Chlorine Test Paper

Chlorine Test Paper

The Chlorine Test Paper measures total available chlorine from 0-200ppm, and give results in just seconds. Total available chlorine is the sum of free available chlorine and the combined available chlorine. Our chlorine test paper is most often used to test the strength of solutions used to sanitize surfaces, for example, in the restaurant industry. In these types of applications, bleach is usually used to generate the available chlorine.

SKU: 145 Categories: , Tag:

Chlorine Test Paper

When using bleach as a cleaner, it must be diluted before use, and it will work best in the pH range of 5-7.

  1. Use dry fingers to remove a chlorine test paper strip from the vial.
  2. Dip the test strip into the solution to be tested, and do not agitate.
  3. Remove and compare to the color chart immediately.

NOTE: The strip will darken over time, so it is best to compare to the color chart as directed. In addition, if two strips are stuck together, the color will be darker. Lastly, if you lay the strip against the vial when comparing to the color chart, it will also darken the color. The color chart was created by holding a strip in the air next to the vial.

NOTE: If you believe that the solution contains chlorine, but the test the strip is white after dipping, you may be seeing what is referred to as the “bleaching out effect.” At high concentrations of bleach, the available chlorine will overwhelm the indicators used in the strips. If this happens, instead of developing a purple color the strip will very quickly turn to white. The best indicator of this effect is the presence of a thin blue line on the strip separating the wet portion from the dry portion of the strip.

JD145; JG145; 145/500; 145/VIAL; 145; 145-12V-100; 145-25V-100; 145-144V-100; 145-500V-100; 345-1-10

Product Specs

SKU 1:

145-12V-100 (12 vials, 100 strips/vial)

SKU 2:

145-25V-100 (25 vials, 100 strips/vial)

SKU 3:

145-144V-100 (144 vials, 100 strips/vial)

SKU 4:

145-500V-100 (500 vials, 100 strips/vial)

Strip Quantity:

100 strips

Vial Dimensions:

.75″ (D) x 2.75″ (H) [19mm (D) x 70mm (H)]

Strip Dimensions:

1.875" (L) x .25" (W) [48mm (L) x 6mm (W)]

Box Dimensions:

10" x 10" x 2.75" [29.8 cm x 19 cm x 7 cm] (144-pack box), 21" x 14.75" x 3" [53.3 cm x 37.5 cm x 7.6 cm] (500-pack box), 3.25" x 2.375" x 3" [8.3 cm x 6 cm x 7.6cm] (12-pack box), 5" x 3.5" x 3" [12.7 cm x 8.9 cm x 7.6 cm] (25-pack box)

Weight:

0.02 lbs [9 g] (single vial)

Shelf-Life:

2 Years

Label:

Customizable Label

Other:

Stored in a pocket-sized, lightweight vial.

Do certain chlorine test strips work better with trichloramines?

Yes. For example, or Chlorine paper (10-200ppm) will get a good reading, but the Mid-Level chlorine plastic strip (0-200ppm) will not work with trichloramines.

The difference is explained by the “type” of chlorine that each strip reacts to.

The paper strip is based on the potassium iodide starch reaction and will react to both “free” and “total” chlorine. The Mid-Level plastic chlorine test strip uses a red-ox indicator and only reacts to “free” chlorine.

“Free” chlorine is the combination of hypochlorous acid and hypochlorite present in the solution. The amount of each is dependent on the pH of the solution. At neutral pH and lower, the hypochlorous acid form dominates.

“Total” chlorine is the combination of “free” chlorine and “combined” chlorine (chlorine combined with ammonia to form monochloramine, dichloramine, and trichloramine).

Therefore, if you are monitoring solutions containing chloramines, you should use the paper chlorine strips. To get any response with the plastic strips, you would have to add much more chlorine.

How are the chlorine test papers affected by pH?

The 0-200 ppm chlorine test paper (145) performs best in neutral pH solutions (pH 6-8). High pH may slightly suppress the color development resulting in slightly lower results. Acidic waters do not appear to affect the color development.

What do your chlorine test papers actually detect?

Our chlorine test papers are based on the potassium iodide starch reaction. As such, many oxidizing species will cause the paper to turn purple. The iodide that is impregnated in the paper is oxidized to iodine when exposed to a solution containing an oxidizer. The iodine then complexes with the starch (also impregnated in the paper) and turns the paper blue/purple. The iodide and starch impregnated into the paper are in excess, so that the intensity of the color developed depends on the amount and strength of the oxidizing species.

Can I use the chlorine test papers to measure concentrations using splashless or scented varieties of bleach?

It is not advisable to use our chlorine test papers to measure chlorine concentrations made with non-regular bleach.

Non-regular bleach will turn the test paper blue/purple, however, the bleach formula contains additives that influence the color development of the strips and also affects the results of the verification methods.

What color chart should I use forthe 345 chlorine books?

If you are using the 345 chlorine books to measure chlorine levels, you should use the same chart as the 145 chlorine test papers.

Do the 145 chlorine test papers change color beyond 200ppm?

The colors for the 10, 50, 100, 200 ppm chlorine will be the same progressively more purple color. Above 200 ppm the purple will intensify further to the point that it will appear almost black.

At some point – usually above 1000 ppm the strip will actually bleach out and instead of purple it will be white. When this happens some users think that this means they have no available chlorine present when in fact they have too much and it overwhelms the chemistry on the strip. The tell-tale sign of this is the presence of a purple stripe at the sample-paper interface. You can demonstrate this to yourself by dipping a strip in straight bleach.

