Adjusting for liquid in syringe needle and tip

[favor1]

I think this is what has been screwing up some of my samples. I like to mix my test batches at volumes of 1ml and I've been running into an issue when using very small amounts of liquid due to excess liquid in the needle and tip (my assumption, using tuberculin syringes). When I'm mixing 1ml batches and want to add, say 1% of this concentrate and 1% of another, I end with values like .02 or .01 ml for the concentrates, which is tuberculin syringes can still measure, but when you look at the needle tip, it looks like it can hold an extra .01-.02ml on its own. Do you guys adjust for this by reading all of these measurements minus .01 or .02 ml? For example, drawing liquid flat to the 0ml would be read as .01ml or .02ml? Thanks a lot.

 

[Fiamma]

I draw juice to where it shows what I want then I pull the tip up out of the liquid and suck air up to see how much there really is and adjust from there.

 

[favor1]

Hmm, that sounds like a good tactic. I just measured the volume of the tip + needle of my syringe and it turns out to be .05ml, which means when I was mixing .01ml aiming for 1%, I was getting about 5%, what a stupid mistake

 

[Cyrus Vap]

you can also change needles before you inject

 

[wizard10000]

My 2" 16 gauge needle holds about 0.1ml. Perhaps making larger test batches is the solution?

When measuring flavoring what I do is pull some air into the syringe, watch what's going on and stop pushing the plunger when the syringe barrel is empty - then I blow that last couple of drops back into the flavoring bottle.

If you're worried about waste what I do once I get the test batch where I want it I incorporate that test batch into the first production batch. For example, if my test batch is 5ml of 0mg (which it usually is) then when I make that first 50ml production batch I just reduce flavoring and 0mg unflavored by 10% and toss the test batch into that first 50ml bottle.

 

[babemomlover]

I think the easiest way to solve this would be to mix slightly larger (3-5mL) samples with no-nic.

Still really cheap. No need to skimp out, really. DIY is already cheap enough, and it's hard to get the accuracy you're looking for with cheapy equipment.

 

[Wishdog]

I leave the remainder of what I added previously to the mix in the syringe. Only the last flavor added has some skipped.

 

[Hoosier]

I don't use needles. The luer nose of the 1ml syringes go into the flavoring bottles without issue, heck the whole syringe goes in. The bit in the nose stays in the nose because I don't draw air in, so the unmeasured part never enters the juice. The flavoring syringe then goes into a cup of water and I get another one for the next flavoring.

But, I never experiment with less than 3ml for my test batches and sometimes that is too small when playing with stronger flavorings.

 

[favor1]

Thanks for all the information. I was reading a lot of Str8V8ping's posts and he states he uses the syringes without the needles as well, so that's what I think is the best choice. Although I feel like I'll be using up liquid a lot faster now (regarding mixing with the super concentrates). Ah, whatever, I guess I'll have to be more careful with flavors and not just toss them around mixing whatever crazy idea for a liquid I had in my mind (Huckleberry + 555 = nasty).

 

[favor1]

you can also change needles before you inject

True, but my syringe tips go on so tight it almost hurts prying them off 20 times in a row lol. I think I'll go syringeless and see how it works out. Although I'm a bit squeemish about the entire syringe accidentally going in to the PG or VG, considering everything that is on my hands goes into the PG or VG after that.

 

[B2L]

I have started using a 10 ml graduated cylinder instead of syringes. It is great for accuracy when mixing smaller samples or for measuring out the flavoring for larger 30 ml batches

 

[favor1]

You're using a plastic or glass grad. cylinder? I used to use glass but the meniscus was just annoying so I ended up getting a bunch of PE plastic graduated cylinders and they work fine and I don't have that meniscus.

 

[vsummer1]

Hello, I am a Registered Nurse and we use syringes to give precise doses of medications to our patients. The manufacturers of syringes have taken into account the amount in the needle as part of the measurement in small syringes (like the tuberculin you are using.) If you have a removable needle that did NOT come with the syringe, then it is usually removed prior to dosing a patient as we use blunt needles to draw from a vial and measure, then put on the appropriate needle if we are giving a shot or just into the IV as a needleless system.

