Hanna Instruments HI735 Total Hardness Low Range Checker

Introduction

Dear Customer, Thank you for choosing a Hanna Instruments product. This manual provides instructions for the Hanna Instruments HI735 Checker®HC handheld colorimeter. For more information, visit www.hannainst.com or contact Hanna Instruments.

Preliminary Examination

Upon receiving the Checker®HC, examine it carefully. If any issues arise, contact Hanna Instruments technical support. The HI735 is supplied with a case, reagent starter kit, cuvettes, syringes, pipettes, a battery, and this instruction manual. Retain all packing materials until the product is confirmed to be working correctly.

General Description & Intended Use

The HI735 Total Hardness Low Range handheld checker is designed to measure total hardness (as CaCO3) in various water types, including drinking water, process water, heating/cooling systems, swimming pools, and spas. It is also suitable for agricultural, food, and beverage applications. The device features simple, single-button operation, an easy-to-read LCD, and an auto shut-off function to conserve battery life.

Specifications

Functional Description & LCD Display

The checker comprises a cuvette holder, a liquid crystal display (LCD), and an ON/OFF button. The LCD displays measurement results and status messages.

Visual Description of Product Image: The Hanna Instruments HI735 Checker HC is shown. It is a compact, orange handheld device with a digital display showing "150" and "ppm Total Hardness LR".

Measurement Procedure

Follow these steps for accurate total hardness measurements:

1. Power On: Press the ON/OFF button. The display will show all segments, then "Add", "C.1" with "Press" blinking.
2. Prepare Cuvette for "C.1" (Zeroing):
   • Attach syringe tips, ensuring O-rings provide a seal.
   • Using a syringe, dispense 0.4 mL of unreacted sample into the cuvette (fill to the 0.6 mL mark). Clean excess liquid from the tip and push the plunger to the 1.0 mL mark.
   • Using a second syringe, dispense 0.6 mL of HI735IND-0 indicator into the same cuvette (fill to the 0.4 mL mark). Clean excess liquid and push the plunger to the 1.0 mL mark.
   • Use the supplied pipette to fill the cuvette to the 10 mL mark with HI735A-0 Reagent A, aligning the liquid's meniscus with the mark.
   • Add two drops of HI735B-0 Reagent B.
   • Screw on the cap, invert the cuvette 5 times to mix, ensuring no bubbles and a clean exterior.
   • Insert the cuvette into the checker and close the cap.
   • Press the ON/OFF button. The display will show "Add", "C.2" with "Press" blinking, indicating the checker is zeroed. Remove the cuvette.
3. Prepare Cuvette for "C.2" (Measurement):
   • Open one packet of HI735C-0 fixing reagent.
   • Unscrew the cuvette cap and add the contents of the HI735C-0 packet to the cuvette. Screw the cap back on.
   • Shake gently for 20 seconds until the reagent is dissolved and no bubbles are visible.
   • Insert the cuvette into the checker and close the cap.
4. Read Result: Press the ON/OFF button. The instrument will display the total hardness in ppm of CaCO3. The checker automatically turns off after 10 minutes of inactivity.

Water Hardness Guidelines

The following table provides general classifications for water hardness:

* 1 grain per gallon = 17.1 ppm. Note: Guidelines are based on U.S. Geological Survey (USGS) data and may vary by region.

Errors & Warnings

The checker displays messages for erroneous conditions or out-of-range values:

• Over Range: Blinking value indicates the measured value exceeds the method's limits. Verify sample clarity, dilute, and re-measure.
• Battery Low: Battery level is insufficient for proper operation. Replace the battery.
• Drained Battery: Battery is depleted. Replace with a new battery and restart.
• Light High: Excessive ambient light reaching the detector. Check zero cuvette preparation.
• Light Low: Insufficient light for measurement. Check zero cuvette preparation.
• Inverted Cuvettes: Sample and zero cuvettes are swapped. Swap them and repeat the measurement.
• Under Range: Blinking "0" indicates the sample absorbs less light than the reference. Check procedure and ensure consistent cuvette use for zeroing and measurement.

Battery Replacement

The checker automatically shuts down after 10 minutes of inactivity. A new battery supports approximately 5000 measurements.

To replace the battery:

1. Turn the checker off using the ON/OFF button.
2. Turn the instrument upside down, unfasten the screw with a screwdriver, and remove the battery cover.
3. Remove the old battery and insert a new 1.5V AAA battery, negative end first.
4. Replace the battery cover and tighten the screw.

Accessories

Reagent Sets:

• HI735-25: Reagents for 25 Total Hardness Low Range tests

Other Accessories:

• HI735-11: Total Hardness Low Range certified standard kit
• HI731225: Cuvette black cap for Checker® HC colorimeters (4 pcs.)
• HI731318: Cloth for wiping cuvettes (4 pcs.)
• HI731321: Glass cuvette and seal cap for Checker® HC colorimeters (4 pcs.)
• HI740028P: 1.5V AAA battery set (12 pcs.)
• HI740143: 1 mL graduated syringe (6 pcs.)
• HI740144P: Plastic pipette tip (10 pcs.)
• HI740157P: Plastic refilling pipette (20 pcs.)
• HI93703-50: Cuvette cleaning solution, 230 mL

Certification & Disposal

All Hanna Instruments products conform to CE European Directives. For electrical and electronic equipment disposal, do not treat as household waste; use appropriate recycling points to conserve resources. Dispose of batteries responsibly at designated collection points, not with household waste. Proper disposal prevents negative environmental and health consequences.

For more information, contact your local authorities or place of purchase.

Recommendations for Users

Ensure the checker is suitable for your specific application and environment. User modifications to the equipment may degrade performance. Do not use or store the checker in hazardous environments for safety.

Safety Measures

Reagent kit chemicals may be hazardous if handled improperly. Review Safety Data Sheets (SDS) at http://sds.hannainst.com before testing. For proper disposal of reagents and reacted samples, contact a licensed waste disposal provider.

Warranty

The HI735 Checker®HC is warranted for one year against defects in workmanship and materials, provided it is used and maintained according to instructions. The warranty covers repair or replacement free of charge. It does not cover damage from accidents, misuse, tampering, or lack of maintenance. For service, contact your local Hanna Instruments office. Provide model number, purchase date, serial number, and problem description. If repairs are not covered, you will be notified of charges. For returns, obtain a Returned Goods Authorization (RGA) number from Technical Service and ship prepaid with proper packaging.

Hanna Instruments reserves the right to modify product design without prior notice. All rights reserved.

Tips for Accurate Measurement

• Insert the cuvette in the same position for both C.1 and C.2 measurements.
• Ensure the sample is free of debris.
• Keep the cuvette dry and free of fingerprints or dirt before insertion.
• Wipe the cuvette thoroughly with the HI731318 microfiber cloth or a lint-free cloth.
• Swirl or gently tap the cuvette to remove bubbles that can cause higher readings.
• Do not let the reacted sample stand for extended periods after reagent addition, as it affects accuracy.
• Discard the sample immediately after reading to prevent permanent staining of the glass.