The HM Digital DM-2 reads feed water against product water on demand, so an operator can judge an RO or filtration system's rejection rate at a glance. Two permanently installed ¼" sensors sit in the line; a switch selects IN or OUT.
Commercial build: water-resistant casing, long shielded cables, oversized LCD, variable mounting bracket, and independent digital calibration on each line. Dual-range to 9990 ppm with an ‘x10’ multiplier above 999 ppm.
| SKU / Model | DM-2 |
| Product Type | In-line dual (feed vs. product) TDS monitor, commercial grade |
| TDS Range | 0–9990 ppm, dual range |
| Resolution | 0–999: 1 ppm · 1000–9990: 10 ppm (blinking ‘x10’ icon) |
| Accuracy | ±2% of reading |
| Conversion Factor | NaCl (avg. 0.5) |
| Factory Calibration | 342 ppm NaCl (digital) — IN and OUT sensors calibrate separately |
| Sensors | Dual, ¼" diameter for quick-connect fittings |
| Sensor Cable Length | 46" (116.8 cm) including sensor, shielded |
| Power Source | 2 × AA batteries |
| Low-Battery Indicator | ‘bat’ shown for 3 seconds at power-on |
| Auto Shut-Off | After 3 minutes |
| Dimensions | 4.6 × 2.6 × 0.7 in (11.6 × 6.8 × 1.8 cm) |
| Weight | 7.9 oz (224.3 g) including batteries |
| Warranty | 1 Year Limited Warranty |
Specifications transcribed from the HM Digital DM-2 User’s Guide.
📖 DM-2 Manual (PDF)Installation, calibration, battery replacement and troubleshooting. Published by HM Digital, Inc.
