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Although both manufactured by Industrial Test Systems, Inc., a US based company in South Carolina, the DPD-1 ReagentStrip and SenSafe Free Chlorine Water Check products test for free chlorine residual in very different ways.
The chart below will explain the differences and similarities between the two free chlorine residual test methods:
DPD-1 ReagentStrips™ | SenSafe™ Free Chlorine Water Check | |
Detects: | Free Chlorine Residual (and Other Oxidizers Normally Tested Using DPD-1 Chemistry) | Free Chlorine Residual |
Test Procedure Overview: | Liberarting of DPD-1 Reagents Off Reagent Pads Into 10mL Sample and Checking Chlorine Concentration Visually by Color Comparator or Electronically Using a Colorimeter | Immersion of Test Strip in Water Sample, Removal of Test Strip After Specified Period of Time, and Visual Comparison of Developed Color in Test Area to a Color Chart |
Detection Range: | 0-6ppm | 0-6ppm |
Accuracy & Precision: | Depends on the Method Used to Interpret the Developed Color in the 10mL Sample. Visual Methods Will Have Less Precision Than Meters | 0, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.2, 1.5, 2, 2.6, 4, 6 ppm (mg/L) |
Certifications & Compliance: | DPD Testing as Specified in 4500-CL G
|
USEPA Approved Test Method for Free Chlorine
|
Number of Tests: | 100 Tests per Package | 50 Tests per Package |
Benefits: |
|
|
Per Unit Cost: | $15.99 per Package of 100 Tests | $15.99 per Bottle of 50 Tests |
As always, if monitoring free chlorine residual for reporting and/or compliance monitoring we suggest contacting your local health inspector before switching to a different chlorine testing method.
Although seemingly counter-intuitive, many methods approved on a Federal level may not have attained acceptance, yet, on a State or Local level.
]]>In the water business testing for free chlorine happens quite frequently (as Scott just said)… and we know of two ways to make that task easier:
While both testing methods make free chlorine residual testing much easier without losing accuracy, we highly suggest check with your State and Local inspectors first before using either product for compliance monitoring… because as you know (probably better than we do!), sometimes State/Local regulation changes do not always keep up with Federal Regulation changes.
Today’s inquiry deals with DPD for free chlorine testing and came to us from ‘Oviruo’ who asked, “please can you assit me to get dpd satchet powdered type for testing free chlorine in water. thanks.”
We did a quick check and found that you can purchase DPD-1 Powder Pillows for Free Chlorine Testing on the Hach Company web site. The material has an approximate cost of around $21 per 100 powder pillows.
Alternative to powder pillows
A company called Industrial Test Systems came out with an alternative to the powder pillow that performs as well or better than the powder pillow. They called it the ReagentStrip and it works quite well without the mess that sometimes accompanies the act of trying to pour a small packet of DPD powder into a sample vial.
Below you will see how the DPD-1 ReagentStrip works when used with the Hach 890 Water Testing Meter:
Free Chlorine Testing Using DPD-1 ReagentStrip
and Hach’s 890 Water Testing Meter
click on image to view larger version
According to the manufacturer, DPD-1 ReagentStrips work with chlorine testing meters manufactured by well-respected companies such as Hach®, LaMotte®, Orion®, WTW®, and others.
Additionally, the DPD-1 free chlorine testing procedure stands and an equivalent to USEPA method 330.5 for wastewater and Standard Method 4500-Cl G for drinking water when used with a Palintest Chlorometer 1000 water testing meter or equivalent.
Cost of DPD-1 ReagentStrips compared to powder pillows
Earlier in this article we mentioned that interested parties can pick up 100 DPD-1 powder pillows for around $21 on Hach’s web site.
For those interested in the DPD-1 ReagentStrips, you can purchase 100 of those for around $19 on FilterWater.Com.
]]>The US Environmental Protection Agency has set the Maximum Contaminant Level (MCL) for free chlorine at 4.0 parts per million, also known as milligrams per liter (mg/L).
The most commonly used test for free chlorine residual uses a reagent called DPD (what is DPD?). More specifically, it requires DPD-1 and DPD-1 comes in several different forms: liquid, powder, tablet and reagentstrip form.
Per the request of several men and women currently serving in the United States Armed Forces and other branches of the Unites States Government, we will begin posting possible alternate products for popular (established) NSN’s (National Stock Numbers) related to water quality testing.
NSN: 6550012191061, 6550014257957 — Chlorine Test Tablets
“DPD REAGENT TEST TABLETS FOR CHLORINE ANALYSIS. PACKAGED IN INCREMENTS OF 100. LAMOTTE.”
Alternatives:
eXact® Strip DPD ReagentStrips
Note: We have found that the products suggested above meet or exceed the specifications of the original NSN (National Stock Number) item. This does not mean, though, that you may substitute them in place of the item on a Government Contract. We provided the above information as possible sources of water quality testing products for consideration in future Contracts/Bids only.
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