<![CDATA[Do you actually need a vent needle when filtering into a 5mL sterile vial?]]>Been going back and forth on this for weeks and want to hear from people who actually filter.

My setup: reconstitute in the original vial (0.5-2mL bac water depending on the peptide), draw the full contents into a 3mL Luer Lock syringe, attach a 13mm PES 0.22um filter, attach a fresh 21G on the output side, push through into a sealed 5mL sterile receiving vial (ALK).

My biggest transfer is about 2.15mL into a 5mL vial. That is less than half the vial's air space.

I keep seeing people say you need a vent needle in the receiving vial to let displaced air escape while you push liquid in. Some people use a plain 18G, some say you need a filtered 0.2um hydrophobic vent, and those things are either impossible to source as an individual or cost $300+ each.

But if I am only pushing ~2mL into a 5mL vial, is the back-pressure actually a problem? It seems like the air just compresses a bit and the syringe plunger handles it fine. Has anyone here actually tried filtering into a sealed 5mL vial without any vent at all?

If you do use a vent, are you using a plain open needle or a filtered one? And if plain, does that not defeat the entire purpose of filtering since you just gave room air a direct path into the vial you are trying to keep clean?
Genuinely trying to figure out the right move here.

Appreciate any real experience.

]]>https://community.peptidecritic.com/topic/1092/do-you-actually-need-a-vent-needle-when-filtering-into-a-5ml-sterile-vialRSS for NodeThu, 23 Apr 2026 11:49:57 GMTWed, 15 Apr 2026 08:31:47 GMT60<![CDATA[Reply to Do you actually need a vent needle when filtering into a 5mL sterile vial? on Thu, 16 Apr 2026 14:40:53 GMT]]>@STATIEEIGHT said in Do you actually need a vent needle when filtering into a 5mL sterile vial?:

@ResearchCat
Ahhh - can in fact confirm that attempting to fill a pen cartridge with 2.5ml of BAC & 30mg of RETA without a vent needle will in fact eject the plug like a pop gun and spray the liquid all over one’s own fat guts.😂

Lol. I sacrificed a cartridge for my first time filling one using tap water so I can practice. Good thing I did. Totally forgot the vent needle and sure enough it popped out.

]]>https://community.peptidecritic.com/post/4054https://community.peptidecritic.com/post/4054Thu, 16 Apr 2026 14:40:53 GMT<![CDATA[Reply to Do you actually need a vent needle when filtering into a 5mL sterile vial? on Thu, 16 Apr 2026 14:08:08 GMT]]>@statieeight 🤣 laughing with you, not at you. I haven’t had that happen, but I have blown over the vent and spilled SS-31 all over my hands and desk.

I did not expect reconstituted peptides to be so, well, sticky. what a mess!

]]>https://community.peptidecritic.com/post/4049https://community.peptidecritic.com/post/4049Thu, 16 Apr 2026 14:08:08 GMT<![CDATA[Reply to Do you actually need a vent needle when filtering into a 5mL sterile vial? on Thu, 16 Apr 2026 06:15:38 GMT]]>@ResearchCat
Ahhh - can in fact confirm that attempting to fill a pen cartridge with 2.5ml of BAC & 30mg of RETA without a vent needle will in fact eject the plug like a pop gun and spray the liquid all over one’s own fat guts.😂

]]>https://community.peptidecritic.com/post/4024https://community.peptidecritic.com/post/4024Thu, 16 Apr 2026 06:15:38 GMT<![CDATA[Reply to Do you actually need a vent needle when filtering into a 5mL sterile vial? on Wed, 15 Apr 2026 14:18:31 GMT]]>@myb this! The primary context I see vent needles being used is for loading pen cartridges, where they are pressure neutral and filling the Cartridge without a vent may (will?) push the plug out. When I am moving peps from one vial to another, I do not vent.

]]>https://community.peptidecritic.com/post/3957https://community.peptidecritic.com/post/3957Wed, 15 Apr 2026 14:18:31 GMT<![CDATA[Reply to Do you actually need a vent needle when filtering into a 5mL sterile vial? on Wed, 15 Apr 2026 13:23:04 GMT]]>My experience. Your empty vial should be under vacuum, from being sterilized, and will pull your liquid in. If you hit a stopping point pull back on syringe and finish your push. Repeat pull and push as needed.
I only vent on pen vials. Adding a filter to your vent is a personal choice, some do some don’t. You filter the peptide because sterility is often unknown.

]]>https://community.peptidecritic.com/post/3955https://community.peptidecritic.com/post/3955Wed, 15 Apr 2026 13:23:04 GMT