dropper tip opening too large?

[rhythm]

I just started using a new 2 oz bottle of the FAS-DPD titrating reagent, and I've noticed that when I turn the bottle completely upside down, a drop will quickly form and fall down into my sample without me squeezing the bottle at all. Sometimes it looks like a second one will also form and fall into the sample if I'm not quick at turning the bottle back upright. I hadn't run into this before; I've always had to apply at least a tiny bit of pressure each time to get a drop out. Is this normal, or is it possible that the dropper tip opening is a bit too large?

Thanks,
Greg

 

[rhythm]

I'm going to bump this back up with a follow-up question....

Have any of you had the same situation....reagent bottles where the drops will form and come out on their own from simply tipping the bottle upside down (no pressure from your own fingers on the bottle)? If so, did it seem that you were getting the same amount in your drops as normal? I'm questioning my latest results a bit on my chlorine tests (my FC readings are lower than I'd expect based on how much I'm adding each day), and wondering if my titrating reagent drops are too large. Anyone?

In case you're wondering, I'm referring to the Taylor R-0871 titrating reagent in the 2 oz bottle.

Thanks,
Greg

 

[rhythm]

Oh...one more thing I thought of asking....

On the Taylor reagent bottles, can I remove the dropper tip and replace with another one? I have read that you can do this with the TF-100 kit bottles, but I wasn't sure if this was the case with the Taylor ones. If I can, I'll just swap tips with another reagent (I still have the original bottles of acid and base demand, which I don't care about, so I'll use a tip from one of those). Then I can see if I get the same reading as I'm getting right now with my current bottle of FC titrating solution.

Thanks,
Greg

 

[JasonLion]

Yes, you can swap the tips. Make sure you clean them throughly before putting them on the other bottle.

I occasionally get a drop that come out without any effort on my part, but usually just once when first using a reagent that has been stored on its side.

 

[rhythm]

I took the dropper tip off of a bottle of base demand (that I'm getting rid of anyway) and put it on my new 2 oz bottle of FAS-DPD titrating reagent. I rinsed the dropper tip in a stream of tap water for about a minute (is that sufficient to clean it?).

Anyway, it behaved the same way once I put it on titrating reagent, and the results I got were just about the same. So I'm wondering if the larger bottle has something to do with it, at least while it's still nearly full. Perhaps the extra volume of liquid forces the drops out easier....I don't know. I did confirm ahead of time that the dropper tip required light squeezing to get a drop out while it was still on the 3/4 oz bottle of base demand. Anyway, I'll just leave this tip on there and continue on, since it seems that a different dropper tip didn't change anything.

I'm questioning the titrating reagent itself a bit because of the readings I've received recently, but I'll post something about that in a new thread.

 

[Pool in Carolina Blue]

I took the dropper tip off of a bottle of base demand (that I'm getting rid of anyway) and put it on my new 2 oz bottle of FAS-DPD titrating reagent. I rinsed the dropper tip in a stream of tap water for about a minute (is that sufficient to clean it?).

Anyway, it behaved the same way once I put it on titrating reagent, and the results I got were just about the same. So I'm wondering if the larger bottle has something to do with it, at least while it's still nearly full. Perhaps the extra volume of liquid forces the drops out easier....I don't know. I did confirm ahead of time that the dropper tip required light squeezing to get a drop out while it was still on the 3/4 oz bottle of base demand. Anyway, I'll just leave this tip on there and continue on, since it seems that a different dropper tip didn't change anything.

I'm questioning the titrating reagent itself a bit because of the readings I've received recently, but I'll post something about that in a new thread.

I previously posted a response but it didn't show up for some reason. Anyway, I also have the same problem with all of my 2 oz. bottles. For this reason, I have decided to go back to the .75 oz. As you suggested, I think it is the extra weight of the fluid. While the smaller bottles cost more per unit, it saves me the aggravation.

 

[duraleigh]

Nothing scientific, but I would agree anecdotally with ya'lls assessment of the 2 oz bottles. I experimented with them some and always felt like they were a little too willing to give up the drops.

FWIW, those bottle are available in three flexibilties (LDPE,(low density polyethelene, etc.) MDPE, and HDPE)

The LDPE's work nicely on 1 oz or less bottles, the MDPE's do Okay but are too ridgid onanything less than an oz and the HDPE's are almost impossible to squeeze on anything less than 2 oz.

In short, It's a balancing act trying to find the right size and rigidity of bottle for the fluid being dispensed and each selection is usually a bit of a compromise.

 

[rhythm]

Thanks for the input; sounds like you both ran into the same thing I did.

Since the price is better on the 2 oz bottles, what I may do from now on is buy it in 2 oz sizes but keep a 3/4 oz bottle for performing the tests. The dropper tips seem to be easy enough to remove and put back on, so it would probably be pretty easy to go that route.

Greg