High dead space in syringes

[Mayhem987654]

Low dead space syringe - Wikipedia

Hello I was wondering if anyone has ever considered the high dead space in the syringe when mixing. The fluid in the needle has to account for enough fluid to throw off the recipe, considering all the different gauges of there. I'm not so concerned about the flavoring as much as nicotine. Just wondering if anyone has come up with a solution or a method to solve it. It's hard to determine how much is in there. I don't use a scale at this time but I may consider it. Thanks

 

[zoiDman]

Low dead space syringe - Wikipedia

Hello I was wondering if anyone has ever considered the high dead space in the syringe when mixing. The fluid in the needle has to account for enough fluid to throw off the recipe, considering all the different gauges of there. I'm not so concerned about the flavoring as much as nicotine. Just wondering if anyone has come up with a solution or a method to solve it. It's hard to determine how much is in there. I don't use a scale at this time but I may consider it. Thanks

If I want to Dispense say 1.5ml from a Syringe, then draw 2.5ml into the syringe, if I push the Plunger until I get to the 1ml line, do I need to be Concerned with the amount of "Dead Space" my syringe May or May Not have?

 

[retired1]

The only time I use a needle is when I'm filling the tank. When you're mixing in your bottles, there's really no need to use a needle on your syringes.

 

[SteveS45]

Instead of being concerned with how much liquid is in the needle itself it is more of a concern to get the correct ML line in the syringe itself. At least in my opinion.

Check how many drops next time for a comparison.

 

[Hawise]

Syringes are designed to account for the dead space. If you draw up to the 2 ml mark and then push the plunger, you'll dispense 2 ml. You'll lose a little flavouring/nic, but the amount going into the recipe will be correct.

 

[Eskie]

It's not the syringe that makes for low dead space, it's actually the needle. As low dead space needles are usually ~30G or smaller, you'll have a heck of a time with a viscous liquid. As we use 14G needles (if we use needles at all) it doesn't apply.

And as @Hawise pointed out as I was distracted while writing one sentence, the amount delivered will be consistent regardless the amount that remains in the needle, unless you're dealing with teeny tiny volume where a few µl really matters. For us it doesn't

 

[Dougiestyle]

I have a 14ga 3" needle on my 10ml syringe, and the needle holds .4ml. I account for this in measuring.

The way to alleviate the excess needle capacity is to draw the desired amount. Remove the syringe from the liquid. Continue drawing until air is entering the syringe. Dispense excess back into the container it came from until the plunger is back at the desired amount. Once or twice doing this will tell you how much excess your needle holds.

 

[JCinFLA]

The fluid in the needle has to account for enough fluid to throw off the recipe, considering all the different gauges of there. I'm not so concerned about the flavoring as much as nicotine.

IMO, the blunt needle tips don't hold enough flavoring or nic to throw off a recipe by any amount to be concerned with. It's never affected my recipes that I could tell.

They do make blunt needle tips that are only about 1 1/4" long in total, including the Luer Lock plastic part of it. I bought some at FT, and there's hardly any liquid that remains in them after you push the plunger all the way down. I usually push it down 2-3 times to get as much as possible out.

$0.91 14G Dispensing Refilling Needle for RTA Atomizer (20-Pack) 20-pack - plastic + stainless steel / 2.11mm outer dia. / 1.69mm inner dia. at FastTech - Worldwide Free Shipping

Or, as @retired1 said above...just don't use a needle tip on the syringe when drawing your liquids out. Works just as well, as long as the opening of the bottle is big enough.

 

[Hawise]

The way to alleviate the excess needle capacity is to draw the desired amount. Remove the syringe from the liquid. Continue drawing until air is entering the syringe. Dispense excess back into the container it came from until the plunger is back at the desired amount. Once or twice doing this will tell you how much excess your needle holds.

It doesn't actually matter how much the needle holds if you're concerned about accuracy. Think of it this way: You fill the syringe. The syringe is full (to the point you want - say to 2.3 ml) and the needle is full. The 2.3 ml is the bit in the syringe. The fluid in the needle (0.4 ml in your case) is extra - you've actually drawn up 2.7 ml. Then you press the plunger. The syringe dispenses 2.3 ml - the 2.3 ml you measured. There's still 0.4 ml in the needle, but that's fine because it doesn't affect the measurement.

If you look at the original Wikipedia link, you'll see that the concern is about waste - the 0.4 ml in the needle - not about accurate measurement.

 

[Mayhem987654]

IMO, the blunt needle tips don't hold enough flavoring or nic to throw off a recipe by any amount to be concerned with. It's never affected my recipes that I could tell.

They do make blunt needle tips that are only about 1 3/8" long in total, including the Luer Lock plastic part of it. I bought some at FT, and there's hardly any liquid that remains in them after you push the plunger all the way down. I usually push it down 2-3 times to get as much as possible out.

$0.91 14G Dispensing Refilling Needle for RTA Atomizer (20-Pack) 20-pack - plastic + stainless steel / 2.11mm outer dia. / 1.69mm inner dia. at FastTech - Worldwide Free Shipping

Or, as @retired1 said above...just don't use a needle tip on the syringe when drawing your liquids out. Works just as well, as long as the opening of the bottle is big enough.

