Sciencemadness Discussion Board

Anyone interested in 5mm diameter chemical-resistant one-way tubing valves?

Melgar - 23-10-2016 at 09:57

Normally these things are about a buck each, but assuming I don't mind waiting a month, I can get 100 for $46:

https://www.aliexpress.com/item/3-16-5mmViton-one-way-valve-...

Now, I obviously don't need that many, but these things are really useful for preventing suck-back when gassing a liquid, and are a lot easier to put inline than the usual apparatuses. Also useful for preventing diffusion into a disconnected tube (ie, a drying tube), since it takes a slight pressure differential to open it. I stopped having as many accidents since I started using these things whenever I'm generating a gas and sending it somewhere via tubing, since it's kind of a pain in the ass to set up a jar-type suck-back trap, and even when they work, they're a nuisance.

Anyway, would anyone be interested in getting some here? I'd probably price them at $5 for the first five (to cover shipping), then 50 cents each after that, to anywhere in the US. Or 50 cents each with no shipping if you happen to be coming through New York City. I'd put in the order as soon as I get up-front payment for at least half of them, if there's interest.

Edit: I generally only have to wait 1-2 weeks for shipments from China, since I'm about a 30-minute subway ride from the main customs clearing center for the East Coast. So I take that back; you probably wouldn't have to wait as long as the listing implies.

Edit 2: Apparently 7mm valves are the same price, which is pretty close to 1/4 inch, and should work just fine with quarter-inch tubing:

https://www.aliexpress.com/item/7mmViton-one-way-valve-non-r...

Of course, that one is polypropylene, and says it's meant for use with water, even though the title says Viton. Still should be good for most purposes, although I notice they they sneakily said "gasoline engine" rather than "gasoline". For that price, you can afford to have them fail occasionally though.

Edit 3: Apparently their valves from 3mm to 12mm are all the same price. I mostly use quarter-inch tubing though, so I'd probably actually go for the 6mm ones, based on the dimensions they show for the different sizes.

[Edited on 10/23/16 by Melgar]