1. Introduction
The HACH Total Hardness Test Kit, Model 5-B, provides a simple and economical method for determining water hardness through drop count titration. This kit is designed for field and laboratory use, offering reliable measurements of total hardness expressed as CaCO₃. The method utilizes a drop count titration with a range of 1-30 grains per gallon (gpg), with each drop of titrant equivalent to 1 gpg. The kit contains sufficient reagents for approximately 100 tests.
2. Safety Information
WARNING: This kit contains chemicals that may be harmful if misused. Carefully read the label on each container before use.
- Always wear appropriate personal protective equipment, such as safety glasses, to protect eyes from chemical splashes.
- Avoid direct contact of reagents with skin and clothing. In case of contact, rinse immediately with plenty of water.
- Do not ingest any reagents. If ingested, seek immediate medical attention.
- Wash hands thoroughly with soap and water after handling chemicals.
- Dispose of all chemical waste according to local environmental regulations.
3. Kit Components
The HACH Total Hardness Test Kit, Model 5-B, includes the following items:
- Titrant Solution, Hardness 3, 0.015 M EDTA (100 mL bottle with dropper)
- UniVer® 3 Hardness Reagent (powder, 26.3 g bottle)
- Measuring Tube (Cat. No. 438-00)
- Square Mixing Bottle (Cat. No. 439-06)
- Measuring Scoop (for UniVer® 3 Hardness Reagent)
4. Setup
Before beginning the test, ensure all components are clean and readily accessible. Work in a well-lit area.
- Unpack all kit components and verify their presence against the list above.
- Rinse the measuring tube and square mixing bottle thoroughly with the water sample to be tested, then discard the rinse water. This prevents contamination from previous tests or tap water.
5. Operating Instructions: Drop Count Titration
Follow these steps to perform a total hardness test:
- Collect Sample: Fill the measuring tube (Cat. No. 438-00) to the 25 mL mark with the water sample to be tested.
- Transfer Sample: Pour the 25 mL water sample from the measuring tube into the square mixing bottle (Cat. No. 439-06).
- Add Reagent: Using the provided measuring scoop, add one level scoop of UniVer® 3 Hardness Reagent (Cat. No. 511-00) to the square mixing bottle. Cap the bottle and swirl gently to mix until the powder dissolves completely. The sample should turn a red or pink color if hardness is present. If the sample turns blue immediately, the water is very soft (less than 1 gpg).
- Titrate Sample: Hold the Titrant Solution bottle (0.015 M EDTA) vertically and add the solution drop by drop to the sample in the square mixing bottle. After each drop, cap the bottle and swirl to mix thoroughly.
- Observe Color Change: Continue adding drops and swirling until the color of the sample changes from red/pink to a clear blue. This is the endpoint of the titration.
- Count Drops: Record the total number of drops of Titrant Solution added to achieve the color change.
Calculation: Each drop of Titrant Solution corresponds to 1 grain per gallon (gpg) of total hardness. Therefore, the number of drops equals the total hardness of your water sample in gpg.
Conversion: To convert grains per gallon (gpg) to milligrams per liter (mg/L) as CaCO₃, multiply the gpg value by 17.1. (1 gpg = 17.1 mg/L CaCO₃).
6. Interpreting Results
The total number of drops of Titrant Solution required to change the sample color from red/pink to blue directly indicates the water hardness in grains per gallon (gpg). For example, if 10 drops were required, the water hardness is 10 gpg.
Understanding your water hardness is crucial for various applications, including water treatment, appliance maintenance, and industrial processes.
7. Maintenance
Proper maintenance ensures the longevity and accuracy of your test kit.
- Cleaning: After each use, thoroughly rinse the measuring tube, square mixing bottle, and scoop with distilled or deionized water. Allow them to air dry completely before storage.
- Storage: Store all reagents in their original containers, tightly capped, in a cool, dark place away from direct sunlight and extreme temperatures. Ensure the Titrant Solution bottle is stored upright.
- Reagent Expiration: Check the expiration dates on the reagent bottles. Expired reagents may lead to inaccurate results. Replace reagents as needed.
8. Troubleshooting
If you encounter issues during testing, consider the following common problems and solutions:
- No Color Change to Red/Pink: If the sample does not turn red/pink after adding UniVer® 3 Hardness Reagent, the water may be extremely soft (less than 1 gpg) or the reagent may be expired. Try a known hard water sample to verify reagent activity.
- Inaccurate Results:
- Ensure all glassware is clean and free from contamination.
- Verify that reagents are not expired.
- Ensure accurate measurement of the water sample (25 mL).
- Add titrant drops consistently and swirl thoroughly after each drop.
- Difficulty Seeing Color Change: Perform the test under good lighting conditions. A white background can help make the color change more apparent.
9. Specifications
| Specification | Detail |
|---|---|
| Model Number | 145300 |
| Parameter | Hardness, Total - As CaCO₃ |
| Method Name | Drop Count Titration / EDTA-bulk powder |
| Range | 1-30 gpg (grains per gallon) |
| Approximate Tests | 100 |
| Package Dimensions | 5.04 x 2.68 x 2.6 inches |
| Item Weight | 8.96 ounces |
| Manufacturer | HACH COMPANY |
10. Warranty and Support
HACH products are manufactured to high-quality standards. For specific warranty information, please refer to the documentation included with your purchase or visit the official HACH website. For technical support, product inquiries, or to purchase replacement reagents, please contact HACH customer service or visit the HACH store online.
HACH Store: https://www.amazon.com/stores/Hach/page/F31EE231-E533-4E96-B7EB-49EC9C17D676
