Been trying to upgrade my setup taking me over 24 hours to run a 5 liter

Just wanting to know what head to switch to and what I can do to speed up my processes
I have a welch duoseal 1400
5l chemglass boiling flask
Ai head know that’s one of the problems and looking for the best head to switch to
Also wanting to know what to do to upgrade coldtrap
Really wanting to stop using dry ice

@david has good stuff

The head is not your main issue
The vacuum pump is the Welch is rated at 0.9 cfm for a 5 liter flask
Where several of us recomend a 4cfm the liter so in your case a 20 cfm pump
A wide bore setup from @david should help as well

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Is that the math that’s considered standard? 4 CFM per liter?

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There is no math to it :thinking:
But @anon42519203
The lady that provides his vacuum gear and the lady of beaker and wrench
Myself are convinced that a high CFM is better along the way the 4 CFM came out as the minimum rating per liter flask and 8 CfM the upper limit per liter flask

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So what would be a good pump to upgrade to I can just use the welch on my 2l instead and then upgrade to a better pump on my 5l

At the very least a alcatel 2021i. The trivac leybold 2.5d is only slightly better than the welch 1400. I own all 3 of the above.

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Math being just like slang for is that the average rate we’ve come to

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The Edwards 30 serves me well on a 5 liter has a good cfm even at deep vacuum (@spdking gave a very wel written explanation)
The leybold are also very good pumps
Alcatel adixen has good pumps
I have a 8 cfm Alcatel 2008a on a 2 liter rig keeps me below 100 mic in mains
Yust not a hvac brand or Chinese pump I would recomend

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I recomend 6cfm de literal average
4 bare minimum
8 best
Cfm higher than 8 a liter has gotten me and @anon42519203 muffin issseus
But he @Beaker (rip) ran A Edwards 30 on 15 ml crude oil in his cold finger rig
And several friends of mine run the Edwards 30 on 2 liter rigs without isseus ( mains at 6 micron )

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72 cfm 100 micron ultimate vac depth seems to be the maximum for a 22L system without having to throttle it. For mains, anything past 600L/s of diff power seems to get the ultimate vac as low as 10 micron in the system during mains.

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So deepest vac without diffusion pump on a 20 liter rig was 100 mic
With a diffusion pump able to pull mains at 10 mic
I run a 10 liter with wide bore and a leybold trivac 65 mains in the 30. / 50 mic region and with diffusion difstak 700 ISO in the 5 /15 mic region
Guess I have to upgrade in vac grease :grin:

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Stainless cold trap so tou have the options to fo full bore if and when tou want. But get and alcatel 2021i you can find them for arund500 + on ebay and it will change everything

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So I’m getting a client a 20L SPD what pump can get 80 CFM ? That seems absurdly strong. The CRV 30 is only 22 CFM

Wouldnt a turbo molecular pump work best on large spd setups?

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I run a 12 liter with a leybold trivac 65 B
Any one running a 20 liter I would recomend that as minimum with diffusion as the best
Big sized kf40 baffles and if possible
Ns 32/40 coldtrap connects but I am in Europe where 32 ns is more common

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Ya except the mechanical coldtrap is only KF15 unfortunately

Pfff that better be a bigass mechanical coldtrap
What type of head is the intention
And instead of glass coldtrap if necessary go with a stainless steel one
Way easier

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What temp is your head at while running? I got 24 hour runs when going low and slow with vapor temp at 165. Im doing 185 vapor temp now and getting 1l in 4-5 hours with dual 2021i. So, in my opinion it’s more down to temps than vac. With my pro8 and chasing temps, using ls silvered head with structured column getting the boiling flask up to 240c in the end I got 500g per hour. Color obviously goes darker, but it depends on what separation you want. And that’s not with wide bore. My wide bore cold trap just broke forcing me to go back to the gl trap and the run, using the same parameters and wide bore took 4 hours per liter compared to 5 hours with the wide bore. Just saying.

Speaking of grease, I’m about to stop using that all together. Im going for ptfe sleeves. Super easy to set up and break down and pretty much very little difference in vac levels.

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