Syringe filters and air bubbles

Does anyone have any tips for syringe filters?
I’ve got the feed line for my roto rigged up so I can run two stacks of 1μ->.45μ->.22μ filters inline just for my own peace of mind after media filtration. Trying to inline that with a triclamp filter setup so I can go straight from polishing filtration to recovery. Flow rates are about what I’m looking for, but occasionally there are bubbles in the feed line and my syringe filters get airlocked. Any tips for preventing airlock? Or does anyone have a good device that will remove or eject those bubbles from the feed line?

I’d go with something larger than a syringe filter.

I’ve purchased 0.45um and 0.2um filter disks in 3" or 4" diameters before in both nylon and nitrocellulose.

maybe 2" would work for you?


would one of these work for your purposes? It’s not inline, so it’d really only be useful in smaller quantities unless you modify it somehow

good call. I’ll look that direction. shied away initially because of the cost of the filter holder, but now that I’ve got most of it worked out I’m gonna go ahead and make the jump. appreciate the response

I found that the nitrocellulose ones needed to be prewet with ethanol before trying to secure them, and not allowed to dry until you were done, otherwise they tended to shatter.

I just captured them along with a gasket in a triclamp connection. used a 20mesh screen gasket as a backer. the stretch on that gasket may have been why I had breakage issues, but wetting solved those, so I didn’t go any further.

not tried the nylon ones.

they won’t catch fire like nitrocellulose (flash paper!)


Okay, I’m remembering the other reason I was avoiding the nylon filters. occasionally I’ll see trace acetic acid in my ethanol after its been recycled a dozen or so times. I’m guessing its a very very small amount, but I’m still cautious about that really poor compatibility rating. Looks like there are PTFE filter discs out there so I may try to go that route.

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search for inline hplc filter in google , waters have these kind of filters ,usually its stainless steel .

yeah, most of the SCF units I’ve seen are using Swagelok filters, usually inline rather than tees, but they’re expensive (relative to 1000 syringe filters) only offer elements down to .5µm, have relatively smaller filter surfaces, get cleaned by backflow flush. Syringe filters are nice cause you can toss them when they clog, will handle 75psi inlet, are easy to find down to .2µm.

I finally just gave up on right sizing my sub micron filtration to the application and got a couple stainless housings & cartridges from United filtration, I figure with how little particulate gets though the 10µm and the filter papers I’ll be dead before they actually need to get cleaned.