High dead space in syringes

[anavidfan]

And I thought I was the only "weirdo" to think about the space and the lines etc.

I asked the same thing in my classes for surgical tech... I got those rolling eyes from instructors, obviously I was not the first to ask..... But got this remark. They are all designed to compensate for this.... Just pull the plunger to draw the liquid and then eject tap and draw again,... Thats why people ( doctors, nurses, etc) tap to get any air out.

Then I asked should the measurement be done using the bottom of black rubber stopper or the top of it?
Glares again.... I was told to use the bottom of black plunger as the guide to the volume lines.

Now my cynical mind wonders, are there some companies that are more accurate than others? Again the same rolling eyes from the instructors..... The same rolling eyes while in catholic school about so many things.... basically shad-up and do as told and stop asking.....

I do the draw of the liquid/flavor/ nic a couple times, tap and draw again and no air pockets. This is our eliquid not life or death medicine/drug dispensing.....

 

[puffon]

The same rolling eyes while in catholic school about so many things.... basically shad-up and do as told and stop asking.....

At least they didn't give you the "WACK" with the ruler...

 

[zoiDman]

... Thats why people ( doctors, nurses, etc) tap to get any air out.

...

Wow... And all this time I Thought it was so my Doctor wouldn't put a Air Bubble into my Vein. One that might work it's way to my Brain.

 

[anavidfan]

Wow... And all this time I Thought it was so my Doctor wouldn't put a Air Bubble into my Vein. One that might work it's way to my Brain.

Well, whats one tiny little air bubble going to do to my brain......That I havent done to it myself

 

[zoiDman]

Well, whats one tiny little air bubble going to do to my brain......That I havent done to it myself

Yeah... What's the Worst that can happen?

 

[jpasint]

Well, whats one tiny little air bubble going to do to my brain......That I havent done to it myself

Agreed. Twisted minds, I mean great minds, think alike.

 

[jpasint]

I can say that I have experimented with this head/dead space topic using water as the test liquid. I used water only because it was easier to work with while testing.

You only need to draw the plunger up to the required ml mark regardless of how much air you see (or don't see) between the plunger and the actual liquid. If you draw the liquid itself up the required ml mark and there is air/space between the liquid and the plunger, you will definitely be over on your measurement. How much over is dependent on the size/capacity of the needle you are using plus the head/dead space at the tip of the syringe. Between the two, it can be enough to throw off your recipe if the desired amount is low enough. I’ve made plenty of small 15ml test recipes and many of the flavors required only 0.150 ml or less. At that minute amount, there is not much error required to have the entire recipe thrown off. Especially considering that many of the low percentage flavors added to a recipe are often the really strong ones like AP.

Of course, in order to be accurate one way or the other, this assumes that pressures have leveled and there is not a vacuum within the syringe, say like if you were trying to draw VG through an 18-gauge needle. You’d probably have to wait a week (if even possible at all) for the VG to actually fill the syringe to the desired level and there would be a vacuum until equilibrium was established. It obviously is not possible to be very accurate if a vacuum exists.

I left all of these concerns regarding syringes and needles behind when I decided to start mixing by weight. Mixing by weight too has a variable of accuracy due to not having the exact specific gravity of each of my flavors. I know I could look them all up and enter them into HotRod19579's Juice Calculator but I don’t really plan on doing that since 1.038g p/ml is plenty close enough for my mixing style.

All of this has just been my experience and is not based on any “true” scientific facts or testing.

 

[Frenchfry1942]

Science class or medical class teach how to measure correctly with a syringe. Obviously it is different when injecting into a body area that cannot accept air, but we don't do that with vaping. Just draw extra air into the needle, pulling any liquid out of the needle itself and use the measurement lines on the syringe.

Again, using a syringe in DIY can be very different than using a syringe in a medical situation.

Be safe.

Edit: oops, I didn't notice there was a page 2.