Awesome. Thank you I was stressing over it.lol

 

[Dougiestyle]

It doesn't actually matter how much the needle holds if you're concerned about accuracy. Think of it this way: You fill the syringe. The syringe is full (to the point you want - say to 2.3 ml) and the needle is full. The 2.3 ml is the bit in the syringe. The fluid in the needle (0.4 ml in your case) is extra - you've actually drawn up 2.7 ml. Then you press the plunger. The syringe dispenses 2.3 ml - the 2.3 ml you measured. There's still 0.4 ml in the needle, but that's fine because it doesn't affect the measurement.

If you look at the original Wikipedia link, you'll see that the concern is about waste - the 0.4 ml in the needle - not about accurate measurement.

Gotcha. That makes sense. When dispensing my flavors, etc, I usually "clear" the needle into the mix with one or two pumps of air with the plunger. With this tactic and my big ol needle, I can account for the .4ml in the needle by drawing .4 less than spec'd. Same difference, but no waste my way.

 

[Hawise]

Gotcha. That makes sense. When dispensing my flavors, etc, I usually "clear" the needle into the mix with one or two pumps of air with the plunger. With this tactic and my big ol needle, I can account for the .4ml in the needle by drawing .4 less than spec'd. Same difference, but no waste my way.

Yup, that would work.

 

[Eskie]

I have a 14ga 3" needle on my 10ml syringe, and the needle holds .4ml. I account for this in measuring.

The way to alleviate the excess needle capacity is to draw the desired amount. Remove the syringe from the liquid. Continue drawing until air is entering the syringe. Dispense excess back into the container it came from until the plunger is back at the desired amount. Once or twice doing this will tell you how much excess your needle holds.

Are you sure it's that much? A 14G needle has a 1.6 mm ID. 3 inches is 76 mm. A cylinder 76 mm long with a radius of 0.8 would be 152 mm², or 0.152 ml (if my math is correct). Still a bit of dead space, but not all that much.

 

[Mayhem987654]

It doesn't actually matter how much the needle holds if you're concerned about accuracy. Think of it this way: You fill the syringe. The syringe is full (to the point you want - say to 2.3 ml) and the needle is full. The 2.3 ml is the bit in the syringe. The fluid in the needle (0.4 ml in your case) is extra - you've actually drawn up 2.7 ml. Then you press the plunger. The syringe dispenses 2.3 ml - the 2.3 ml you measured. There's still 0.4 ml in the needle, but that's fine because it doesn't affect the measurement.

If you look at the original Wikipedia link, you'll see that the concern is about waste - the 0.4 ml in the needle - not about accurate measurement.

Thank you so much, I'm ready to go

 

[zoiDman]

Are you sure it's that much? A 14G needle has a 1.6 mm ID. 3 inches is 76 mm. A cylinder 76 mm long with a radius of 0.8 would be 152 mm², or 0.152 ml (if my math is correct). Still a bit of dead space, but not all that much.

In a Luer Lock Syringe/Needle, the Needle Base can have Quite a Bit of Dead Space. As well as the Inside Taper of the Syringe Base.

If you have a Luer Lock Syringe/Needle laying around, hold it up to a Bright Light and you will see what I mean.

Could account for some of that Missing "Math".

 

[Mayhem987654]

In a Luer Lock Syringe/Needle, the Needle Base can have Quite a Bit of Dead Space. As well as the Inside Taper of the Syringe Base.

If you have a Luer Lock Syringe/Needle laying around, hold it up to a Bright Light and you will see what I mean.

Could account for some of that Missing "Math".

It seems to me to be quite alot of fluid. I'll have to do some research to see how much more is in it. I'll make a couple of small bottles to see the difference,if any in flavor and throat hit.

 

[retired1]

Or, as @retired1 said above...just don't use a needle tip on the syringe when drawing your liquids out. Works just as well, as long as the opening of the bottle is big enough.

Or, just remove the plunger, cap the end, and pour directly into the syringe.

 

[Jdurand]

Seems to me the "dead space", accounted for or not, will be proportionally the same for each ingredient. So while the actual ML count may be off, the proportions of the recipe should be accurate.

This really was one of my determining factors of switching over to mixing by weight. That and the super quick set up to clean up time.

 

[SteveS45]

I see many members mentioning removing the plungers but the syringes I buy do not come apart.

 

[mhertz]

Indeed, I had the same issue in the past. I read this great tip, and then the darn ones i've choosen to buy of course didn't support that neat trick. Well, maybe it just took alot of brute force, but I didn't try past normal semi-strong pressure. Great trick nonetheless, to use the syringe as a graduated cylinder kinda. If mixing into destination-bottle with a syringe like that, then all left to clean afterwards is one single syringe, regardless of multi-flavor recipe. Nice (Of course one syringe could be used for multi-flavor recipe also by just cleaning the syringe inbetween flavors, but the previous method sounds nicer to me imho)