″ Hg (absolute vacuum)

Refer to the following table to correct for vacuum pump performance at various altitudes."


Complete BS!!!


I have addressed this previously here,

https://www.icmag.com/ic/showpost.ph...17&postcount=5

[~star~crash~]

ok ... i believe you! peace

[SkyHighLer]

I've been replying to the same question for years. Here's the best explanation I've seen.


Ask Cascade – Vacuum Gauges at Altitude

On April 23, 2015

Why Does The Gauge on My Oven Read Differently in Denver Than Seattle or Portland?

The analog gauge in this oven is a relative vacuum gauge that uses ambient atmospheric pressure as a reference point for comparison to the pressure (or lack thereof) inside.

Atmospheric pressure is the pressure exerted by the weight of the gasses and other particulates in the atmosphere (air) surrounding the Earth, which are held in place by gravity. At sea level, the weight of a 1 cm x 1 cm column of air rising to the top of the atmosphere (about 62 miles) is 1.03 kilograms. The majority of the air in that column (75%) exists within the first 6.8 miles above sea level.

The higher you go above sea level, the less atmosphere exists in the 1 cm x 1 cm column of air between you and the end of the atmosphere. Less atmosphere means less weight, which means less ambient pressure – and within the first 6.8 miles, even a few thousand feet can make a pretty big difference.

Because Denver actually does sit a mile higher than sea level, there’s significantly less atmospheric pressure there than Portland or Seattle. This means the difference between the pressure inside an oven while under vacuum (which gets pretty close to containing zero atmospheric pressure) and the ambient pressure there is not as great as it would be at sea level. And because a relative vacuum gauge is actually measuring the difference between the pressure inside the oven and outside the oven to calculate the level of vacuum, it will give a lower reading.

As a rule of thumb, a relative vacuum gauge will read 1” Hg lower for every 1,000 feet of elevation. So at sea level, the gauge of a TVO-2B or TVO-5B connected to a Welch 2052 or 2042 pump would give an average gauge reading of 29.85 inches Hg. That same setup will give an average reading of 24.85 inches Hg in Denver. It is important to note, however, that the actual level of vacuum inside the oven is identical whether you are at sea level or not.

While you could calibrate your relative vacuum gauge for altitude, the reality is that it’s more trouble than it’s worth. Should your application require a precise pressure reading your best bet is to add a digital pressure gauge.

https://cascadebotanical.com/blog/va...auge_altitude/

[Fatturtle]

I am at 1500 ft altitude and was tired of guessing at
what pressure my oven was at so I got a yellow jacket 69075 vacuum gauge and can testify that you
can reach full vacuum at altitude inside your oven.

Hey GreyWolf, for how long would I have to purge
at your parameters (29.5 hg and 115 f) to get
down to 100 ppm residual?