BVV Sight Glasses Cracked

First run on my BVV Mk-5 today and the sight glasses completely cracked. Thinking it’s due to cold temps - had some acetone boil over from the dewaxing column when adding solvent which wasn’t cold enough and it splashed the sight glass. Not sure if that’s to be expected - I wouldn’t imagine so seeing as the collection vessel is submerged in a dry ice slurry but perhaps I’m wrong?

Lucky I caught it or…

Here’s a pic, tell me what you think.

Edit Upon further examination it appears the lowest effective working temp for polycarbonate is -40*C. That doesn’t seem safe to ship units with.

Is the sightglass 100% polycarb?


Yeah the sightglass is 100% polycarb by their description. I’d link you it but I can’t share links yet. I’m looking at the borosilicate sights are a replacement but just wanted to come by here to get an opinion.

I feel pretty strongly in system marketed as passive that all components should be safe for use with dry ice temperatures. I guess I kind of just want to see if that’s a valid feeling or not.

did that clamp come tightened by BVV or did you tighten when you got??? what torque did you take them to if you tightened?

im not personally a fan of these clamped in sightglasses.


Yeah over tighten possibly


Came loose when I got it so I re-tightened it. Didn’t measure the torque but didn’t go crazy on it.

Why are you not a fan, just out of curiosity? I like being able to look down to see what consistency my oil is at, but of course using a refrigerant scale can give me some level of accuracy there.

I think it’s just the clamp style he not gonna like…

Really easy to put a lot torque on it…crack!


Perhaps you’re right but both of them failed and there was no cracks prior to the spill.

Ah well, the borosilicate will be an upgrade either way… albeit one I didn’t want to pay for.


Learned some chemistry today in examining this failure. Acetone and polycarbonate are enemies. Acetone will significantly weaken the structural integrity of polycarbonate, so when it hit the poly it immediately caused it to lose its integrity. I’m trying to determine whether or not the slurry is worth all the mess and hassle - could anyone share their thoughts on the matter? Sucks because I just bought $160 worth of acetone, but it causes over half the dry ice to boil off when I add it to the slurry for the spool, and this spewing problem from the dewaxing column sucked balls.


Try denatured alcohol


I second denatured alcohol. The temp difference is like is only like -6c difference.


I would still have the same problem with rapid boiling when adding a warmer solvent though, wouldn’t I?

What’s our sight glass made of?

Almost positive it’s borosilicate. It’s the most expensive option they sell, and the price difference between the two and even the metaglass is so negligible. I don’t want to get into the details of it but from the cheapest option to metaglass is like $15. I don’t understand why companies would cheap out on this. I’ve used acetone for years without cracking a sightglass and never to this day have heard someone cracking one.

I will say this is the 3rd or so sightglass cracked like that. All of which are clamped on like the OP

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Are you saying you don’t recommend borosilicate? Price different between the boro and the metaglass is huge…

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The price difference isn’t huge when ordering this stuff from China. And personally I don’t know what glass I have. I just asked for the most expensive/thickest option they had.

I know a bit about the true cost of these things. While BVV might charge a extreme markup for metaglass. The real cost is very negligible when sourcing from China


But how do you know you’re getting real metaglass from China?

I have no doubt BVV up-charges up the ass.

Was just wondering… Thanks bro

Op…I use acetone for few weeks and denatured alcohol ever since…it gets on it plenty…no issues yet…

But mine don’t clamp like that

I had those on my collection pot and dewax column from bvv they all cracked, I upgraded to the borosilicate ones and haven’t had any issues since, they have a metal ring that contacts the clamp so that they dont crack, and they dont scratch up either…

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Ugh. Maybe I will make the switch. Just sucks to have learned this the hard way. Know any uses for 8 gallons of acetone? I guess giving my girlfriend enough nail polish remover for the rest of her life :joy:.

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