Solutions required for Model U/W-20 Series and

Model U-10 Manual Calibrations


PH Calibration Solutions

PH 7 Buffer Part Number 9003001700 Actual Value 6.86

PH 4 Buffer Part Number 9003001600 Actual Value 4.01


ORP Calibration Check Solutions (not a standard)

Model number: 160-51 Part number: 9003003100 89mV @ 25ºC

Model number: 160-22 Part number: 9003003000 258mV @ 25ºC


Conductivity Calibration Solutions; zero calibration in air

1 mS/m = 0.001 S/m = 10 mhos/cm 1 mho/cm = 0.1 mS/m

0.005 mol/L Solution: Weigh 0.373 grams of potassium chloride (dried for 2 hours at 105C), dissolve in a 1 liter volumetric flask to the fill line.

(Range 3 ; 0.0 to 99.9 mS/m) 71.8 mS/m; 717.5 mho/cm; 718 µS/cm; 0.718 mS/cm


0.05 mol/L Solution: Weigh 3.73 grams of potassium chloride (dried for 2 hours at 105C), dissolve in a 1 liter volumetric flask to the fill line.

(Range 2 ; 0.090 to 0.999 S/m)) 0.667 S/m; 6667 mho/cm; 6667 µS/cm; 6.67 mS/cm


0.5 mol/L Solution: Weigh 37.2 grams of potassium chloride (dried for 2 hours at 105C), dissolve in a 1 liter volumetric flask to the fill line.

(Range 1 ; 0.90 to 9.99 S/m) 5.87 S/m ; 58700 mho/cm; 58700 µS/cm; 58.7 mS/cm


Turbidity Calibration Solutions

Zero Calibration: Use distilled or deionized water


Span Calibration: Pipet 100ml of 4000 NTU Stock solution into a 500 ml volumetric flask. Fill the 500 ml volumetric to the fill line


4000 NTU Stock Solution: Weigh 5.0g of hydrazine sulfate and dissolve it in 400ml distilled water. Weigh 50g of hexamethylene tetramine in 400ml distilled water. Combine both solutions in a 1000ml volumetric flask and fill with distilled water to the fill line. Allow to stand 48 hours before preparing the 800 NTU solution.


Dissolved Oxygen Calibrations

Zero Calibration: Weigh 50g of Sodium Sulfite. Dissolve in a 1000ml volumetric flask with deionized water or tap water and fill to the fill line.


Span Calibration: In air is possible however recommended method is oxygen saturated water.


Calibrations: check temperature measurement first

  1. Conductivity: calibrate units with 3 standards; 71.8 mS/m, 0.667 S/m, 5.87 S/m

  2. pH: 6.86 buffer, span with 4 buffer

  3. Turbidity: Zero with water, Span with 800 NTU standard

  4. Dissolved Oxygen: Zero with DO zero solution, span with air or oxygen saturated water.

  5. Depth: in pressure tester at 98 kPa; (kPa to PSI x 0.145038) (PSI to kPa x 6.895)