Today’s inquiry comes to us from a woman serving her country in the United States Navy. ‘Ronda’ had a question about the DPD products she had seen on our web site.
“Do your DPD Chlorine tabs work in Hach equipment?”
Good afternoon, Ronda, and thank you for this inquiry. When weighing the different DPD options (tablets, powders, reagentstrips, etc.) make sure you note the sample size that each test method will work in. As a general rule most devices that use DPD as a reagent will have 10 mL sample sizes, but we have also seen devices that use 15 mL sample sizes, 7 mL sample sizes and 20 mL sample sizes.
Check your machine’s manual to find out what sample size it takes. In order to remain compliant with whatever drinking water directives you follow you will need to match up the sample size w/ the correct reagent amount.
Specifically, though, you asked about the DPD tablets for chlorine testing that we have shown on our site and as far as we know all of the DPD products we have shown on our site work for 10 mL samples — except for the eXact Micro DPD products which work in smaller samples.
Two 10-mL Tablets/Strips/Powders for a 20-mL Sample?
While in theory that would work, definitely check your approved testing method to see if it expressly forbids that sort of thing and/or if it specifically calls for a brand or type of chlorine reagent delivery method. In the past we have seen where testing protocols have gotten so granular that they call out not only the type of DPD used, but also the brand of the test meter and DPD used for chlorine testing.