Dual cold trap configuration for SPD

I’ve been thinking about getting LS dual inline cold trap for a while now (company has some purchase credits with them so it would almost be no cost), but looking at it I’m confused about the design. It would make sense to me that two cold traps should be staggered, like this:

This way, the incoming vapor from trap 1 to trap 2 has to travel up condenser 2, in theory giving it more time exposed to the cold glass and more time to condense. I think I’ve seen a lot of pics on here where people have their traps staggered vertically like this.

Lab society has a different arrangement as seen below:

Here it seems like the incoming vapor from trap 1 to trap 2 is not forced to have as much contact time with the cold glass before exiting thru towards the pump. Wouldn’t this be less effective?

Also, what is going on here:

It looks like another wall? Does this force the vapor to go down before it can travel up? Kinda confused and can’t quite make sense of what that is from the picture.

Is there any reason why I should get this LS set up instead of 2 24/40 cold traps from Rocco? I’ll be using dry ice slurry. I could see that maybe the LS one could be better if the second trap accommodates an immersion chilling coil.

Also, on the LS set up, they have a place to monitor vacuum. If one only has 1 digital vacuum monitor, would that be the best place to plug it in, in between the cold traps?

Dont waste your time with glass. Just hit up @Killa12345 and get SS cold traps. :100:


I agree with @BG305
Get 2 ss cold traps


Seems he is sold out. Benefits of SS - harder to break obviously. And better cooling properties? Probably would work better/safer with LN2 also? Didn’t know these were a thing in this configuration. I like it, thank you!


Send him a DM about them.


Will do! And regarding the configuration, am I correct in thinking that vertically staggering them (so that the top port on the first one connects to the bottom port on the second) is the way to do it? Or does it not really matter that much?

Yes. Thats correct.

The way they have it is best for their design based on the design of the second cold trap.

If u had two normally designed cold traps, then yes staggering them like ur first drawing is best.

For best monitoring, the vac gauge should be in the system past the condensers and before the first cold trap.
For low mainentance monitoring, after ur cold traps and before your pump is best.
Cheap gauges should be used in the system and expensive ones should be protected by placing them after all ur cold traps and always vertically facing down.

SS cold traps tend to be much larger and have a better thermal transfer between the slurry and ur vapors.
Ln2 can be used in both but safer in SS.
Dry ice/immersiom chiller can be used in both and safe in both.
Imo u only need one ss cold trap unless ur running a diffusion pump or hot condensing at 1l/hr+ then id get multiple


@Killa12345, can you post a pic of these ss cold traps?

they will be back in stock in around 2 weeks. NONE of the factories im purchasing are at near 100% working capacity. Most are still 50% or more shut down…most of my sales people are working from home still with very little access to production lines and able to give me updates on a lot of my orders… Im literally just getting shipments from chinese new year now.

Its been a bit rough sourcing from china lately with the parts that do ship…The US customs just lets them boxes sit in quarantine for 2 weeks before even touching them…There are ways around this slow production and shipping but the cost is nearly 3x and im not willing to pay that as of yet for shipping and priority express shipping from china which is usually here in less than 48 hours.



These traps cause blow through. They aren’t that effective.

Monitor vacuum either at pumps or at th spd. Not at the traps. The cold vapors will condense and trick you gauge at times.

These traps have a extra wall in one section, Wich doesn’t do anything but heat up your di slurry. These are high inneficient traps.


You can’t use ln2 unless you pre trap everything before it. Also basic as cold traps don’t trap better than glass…glass is super effective.

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You are wrong. Sorry bro.

The design is flawed and always stack traps. The reason is you want gravity to hold molecules down as dry vacuum clear the trap to the pumps. It doesn’t matter what trap used, always stagger for beat results.

If you watch carefully the top of the ls trap warms up from vapor coming in. Typical traps should allow warm vapor to enter at bottom and remain chilly at top. It doesn’t occur with this setup and warm vapor path.


Where’s the “notify me when back in stock” button? Might be a good idea in the world of jacked up supply chains.


let me see if i can add that to the website…im sure their is a plug in…thanks for the suggestion…that is a good one. when they are back in stock…ill give you 5% off for that suggestion…that is the top of the list for options i need to add this week! thank you so much!


I found myself saying “pretty cool, too bad I’ll forget about it by the time he gets them back in stock”. You are more than welcome good sir. Level it up!!!


i got some sorta notify me option up there now. its kinda janky till i find a better one. Its a start… :man_shrugging:


U got cold traps now @Killa12345? I’ll take 4 killa traps plz


That thing is gorgeous!


Nah, i think your wrong and just trying to misguide people on a sale. i think u need to look at the design closer. These are a superior design if used for ur 2nd or 3rd cold trap but not as ur first one.