Hey just a quick question, does anyone know how much liquid is held in a standard 14g needle for the syringes (wizard labs)? I know the needle is long and rather wide so i'm assuming it holds upwards of .1ml. Any answers would be awesome!
Edit: everyone thank you for the replies!
It doesn't matter what is contained within the needle. If you draw in 1 ml to the line and dispense all the way that is 1 ml. The syringe accounts for whats in the needle.
That isn't correct; needles vary in length and diameter and there's no way for the syringe to account for differences in needle volume.
It does not need to. Either the needle is empty before you fill, in which case there will be a tiny air bubble which is the last thing pushed back into the needle, or if there is anything in it before you draw, when you push down that same amount will be left in the needle. The vacuum created when you pull the plunger only pulls that volume of liquid into the syringe, and it can't force out liquid that's left in the needle after you've pushed all the way down.
The needle does matter. The 18g red ones hold .8ml
Try this. Pull back on your syringes. If you need .5ml, fill it up to .42ml. Tip it up, filling the rest of your syringe with air, and push air out. Bam. Exactly .5ml. If you don't take into account for the needle and filled to .5ml, you'd have .58ml.
Don't believe me, try for yourself
You can work it out using a quick bit of maths.
A 14g needle should have a 1.6mm internal diameter. You just need to measure its length and use the formula for the volume of a cylinder.
so 3.1415927 x 0.8^2 x length of needle
Volume of a cylinder is as you say πr^2 * h (or length), and a 14 gauge needle shows an inner diameter of 1.6mm, so r is .8mm. However we want to convert it to centimeters so the result is in cubic centimeters (an equivalent volume to milliliters), so divide r by 10, giving .08cm rather than .8mm.
π * .08cm * .08cm ~ .0201cm^2
So .0201 * the length of the needle in cm will give you volume in ml. Assuming a length of say 2 inches or 5cm, you're looking at .1ml.
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####	 Needle gauge comparison chart:
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>Hypodermic needles are available in a wide variety of outer diameters described by gauge numbers. Smaller gauge numbers indicate larger outer diameters. Inner diameter depends on both gauge and wall thickness. The following chart shows nominal inner diameter and wall thickness for regular-wall needles. Thin-wall needles (not shown) have identical outer diameters but larger inner diameters for a given gauge.
>Needle wire gauge is derived from the Birmingham Wire Gauge. #1 = 18½ B.W.G.; #2 = 19 B.W.G., and so on to #14 = 31 B.W.G.
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I just pull up a bit of air first, maybe .5ml. Then draw up more than I need, say .5ml. Then if I want only .1ml, I dispense from the .5 mark down to the .4 mark. Squirt the excess back into the bottle when done.
Of course, you have to have multiple syringes or clean the syringe thoroughly between flavors.