What gauge breather needle to purchase?

[A Former User]

Hi all, new to filtering peps and pens, just ordered 3 V4s from the shop! I watched Randy’s vids, and I have the following supplies down:

3ml sterile pen cartridge vials
3ml 23G 1 inch luer lock syringes with needles
0.2um 13mm PES filters
30G 0.5 inch luer lock needles

My question is, what gauge should the breather needle be? If there’s anything in my supplies list that stands out, or I’m missing, please let me know. Thanks all!!

[WisGal64]

I've been using a 30G 1/2" for venting/breathing, what have on your list should work fine. I had initially tried a shorter needle but that didn't go so well but it was when I first started and was nervous about getting everything right

[vpeptides]

I don' use a breather needle. I inject the liquid through the filter, then detach the filter from the needle to let the extra air out.

[Snake Pepskin]

I use an actual pen tip needle, and when I’m done filling the cartridge, I use the same needle for the first dose. No waste

[ResearchCat]

I use 30/31g

[ResearchCat]

@vpeptides The problem with that is blowing the plug out of the cartridge. Are you filling carts without a vent and not having the plug come out? That seems unlikely to me.

[vpeptides]

@ResearchCat I was talking about a 3ml vial, not a cartridge. Didn't read the post carefully. I am a writer, not a reader, you know?

[Eleanor]

This post is deleted!

[Eleanor]

@vpeptides How do you tell when all the air is out of the vial?

[ResearchCat]

@vpeptides All good! Thanks for clarifying. That makes sense.

[vpeptides]

@Eleanor it happens momentarily

[Eleanor]

@vpeptides Ok, does it hiss, pop, any indication?

[vpeptides]

@Eleanor Long story: It hisses when I slightly release the needle from the filter to equalize the pressure. Then I reconnect it and disconnect the filter from the syringe to add more air into it, then reconnect again and push to let whatever is still in filter to go through. Then disconnect again the needle.

[A Former User]

Thanks all! So excited to get started with filtering and pens!

[sgirmant]

For those using a 3 mL syringe, what size and length breather needles do you recommend? Also, what size and length reconstitution needles work best?