TDS Calibration Solutions by HM DIGITAL

For use with the HM Digital TDS-EZ, TDS3 & TDS4 Testers
or any TDS tester that requires an NaCl calibration solution

For optimal performance, re-calibrate your meters periodically or if testing TDS or conductivity levels in wide or different ranges.

FEATURES

• NaCl calibration solution, available in 342 ppm or 1000 ppm.
• Comes in lightweight HDPE plastic bottles.
• Sealed with a coated foam liner.

SPECIFICATIONS

• NaCl solution
• Available in 342 ppm or 1000 ppm
• 3 oz. bottles (88.7 ml)

Solution Conversions
 
342 NaCl = 
362 as KCl ; 478 as "442" ; 700 µS 

1000 NaCl = 
1060 as KCl ; 1450 as "442" ; 2000 µS

Calibration Instructions for HM Digital TDS-EZ, TDS3 & TDS4 Testers

• HM Digital meters are factory calibrated at 342ppm NaCL and are designed to stay consistent. - However, you may need to recalibrate your meter from time to time or for certain applications. TDS meters are most accurate when calibrated as close as possible to the sample being tested. For best results, calibrate at 25 oC (77 oF)

• To insure accuracy and consistency, recalibrate your meter using a commercial standard solution. This can be done prior to usage and should be done after prolonged usage.

• For drinking water we recommend calibrating in a range of 90ppm to 700ppm.

• Make sure your meter is clean and dry before placing it in the bottle of calibration solution so you do not contaminate the solution.

Step 1: Turn the meter on, insert the meter into the calibration solution and read the TDS level of the solution.

Step 2: If the meter does not read within 2% of the solution, adjust the reading by inserting a mini screwdriver into the trimmer pot (small hole on the rear of the meter). Gently turn the trimmer screw clockwise to increase the reading and counterclockwise to decrease the reading.
  - Make sure the screwdriver fits evenly into the groove of the screw.
  - Note that the trimmer pot is very sensitive! Remove the screwdriver carefully.
  - Try to keep the meter vertical.

Step 3: Once the meter reads within 2% of the solution, gently release pressure on the screwdriver and remove from the trimmer pot.
  - If the screwdriver is retracted abruptly, the reading may jump.

Step 4: With the meter in the solution and the reading at the correct level, press the "HOLD" button. Let the reading hold for approximately 10 seconds to fully stabilize.

Step 5: Remove the meter from the solution. Shake the meter to remove any water drops that may adhere to the probes and casing, creating air gaps.
  - Water droplets or air gaps may cause the meter to display an incorrect reading.

Step 6: Turn the meter off, wait a moment and turn the meter on again.

Step 7: Insert the meter into the calibration solution and verify the reading. If the reading is accurate, calibration is complete. If not, repeat the procedure.