Sciencemadness Discussion Board - Preventing flowback without inverse funnel trap or extra container?

Preventing flowback without inverse funnel trap or extra container?

Draeger - 5-7-2020 at 12:44

I thought that maybe I'd buy two flasks, a hose adapter and a gas insertion tube. I'm worried about flowback, but I would like to avoid buying another flask.

Is there any other way to prevent flowback?

Syn the Sizer - 5-7-2020 at 13:12

I like to have a middle bottle. I do realize it means you need 1 more flask but even with an inverted funnel you can still get suck back even if it's not very common. It happened to Tom on his Extractions and Ire channel ruining his nitric acid. A middle bottle catches the accidental suck back before it ruins your product. I use a 2 neck flask with 2 single hole rubber stoppers and glass tubes. I understand for some applications rubber is not good, such as dealing with HNO₃ vapours but it works in a pinch.

That is my best suggestion to prevent suck back into your product, short of watching like a hawk and catching it before it happens. I realize you are looking for another fix.

[Edited on 5-7-2020 by Syn the Sizer]

Draeger - 5-7-2020 at 13:32

Quote: Originally posted by Syn the Sizer

I like to have a middle bottle. I do realize it means you need 1 more flask but even with an inverted funnel you can still get suck back even if it's not very common. It happened to Tom on his Extractions and Ire channel ruining his nitric acid. A middle bottle catches the accidental suck back before it ruins your product. I use a 2 neck flask with 2 single hole rubber stoppers and glass tubes. I understand for some applications rubber is not good, such as dealing with HNO₃ vapours but it works in a pinch.

That is my best suggestion to prevent suck back into your product, short of watching like a hawk and catching it before it happens. I realize you are looking for another fix.

[Edited on 5-7-2020 by Syn the Sizer]

Ah. Well, it's rather since I can't find flasks for under 10€ so 3 flasks are more than 30€, and that would just be the flasks, so that would be quite expensive, and I really don't like ordering from China since I'm impatient.

outer_limits - 5-7-2020 at 15:49

You can use filtration flask if you own one, depending of course on it's volume and predicted volume of possible flowback.

SWIM - 5-7-2020 at 19:01

These polypropylene check valves are cheap.
https://www.ebay.com/itm/3-8-8MM-Plastic-One-Way-Inline-Chec...

One in the line to prevent flow-back, or one as a vent to prevent the vacuum which causes flow-back?

Refinery - 6-7-2020 at 09:40

PP check valves are a good option.

If you're in a hurry, basically any bottle or flask can serve if you get some sort of closure to it. Even as rudimentary as PE packing foil can do. I have a couple of rubber and silicon plugs which I have drilled two holes in. They are a bit tricky to drill, but it works. The drill partially cuts and partially grinds the rubber/silicon away.

Compatibility is not such an issue if the parts are small and the exposure is only temporary, like few hours at max. The guy that made ketene lamp in youtube used rubber plugs and although it is totally not compatible, it works for the small time. For materials especially suitable for storage it is very important because exposure is infinite.

Boffis - 6-7-2020 at 12:09

Whats wrong with the good old inverted funnel? I use this method all the time with both chlorine and ammonia. I recently inlustrated the use of a gooch adapter type funnel (ex Ebay) for the preparation of alcoholic ammonia.

Draeger - 6-7-2020 at 13:42

Quote: Originally posted by Boffis

Whats wrong with the good old inverted funnel? I use this method all the time with both chlorine and ammonia. I recently inlustrated the use of a gooch adapter type funnel (ex Ebay) for the preparation of alcoholic ammonia.

It wouldn't have worked in my case since I needed a closed system to prevent anything toxic to be released since my area isn't ventilated.

I'm not going to be able to buy from the supplier I originally wanted to buy from anyway, though, so I'm just going to try and buy 3 flasks.

Thanks everyone for the replies.

draculic acid69 - 6-7-2020 at 20:36

Quote: Originally posted by Refinery

PP check valves are a good option.

If you're in a hurry, basically any bottle or flask can serve if you get some sort of closure to it. Even as rudimentary as PE packing foil can do. I have a couple of rubber and silicon plugs which I have drilled two holes in. They are a bit tricky to drill, but it works. The drill partially cuts and partially grinds the rubber/silicon away.

Compatibility is not such an issue if the parts are small and the exposure is only temporary, like few hours at max. The guy that made ketene lamp in youtube used rubber plugs and although it is totally not compatible, it works for the small time. For materials especially suitable for storage it is very important because exposure is infinite.

I tried drilling rubber bungs and I've heard that it's best to freeze them first.

Eddie Current - 6-7-2020 at 21:04

Quote: Originally posted by Draeger

I thought that maybe I'd buy two flasks, a hose adapter and a gas insertion tube. I'm worried about flowback, but I would like to avoid buying another flask.

Is there any other way to prevent flowback?

I recommend these multi size two hole silicon stoppers if you can find them. They cost me around $7-8 each and can be utilised with teflon tubing and suitable bottles as gas scrubbers for the hobbyist.