So, if the needle + syringe is one unit, it measures what is in the needle. If you add a needle, the amount is not measured.

I hope this helps.

 

[favor1]

Hello, I am a Registered Nurse and we use syringes to give precise doses of medications to our patients. The manufacturers of syringes have taken into account the amount in the needle as part of the measurement in small syringes (like the tuberculin you are using.) If you have a removable needle that did NOT come with the syringe, then it is usually removed prior to dosing a patient as we use blunt needles to draw from a vial and measure, then put on the appropriate needle if we are giving a shot or just into the IV as a needleless system.

So, if the needle + syringe is one unit, it measures what is in the needle. If you add a needle, the amount is not measured.

I hope this helps.

Hmm, it seems thought that when I fill up my syringe (from the top through the plunger hole) to the 0ml line, and then fill another syringe to the 0ml line and then dump the liquid from one syringe to the other, it goes up to the .05ml line. I'm using a 21g needle so perhaps that's why. I think I'll be using it without the needle for measuring from now on.

Becton Dickinson Tuberculin 1 mL Syringe with Detachable Needle - Allegro Medical Supplies

 

[vsummer1]

Hmm, it seems thought that when I fill up my syringe (from the top through the plunger hole) to the 0ml line, and then fill another syringe to the 0ml line and then dump the liquid from one syringe to the other, it goes up to the .05ml line. I'm using a 21g needle so perhaps that's why. I think I'll be using it without the needle for measuring from now on.

Becton Dickinson Tuberculin 1 mL Syringe with Detachable Needle - Allegro Medical Supplies

If you can remove the needle, measure without the needle. If the needle is one unit, it is accounted for. We do not fill up our syringes from the plunger end.

edited to add: since the needle is not removable, you will lose some liquid in the needle when you toss it. This is accounted for in the syringe measurements, so you may have a tad more. I would suppose that when you are putting things in a vial you can get out the stuff in the needle, but with a human we can't very well get the last drops out of the needle.

 

[favor1]

I wouldn't feel safe if I saw a nurse filling up a syringe from the plunger end either

 

[favor1]

This is most likely the reason why I thought my RTS nicotine was hitting more like a 18mg strength when I was mixing @ 12mg, although it is probably slightly high still as I had to be adding more VG, PG, and flavors in my mixes as well.

 

[B2L]

You're using a plastic or glass grad. cylinder? I used to use glass but the meniscus was just annoying so I ended up getting a bunch of PE plastic graduated cylinders and they work fine and I don't have that meniscus.

10 ml is glass. I use it mostly for flavors and didnt want it to retain residual taste. I have a 50 ml plastic for measuring base and nic.

 

[Kurt]

The needle does not empty upon pushing the liquid out. Syringes deliver by difference volume. What's in the needle stays there. But then upon drawing up another liquid, the former liquid in the needle gets into the mix. One thing you can do without changing needles is to get some PGA and draw/flush with that between liquids. A few rapid pushes of the syringe after the PGA flush should get rid of the PGA by displacing it with air several times. Of course with such small amounts you are talking about it might linger a touch.

I agree with Hoosier: 1 mL might be too small to get all the details, which become big now, ironed out. If you are doing this with 100 mg nic, then yes you could have a nic uncertainty that large. of course, other things can make a nic hit harder, like thinning the juice. What is a better litmus is if you feel more nic internally, such as with rapid pulse and or sweating, after vaping it a while. And if its VG nic, there could still be small volumes of hot spots in the liquid. Drawing more will average this out some. Tough to keep nic uniform in pure VG.

 

[vimilla]

This thread just helped me understand measurements and syringes/cylinders a whole heaping bunch. I signed in to post a similar question, but thought beforehand that perhaps someone else had already asked my question. A simple search (well, advanced search, really) revealed not only did someone ask, but many answered.

Thanks to all who contributed to this thread... with such a knowledgeable bunch of folks around here, my less than a week old DIY training is going extremely well. Now back to vaping my yummy simple blueberries n cream DIY while I work in the "lab" on my Rainbow Sherbet!