Reef Chemistry Question of the Day #161 Using a Syringe

[Randy Holmes-Farley]

Ahh ok. Completely understood now! Thanks Amigo!

You're welcome.

Happy Reefing.

 

[Alfrareef]

Good. Now it's clear... and thinking about it it's logic.

 

[kodo28]

@Randy...I just saw this thread and I have a question concerning the type of syringe.
Some RedSea test kits come with a different type of Plunger piston on their syringe.

Would this be an issue ?
Another thing, sometimes when I start to draw fluid in the barrel until the end 1ml mark I will have liquid up to 0.8ml and sometime I will have it at 0.83 or even 0.85 this as no incidence on the test it self right ?

Thanks

 

[Joel B in FL]

I have the same issue. Sometimes when I fill my syringe if I go to the 1ml mark with the plunger then I have .85 of actual fluid and other times I have .83. It hardly ever seems to hit a consistent mark every time. This is why I look at the starting and ending point of the fluid in the barrel instead of the plunger. Of course you can only use this method if you do not empty the syringe entirely while measuring. So for example if the starting point of the fluid is .85 and the ending point if .14 then you have used .71ml of fluid regardless of what the starting and ending points of your plunger are.

 

[Randy Holmes-Farley]

@Randy...I just saw this thread and I have a question concerning the type of syringe.
Some RedSea test kits come with a different type of Plunger piston on their syringe.

Would this be an issue ?
Another thing, sometimes when I start to draw fluid in the barrel until the end 1ml mark I will have liquid up to 0.8ml and sometime I will have it at 0.83 or even 0.85 this as no incidence on the test it self right ?

Thanks

The shape of the plunger won't impact the answer. It is still only the movement of the plunger that matters. The tightness of the tip (and hence the air volume) may impact how much appears in the barrel (even with a pointed plunger), but the total liquid sucked up and dispensed shouldn't change.

 

[Randy Holmes-Farley]

I have the same issue. Sometimes when I fill my syringe if I go to the 1ml mark with the plunger then I have .85 of actual fluid and other times I have .83. It hardly ever seems to hit a consistent mark every time. This is why I look at the starting and ending point of the fluid in the barrel instead of the plunger. Of course you can only use this method if you do not empty the syringe entirely while measuring. So for example if the starting point of the fluid is .85 and the ending point if .14 then you have used .71ml of fluid regardless of what the starting and ending points of your plunger are.

That is likely the tip air volume changing, but if so, it doesn't alter the fluid sucked up and/or dispensed. That said, it is OK to track the liquid level instead of the plunger tip if you want, and as you said, if you know you will not dispense it all. In general, such corrections should not improve the quality fo the answer.

 

[kodo28]

The shape of the plunger won't impact the answer. It is still only the movement of the plunger that matters. The tightness of the tip (and hence the air volume) may impact how much appears in the barrel (even with a pointed plunger), but the total liquid sucked up and dispensed shouldn't change.

Thanks a lot Randy

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.

 

[Daltrey]

Bumping to the top. This is very helpful. Thanks

 

[MnFish1]

B

 

[Randy Holmes-Farley]

Bumping to the top. This is very helpful. Thanks

I'm glad you liked it.

Happy Reefing.

 

[Cory]

So does the tip have 1.3 ml in it?

 

[Randy Holmes-Farley]

So does the tip have 1.3 ml in it?

If you are talking about the original question, that about right. The tip (including a bit of the syringe body below the plunger when it is pushed all the way to zero) looks to be about 1.3 mL, which can be read from the air gap volume difference between the top of the liquid and the bottom of the syringe plunger.

 

[orr2003]

That is likely the tip air volume changing, but if so, it doesn't alter the fluid sucked up and/or dispensed. That said, it is OK to track the liquid level instead of the plunger tip if you want, and as you said, if you know you will not dispense it all. In general, such corrections should not improve the quality fo the answer.

This is exactly why I dont use the tips that come with the syringes. Over the years I have noticed an inconsistency in the amount of reagant drawn into the syringe due to volume of air in the tip changing from time to time. So I just pull up some reagant and while holding the tip still submerged in the reagant push up and down on the plunger until I expel all the air in the tip of the syringe. Then just pull up 1ml of reagant and there is no air in the syringe to think about.

But after thinking about it I guess it doesnt matter the the fuild level if I use the tip adn pull to the 1ml mark there is still 1ml of reagant it was just that the air volume changes

 

[Randy Holmes-Farley]

This is exactly why I dont use the tips that come with the syringes. Over the years I have noticed an inconsistency in the amount of reagant drawn into the syringe due to volume of air in the tip changing from time to time. So I just pull up some reagant and while holding the tip still submerged in the reagant push up and down on the plunger until I expel all the air in the tip of the syringe. Then just pull up 1ml of reagant and there is no air in the syringe to think about.

Why? The amount of liquid in the syringe is not important, and is the reason for this question.

It makes no difference what the tip volume is. The syringe will work exactly as needed even if the tip volume was 100 liters and no liquid ever entered the syringe barrel.

 

[orr2003]

Why? The amount of liquid in the syringe is not important, and is the reason for this question.

It makes no difference what the tip volume is. The syringe will work exactly as needed even if the tip volume was 100 liters and no liquid ever entered the syringe barrel.

Yeah I was editing my post as your were commenting. LOL

 

[orr2003]

Why? The amount of liquid in the syringe is not important, and is the reason for this question.

It makes no difference what the tip volume is. The syringe will work exactly as needed even if the tip volume was 100 liters and no liquid ever entered the syringe barrel.

My reasoning has always been that if the tip is not completely submerged I could be pulling air into the barrel from around the tip while pulling up the reagant.

 

[MnFish1]

Curious - why use a syringe with a tip at all? (especially like the one in the example where its measuring CC volumes)? There is a risk of air going into the syringe if the tip has a small leak (unless submerged) - especially if its been taken off and put on multiple times.

 

[Randy Holmes-Farley]

My reasoning has always been that if the tip is not completely submerged I could be pulling air into the barrel from around the tip while pulling up the reagant.

If that happened, it would be a problem, I agree.

 

[orr2003]

Curious - why use a syringe with a tip at all? (especially like the one in the example where its measuring CC volumes)? There is a risk of air going into the syringe if the tip has a small leak (unless submerged) - especially if its been taken off and put on multiple times.

That was the point I was trying to make