How do I determine the recommended bleach concentration for a certain product?

To determine the recommended bleach concentration for your application, locate the EPA registration number on your product label. Visit the EPA’s website, and enter the EPA Registration Number, then click Search. You should see the details about the product, and beneath that, a PDF bearing the date that this product was registered by the EPA (if there is a list, the PDF at the top of the list should show the most recent approval). Click on that most recently-approved PDF. The PDF should come up on your screen. Scroll down to the section that shows the directions for using the product as a sanitizer or disinfectant. Follow the directions listed for your intended use.

How is the chlorine test paper (145) color chart developed?

Each printing of color charts is preceded by an extensive review of the test strip performance. Chlorine standards are generated at 10, 50, 100, and 200ppm. These values are confirmed by at least one independent test method. Using these verified standards, samples of strips from several different production runs are used to determine the color associated with each standard value. Once the colors are selected, the color charts are printed. Prior to their use, the color charts are again checked with a fresh set of verified standards. After acceptance of the color charts, subsequent production runs of test papers are checked against the charts before they are packaged for sale.

Does the temperature of my chlorine solution affect chlorine test paper (145) performance?

Temperature will slightly affect the performance. The 145 chlorine test papers (0-200ppm) have been checked in solutions up to 70°C (158°F). At temperatures above 50°C, a 10ppm solution will not develop as much color as it should, resulting in a reading lower than expected. Solutions of 50, 100, and 200ppm chlorine appear to be influenced less. For practical purposes, solutions greater than 50ppm are not noticeably influenced by temperature.

How do I select the correct chlorine test strip?

Chlorine is one of the most popular chemicals for cleaning, sanitizing, and disinfecting. Two common examples will help illustrate this. Swimming pools are often treated with chlorine chemicals. In this application, the amount of chlorine needed is low, typically only 1-3ppm chlorine. On the other hand, disinfection of daycare and hospital facilities requires a much higher chlorine level, typically 600-1200ppm. In both examples, the 0-200ppm chlorine test paper is not the best choice. Precision Laboratories manufactures a whole range of chlorine test strips. Please consult our product listing for the chlorine test strip that best matches your application.

How do I make up a sanitizing solution at 200ppm?

There are many online calculators that can help with this. A general rule of thumb is that 1 tablespoon of bleach in 1 gallon of water will yield a solution that is approximately 200 ppm in available chlorine. It is important to note that this is true if the starting bleach is normal bleach (5.25% sodium hypochlorite which is equivalent to 5% available chlorine). Today, bleach is often sold in concentrated form (8.25% sodium hypochlorite which is equivalent to 7.85% available chlorine). It is best to check the label. Another consideration is the age of the bleach. Bleach will lose potency over time, especially if the bottle has been opened several times.

What affects the intensity of hte purple color when using the chlorine test paper (145)?

The chlorine test paper will darken over time, so it is best to compare the color as directed (immediately after dipping into solution). Also, be aware that if two strips are stuck together, the color of the paper will be darker. Lastly, be careful not the lay the strip against the vial when comparing to the color chart, as this will also intensify the color. The chart provided was created holding the strip in the air next to the vial.

What is the ideal pH of an available chlorine solution?

All available chlorine has some biocide strength, although hypochlorous acid is a far stronger biocide than hypochlorite ion or the chloramines. In solutions at pH of 5-7, hypochlorous acid is the most prevalent species. For this reason, most sanitizing solutions will work best in the neutral to slightly acidic pH range.

What is the difference between free available, combined available, and total available chlorine?

When chlorine gas (Cl2) or bleach (sodium hypochlorite or NaOCl) is added to water the result is the formation of hypochlorous acid (HClO).

Cl2 + H2O -> HOCl + H+ + Cl-

NaOCl +H2O -> HOCl + Na+ + OH-

Depending on the pH of the solution the hypochlorous acid exists in solution as either hypochlorous acid (HClO) or hypochlorite ion (OCl-).

HOCl OCl- + H+

Free available chlorine refers to the amount of hypochlorous acid AND hypochlorite ions present.

Combined (or bound) available chlorine arises when nitrogen (usually in the form of ammonia) is present to form what are called chloramines (mono-, di-, and trichloramines are possible).

Total available chlorine is the sum of the free available chlorine and the combined available chlorine.

Why isn't the 145 Chlorine test paper working?

If you believe that the solution you are using contains chlorine and yet after testing it with chlorine test paper, the strip is still white, you may be seeing what is referred to as the “bleaching out effect.” At high concentrations of bleach, the available chlorine will overwhelm the indicators used in the strips. If this happens, instead of developing a purple color, the strip will very quickly turn to white. The best indicator of this effect is the presence of a thin blue line on the strip separating the wet portion from the dry portion of the strip.

How often should I test my bleach using 145 Chorine test paper?

Testing should be done at least once daily in smaller restaurants, and more frequently in busy establishments as each time the rinse solution is used, it will get slightly diluted.

What is the recommended ppm level of chlorine sanitizers in food establishments?

This depends upon your local health code. In many areas, the level is 50-100ppm available chlorine. It is best to check with your local health inspector for the level required in your area. Federal regulations (21 CFR Part 178) permit the use of hypochlorite solutions on food processing equipment and contact areas (tables) but state that solutions used for sanitizing equipment not exceed 200ppm available chlorine. If higher concentrations are used, a final rinse in potable water is required.

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