Well Bob Here is the specifications section of the Hanna Instruments TDS-1 Dissolved Solids Tester Meter with automatic temperature compensation. The specification section is typed letter for letter off the sheet inside the plastic storage case of my meter. Use this information how you see fit. ---------------------------------------------------------------------------------
SPECIFICATIONS Range 0 to 999 ppm (mg/L) Resolution 1 ppm Accuracy (@20C/68F) +-10ppm Typical EMC Deviation +- 1% F.S. Calibration Solution Hi 70080P (optional) Temperature Compensation Automatic from 5 to 50C (41 to 122F) Environment 0 to 50C (32 to 122F) 95RH Batteries Life 4 X 1.4V alkaline approx. 150 hours Dimensions 150 X 30 X 24 mm (5.9 X 12. X 0.9") Weight 85 G (3 oz.) ACCESSORIES HI 76504/P4 1.4 V battery (4 pcs) HI 70080P 800ppm (mg/L) TDS sachets (25 X 20 mL) HI 731326 Calibration screwdriver (20pcs) ---------------------------------------------------------------------------------------- For your information this is the calibration document that Hanna included when I received my meter ------------------------------------------------------------------------------------------. Calibration: 704 ppm Test Value: 811 ppm Reading: 782 Test Value: 294 ppm Reading: 289 Operator: ID. 7.21 Date: 7/02/00 ------------------------------------------------------------------------------------------ Check the Hanna web site for the TDS-1 http://www.hannainst.com/products/tdspromo.htm "Excellent Accuracy + 2% Full Scale" 2% at full scale is (.02 X 999 = 19.98) or to round it off 20 ppm When test equipment error is listed at full scale the error exists across the entire scale so the 20 ppm of error exists at 0 ppm and also at 999 ppm. Back to what I said originally, for $14.90 this is a good meter for testing 250 ppm or greater. Tai-Pan wrote: > Hi Brad, > > Where did you get this ***from. You have not described a TDS-1. For > sure you don't know how it works. Try reading the spec sheet. :-) > Then take one apart and make the circuit diagram. Then put some good > test equipment on it and see what it does. :-) > > Bless you Bob Lee > > > > Brad Kirby wrote: > >> The Hanna TDS-1 has a accuracy of +- 10 ppm (@ 20 deg C. or 68 deg >> F) . >> When calibrated with the 800 ppm packets, your readings have a range >> of 20 ppm. Your distilled water that measures 0 ppm with this meter >> could actually have 10 ppm of Total Dissolved Solids. Also a CS >> solution that is actually 10 ppm may have a meter reading range from >> 0 to 20 ppm ( 100% error). The TDS-1 was designed to measure ppm in >> the range 200 ppm ( 5% error) or higher. Both the TDS-1 and the PWT >> are conductive meters. They function electrically identical by >> passing a current between two electrodes and performing temperature, >> range and calibration factors built into each unit. I own a TDS-1. > > -- > oozing on the muggy shore of the gulf coast > [email protected] >
