VM Still extremely slow

Reflux still design and discussion

VM Still extremely slow

Postby petermet » Sat Jul 31, 2021 7:56 pm

I have a VM still (copper)
It is packed with stainless steel scrubbers up to 1300cm.
The column is 2 inches
The boiler is charged with 25 litres @ 40%
The element is voltage controlled but is 2kw flat out

I am getting 96% flat out with a rate of 200 mls an hour !!!!
There is no flooding and the needle valve is fully open
Cooling water is at 55-60 degrees but i'm in Indonesia and tap water is 30 degrees to start.

Is it just a case of overpacking?
Posts: 4
Joined: Sun Feb 14, 2021 8:47 pm
equipment: 1 3/4 " VM still
Pot still (converted SS reflux)

Re: VM Still extremely slow

Postby BigRig » Sun Aug 01, 2021 9:25 am

Assuming it is 1300mm not 1300cm. Sounds like it might be too tightly packed
Posts: 299
Joined: Sun Apr 07, 2019 1:29 pm
Location: Brisbane, QLD
equipment: FSD 4" Mac SSG, 50L Milk Can, 2 x 2400w elements, 35L Digiboil Boiler

Re: VM Still extremely slow

Postby howard » Sun Aug 01, 2021 12:55 pm

assuming the scrubs are something like the picture.
i have a 2", 1100mm packed column and 1500-1700w should be plenty for a 25L.
my packing is SS scrubs & copper mesh combo.
but if i work out my scrubs (11 scrubs in 700mm), you should have around 17 scrubs in 1300mm?
scrubs can be different sizes i suppose, so mine are 40gms each.
the weight of scrubs for 1300mm should be around (17 x 40gms) around 700gms?
i ram my scrubbies in fairly hard, but i can still breath easily through the column.
not sure if my maths or weight ratio idea is ok, it's sunday morning :))
You do not have the required permissions to view the files attached to this post.
Posts: 175
Joined: Fri Jul 17, 2020 12:53 am
Location: perth
equipment: 35l brewzilla
2" modular CM
gin caddy
changeover element switch and voltage controller on brewzillas 1900w element.
5L glass boiler/glass leibig

Re: VM Still extremely slow

Postby petermet » Sun Aug 01, 2021 5:53 pm

Thanks Both,

I will persevere finishing this run the check the weight of the scrubber once clean and dry.

Howard can I ask what take off speed you achieve and at what purity?
Posts: 4
Joined: Sun Feb 14, 2021 8:47 pm
equipment: 1 3/4 " VM still
Pot still (converted SS reflux)

Re: VM Still extremely slow

Postby warramungas » Sun Aug 01, 2021 7:10 pm

Not too much passive cooling of the column preventing vapor reaching the top?
If it qas too tightly packed Id expect your strength to be lower or youd be pressurising your boiler.
Posts: 1434
Joined: Sun Oct 18, 2015 9:38 pm
Location: Nor Perth
equipment: 180 litre fermenter x 2
30 liter boiler
2" four plate modular bubbler
2" one meter long LM column
110 liter boiler with 25 liter (max) inline thumper
4" x 4 plate bubble cap still

Return to Reflux Stills

Who is online

Users browsing this forum: No registered users and 5 guests