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Home>Water Filter Brands>HM Digital Testing Products > HM-DIGITAL-DM-1


HM Digital DM-1 In-Line Dual TDS Monitor for In / Out Water Lines

3" x 0.8" x 1.9"; 0-9990 ppm

HM Digital In-Line Dual TDS Meter DM-1 meters total dissolved solids for incoming and outgoing water
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Product Code: HM-DIGITAL-DM-1
Retail Price: $42.00
  • HM Digital In-Line Dual TDS Monitor DM-1:
  • The DM-1 helps you to measure the tap water coming in vs. the purified water going out of your water filtration system at any time.
  • The In-Line Dual TDS Meter displays TDS levels of the feed water and product water with in & out electrode probes.
  • This TDS Monitor is highly efficient and accurate due to its advanced microprocessor technology.
  • The Dual TDS Monitor has an auto-off function that conserves battery power. The unit shuts off automatically after 10 minutes of non-use.
  • Dual Range: 0-9990 ppm (From 0 - 999 ppm the resolution is 1 ppm. From 1000 to 9990 ppm, the resolution is 10 ppm, indicated by a blinking 'x10' image.).
  • The DM-1 TDS monitor is factory calibrated with a 342 ppm NaCl solution and can be recalibrated with a mini-screwdriver.
  • The DM-1 monitor comes equipped with Mur-lok Quick-Connect T-fittings.
  • The DM1 Dual Total Dissolved Solids Monitor installs quickly and easily .
  • HM Digital DM-1 In-Line Total Dissolved Solids Meter with Advanced Micro-processors Specs:
  • Range: 0-9990 ppm.
  • Accuracy: 2%.
  • Conversion Factor: NaCl (avg. 0.5).
  • Cable Length: 24.5" (including sensor).
  • Fittings: Standard 1/4", also available with 3/8" or 1/2".
  • Power Source: 2 x 1.5V button cell batteries (included).
  • Battery Life: Approximately 1000 hours of continuous use.
  • Size: 3" x 0.8" x 1.9" (7.6 x 2 x 4.7 cm).
  • Weight: 2.8 oz (79.4 g).
  • Manufacturer: HM Digital DM-1
  • HM Digital DM-1 Dual In-Line TDS Meter:
  • The battery has to be replaced after around 1000 hours of use.
  • HM Digital DM-1 In-Line TDS Meter Instructions:
  • The DM-1 is designed to be used with flowing water. Due to nature of mobile charged ions in electrical conductivity and flowing water, it is normal to experience discrepancies and fluctuations within 2% of the readings.
  • Make sure the sensor is properly inserted into the fitting.
  • Make sure to align the dot on the sensor with the dot on the fitting. If there is no dot on the fitting (this may happen if you received a non-standard fitting or replaced the fitting), then align the metal probes parallel to the direction of the fitting (once the sensor has been inserted into the fitting, look through it you should only see one metal probe).
  • Always wait 10-20 seconds for more accurate readings.
  • Rinse in de-ionized water or alcohol after prolonged use to ensure proper readings.
  • The base of the DM-1 is not waterproof.
  • Do not store unit in high temperature or direct sunlight.

  • Calibration
  • HM Digital monitors are factory-calibrated at 342ppm NaCl and 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 to be tested. For best results, calibrate at 25 °C (77 °f).
  • To ensure 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, it is recommended to calibrate in a range of 90 ppm to 700 ppm.
  • For the DM-1, calibration is done for both sensors simultaneously.
  • You will need the following:
  • Calibration solution.
  • A tube/hose that is the same size as the fittings.
  • A bucket or basin.
  • A pump.

  • Step 1: Attach the IN and OUT sensors to the tubing that you will use for the calibration. It will be necessary to cut the tube in two places so that the same solution will be running through both sensors and so that the sensors are not too far apart from each other.
  • Step 2: Configure the tube within a bucket or basin, using a pump so that the calibration solution will be cycled through the tube. In other words, the calibration solution needs to be flowing over both sensors to calibrate properly.
  • Step 3: Once everything is set-up, turn on the unit and measure the calibration solution. If the monitor does not read within 2% of the solution (on either the in or out), adjust the reading by inserting a mini screwdriver into the trimmer pot (small hole on the rear of the monitor). Gently turnthe trimmer clockwise to increase the reading and counterclockwise to decrease the reading.
    • It does not matter if IN or OUT is selected. Both sensors are calibrated simultaneously and calibrating one side will automatically calibrate for the other side.
    • Make sure the screwdriver fits evenly into the groove of the screw.
    • Note that the trimmer pot is very sensitive! Remove the screwdriver carefully.
  • Step 4: 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 5: Turn the monitor off and on. Verify the readings for both sensors. If the readings are accurate with 2%, calibration is complete. If not, repeat the procedure.
  • HM Digital DM-1 Manual
    (Download Adobe Reader).

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