HACH - Formula for water analysis.
SensION156 Portable pH/ Dissolved Oxygen Meter, with Platinum pH Electrode & DO Probe

Hach sensION156 Meter provides multi-parameter confidence in one single instrument:

•  Measures pH, Dissolved Oxygen, Conductivity, TDS, Salinity and Temperature
• Includes Platinum pH electrode and Dissolved Oxygen-DO probe
• Slip-resistant keypad for resistance to muddy hands, yet easy to clean
•  Anti-glare coating for easy viewing
•  Backlit screen for easy night-time sampling
•  1, 2 or 3 point quick pH calibration procedure
•  Resolution to 0.1, 0.01, 0.001; for the right accuracy when you need it
• All-in-one 5-pin connector for easy determination of temperature and your chosen parameter
• Measures/ compensates temperature in ° C or ° F
•  Built-in barometer for DO samples
• Automatic buffer recognition with 4.01, 6.86, 7.00 and 10.01 buffers
•  Floatable and Watertight IP67-rated seal
• User-activated calibration review, time and date stamps for GLP
•  Many color-coded buffers to choose from
• Download data easily with docking station
• Can calibrate with either NaCl or KCl
• Autocorrects for altitude, barometric pressure, and salinity
  

Specifications
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Range:
pH: - 2.00 to 19.999
ORP: ± 2000 mV
mV: ± 2000 mV
Conductivity: 0 to 199.9 µ S/ cm;
200 to 19, 999 µ S/ cm; 2 to 199.9 mS/ cm;
20 to 199.9 mS/ cm.
TDS: 0 to 50, 000 mg/ L as NaCl
Salinity: 0 to 42 g/ L ( ppt)
Dissolved Oxygen: 0 to 20.0 mg/ L;
0.1% saturation
Temperature: pH/ Cond. Tests:
-10 to 110 ° C
DO Test: 0 to 50 ° C
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Resolution:
pH: 0.1/ 0.01/ 0.001 ( selectable)
ORP: 0.1 mV
mV: 0.1 mV
Conductivity: 0.1 µ S; 1 µ S;
0.01 mS; 0.1 mS
TDS: 3 significant digits
Salinity: 0.1 g/ L ( ppt)
Dissolved Oxygen: 0.01 or 0.1 mg/ L; 0.1% saturation
Temperature: pH/ DO Tests: 0.1 ° C
Cond. Test: ± 0.1 ° C
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Accuracy:
pH: ± 0.002
ORP: ± 0.2 mV or ± 0.1% of reading, whichever is greater.
mV: ± 0.2 mV or ± 0.1% of reading, whichever is greater.
Conductivity: ± 0.5% in first 3 ranges; 1.0% at highest range
TDS: ± 0.5% of full scale
Salinity: ± 0.1 ppt ( -2 to 35 ° C)
Dissolved Oxygen: ± 1% full scale
Temperature: ± 0.3 ° C at 0 - 70 ° C;
± 1.0 ° C at 70 - 110 ° C
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Outputs:
One-way, RS-232 via docking station/ 199-point memory recall
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Inputs:
( 2) 5-pin connector
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Power Requirements:
4 AA batteries or 110 to 220 VAC line power through docking station.
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Input Impedance:
> 1012 Ohms
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Buffer Recognition:
Auto; 4.01, 6.86, 7.00, 10.01
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Display:
Custom LCD with Backlight
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Calibration Points:
pH Test: 3-point calibration
Cond.Test: 1 is standard. Mode directly adjusts to cell constant.
DO Test: Single point
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Calibration Review:
User-activated; shows last cal scope, date, standards used, temperature, buffers/ standards, and mV.
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Serial Data Output:
RS-232 via docking station
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Battery Life:
6 months typical use ( 500 hours continuous)
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Low Battery Indicator:
Yes
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Waterproof:
Yes, IP67
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Dimensions:
21.2 x 8.7 x 4.2 cm ( 8.35 x 3.43 x 1.65" )