FAS-DPD Test

[elsie]

I need to order the FAS-DPD reagents. I have a decent quantity left over from last year's test kit I got from Ben, and they're still working fine, but since I heavily depend on this test to get accurate readings (the drop kit has never worked well for me and it still doesn't), I will need more as the summer moves forward. It doesn't make sense for me to buy a whole new test kit from Leslie's or some such store because I use the drop kit for pH of course, and I still have enough CYA solution to test the few times I need to this pool season, and I don't need to test for anything else. In last year's kit, they're called FAS-DPD #1, #2 and #3.

I did find on one pool's website:

Taylor R-0870 FAS DPD Powder for K-2006 and Taylor R-0871 FAS DPD Titrating Reagent for K-2006, and I do now recall from Ben's 2005 test kit that these are the right numbers, but what would be the third one, the one that measures for combined chlorine? If it's R-0872 (which would be logical), the particular website I've got pulled up doesn't have that one. Perhaps someone can steer me to a website that has all three, and also confirm that the equivalent to the FAS-DPD #3 is indeed R-0872?

I appreciate your help -

[CarlD]

You just want Taylor's reagent R-0003. It seems the DPD CC agent is the same for DPD and FAS-DPD testing.

You can go to Taylortechnologies.com and get the information directly.

Here's the instructions for the Taylor chems:
"1. Rinse and fill sample tube to desired mark with water to be tested.
NOTE: For 1 drop = 0.2 ppm, use 25 mL sample.For 1 drop = 0.5 ppm, use 10 mL sample.
2. Add 2 dippers R-0870 DPD Powder. Swirl until dissolved. Sample will turn pink if free chlorine is present.
NOTE: If pink color disappears, add R-0870 DPD Powder until color turns pink.
3. Add R-0871 FAS-DPD Titrating Reagent (chlorine) dropwise, swirling and counting after each drop, until color changes from pink to colorless. Always hold bottle in vertical position.
4. Multiply drops in Step 3 by drop equivalence (Step 1). Record as parts per million (ppm) free chlorine (FC).
5. Add 5 drops R-0003 DPD Reagent #3. Swirl to mix. Sample will turn pink if combined chlorine is present.
6. Add R-0871 FAS-DPD Titrating Reagent (chlorine) dropwise, swirling and counting after each drop, until color changes from pink to colorless. Always hold bottle in vertical position.
7. Multiply drops in Step 6 by drop equivalence (Step 1). Record as ppm combined chlorine (CC)."

[elsie]

Thanks so much Carl. Yes, it appears that R-872 is for bromine, the R-0003 for CL.

I see that all three numbers are listed multiple times with extra letters/numbers added, such as R-0003-A, R0003-A-24, R-0003-A144 etc. etc. When I drill down into each one I see it lists the same language, so I'm guessing that they are all the exact reagent, and that the different suffixes merely represent some type of cross-referencing.

There is one more thing you could help me with. I don't understand Step 1. of your instructions. It simply doesn't compute, i.e., what does it mean "For 1 drop = 0.2 ppm, use 25 mL sample. For 1 drop = 0.5 ppm, use 10 mL sample." I must not recall this from Ben's 2005 kit or we just didn't have the option. In any case, this will clearly become important because of the 'drop equivalence' in Step 4. Can you expound on for my brain block? Thanks again -

[GraceByDesign]

....
There is one more thing you could help me with. I don't understand Step 1. of your instructions. It simply doesn't compute, i.e., what does it mean "For 1 drop = 0.2 ppm, use 25 mL sample. For 1 drop = 0.5 ppm, use 10 mL sample." I must not recall this from Ben's 2005 kit or we just didn't have the option. In any case, this will clearly become important because of the 'drop equivalence' in Step 4. Can you expound on for my brain block? Thanks again -

If you use a 25ml sample, each drop you add in step 3 represents .2ppm FC (this is the 'drop equivanlece') so multiply # drops in step 3 by .2 to get ppm FC.
Same for step 7... for a 25 ml sample, drop equivalence is .2

If you use a 10ml sample, each drop represents .5ppm FC. This method requires fewer drops, but would also be slightly less accurate.

[CarlD]

I simply cut-and-pasted the directions directly from Taylor.

If you fill your sample tube to the 25 ml mark, each drop of titration fluid counts as .2 ppm. So you need 5 drops for each 1ppm.

If you fill to 10 ml, then each drop represents .5ppm and you need 2 drops for each 1ppm.

[elsie]

Ok you guyses, I get it. It's the same thing I do now. What threw me off was that the Taylor folk evidentally put this "note" smack underneath the first step, so my mind was trying to tie it in with that first step. Added to that was the word "multiply" when I use division for the FAS-DPD test. Of course, in this application, they are one and the same as long as you move the decimal point.

Thanks all for helping with this (and my cognitive deficit)! I truly appreciate it.

[dawndenise]

I see that all three numbers are listed multiple times with extra letters/numbers added, such as R-0003-A, R0003-A-24, R-0003-A144 etc. etc. When I drill down into each one I see it lists the same language, so I'm guessing that they are all the exact reagent, and that the different suffixes merely represent some type of cross-referencing.

Chem Geek did us all a great service when he searched out all those codes. Look for his post in this thread...

http://www.poolforum.com/pf2/showthr...reagent+refill

Watch out for those "A144"s!!!!!

[ivyleager]

I ordered several reagent vials and DPD-FAS powder on Tuesday from Taylor Industries.....it arrived this morning. Quick shipping!

CaryB

[elsie]

Ah, that's what the codes are all about. All good information! Thanks again to everyone.

[Tcap]

Hi,

I too needed the FAS-DPD reagents this year and got them from Taylor. Here are the three in the FAS-DPD kit -
R-0003-A DPD RGT #3; .75 OZ DB $3.25
R-0870-I DPD PDR; 10 GM V $7.65
R-0871-A FAS-DPD TTR''G RGT; .75 OZ DB $8.25

All three should come to: $19.15 + Shipping

I have ordered from taylor before and have been very pleased with them. Here's the website:
www.taylortechnologies.com