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Sato SK-650PH Desktop Digital pH Meter
Sato SK-650PH desktop digital pH meter for laboratory, industrial and general liquid pH measurement. Select the appropriate probe according to the sample and application.
- Display: pH, temperature and mV.
- Calibration: Up to 3 points.
- Memory: Up to 99 readings.
- Probe: PHP-31 or optional 640S Series sold separately.
Sato SK-650PH Desktop Digital pH Meter
The Sato SK-650PH is a desktop digital pH meter for laboratory, industrial and general liquid measurement.
The meter displays pH together with temperature and provides functions for sensor-condition checking, calibration, data storage and computer connection. A sensor arm is supplied for positioning the electrode during measurement and for use together with a laboratory stirrer.
The SK-650PH is supplied without a pH probe. Select the probe according to the sample, measuring range and required electrode construction.
Key Functions
- pH, temperature and mV display
- Sensor sensitivity indication for checking electrode condition
- Stability indication when the measured value has settled
- Automatic temperature compensation with compatible probes
- Date and time display together with measurement
- One-, two- or three-point pH calibration
- 99-reading data memory
- RS-232C data output
- Sensor arm supplied as standard
- Multiple pH probe options for different applications
Calibration Points
The SK-650PH supports calibration using up to three points selected from the following standard solutions at 25°C.
| Calibration Point | Standard Solution |
|---|---|
| pH 4.01 | Phthalate standard solution |
| pH 6.86 | Neutral phosphate standard solution |
| pH 9.18 | Borate standard solution |
| pH 10.01 | Carbonate standard solution |
SK-650PH Specifications
| Specification | Details |
|---|---|
| Cat. No. | 6427-00 |
| Model | SK-650PH |
| pH Display Range | 0.00 to 14.00 pH |
| Temperature Display Range | -6.0°C to 82.0°C |
| mV Display Range | -2002 to +2002 mV |
| pH Resolution | 0.01 pH |
| Temperature Resolution | 0.1°C |
| mV Resolution | 0.1 mV from -199.9 to +199.9 mV; 1 mV outside this range |
| pH Repeatability | ±(0.01 + 1 digit) pH |
| Temperature Repeatability | ±(0.1 + 1 digit)°C |
| Sampling Time | Approx. 1 second |
| Data Memory | Up to 99 readings |
| Output | RS-232C |
| Operating Environment | 5°C to 40°C, below 95%RH, non-condensing |
| Storage Environment | -10°C to 50°C, non-condensing |
| Power | Dedicated 9 VDC AC adapter |
| Material | ABS resin body and sensor arm |
| Dimensions | 215 (W) × 58 (H) × 170 (D) mm, excluding sensor arm |
| Weight | Approx. 915 g, excluding sensor arm |
| Standard Accessories | Sensor arm, AC adapter and instruction manual |
Probe Selection
The measuring range and accuracy of the complete SK-650PH system depend on the probe connected to the meter.
Sato provides a standard PHP-31 probe together with the 640S Series for general-purpose, immersion, high-alkali, flat-surface, test-tube and small-sample applications.
PHP-31 Standard Probe
The PHP-31 is the standard combination pH and temperature probe for general liquid measurements.
| Specification | pH | Temperature |
|---|---|---|
| Cat. No. | 6400-30 | |
| Model | PHP-31 | |
| Measuring Range | 0.00 to 14.00 pH | 0.0°C to 50.0°C |
| Accuracy | ±0.28 pH from pH 0 to 2 ±0.08 pH from pH 2 to 12 ±0.38 pH from pH 12 to 14 |
±0.3°C from 20°C to 30°C ±0.5°C outside this range |
| Sensor | Lead-free glass electrode | Thermistor |
| Internal Solution | Non-refillable KCl solution | |
| Probe Size | Ø12 × 135 mm | |
| Cable | Approx. 1 m | |
| Weight | Approx. 76 g | |
640S Series Optional pH Probes
Select the 640S probe according to the physical form and chemical condition of the sample.
| Cat. No. | Model | Application | pH Range | Temperature |
|---|---|---|---|---|
| 6424-00 | 640S-1 | General purpose | 2.00 to 13.00 | 0 to 50°C |
| 6425-00 | 640S-2 | Immersion / waterproof | 2.00 to 13.00 | 0 to 50°C |
| 6425-10 | 640S-3 | High-alkali measurement | 2.00 to 14.00 | 0 to 50°C |
| 6425-20 | 640S-4 | Flat-surface measurement | 2.00 to 13.00 | No built-in temperature sensor |
| 6425-30 | 640S-5 | Test tubes | 2.00 to 13.00 | No built-in temperature sensor |
| 6425-40 | 640S-6 | Minute / very small samples | 2.00 to 13.00 | No built-in temperature sensor |
640S-1 General-Purpose Probe
The 640S-1 is intended for general liquid pH measurement. It contains both a pH electrode and temperature sensor, allowing automatic temperature compensation when connected to the SK-650PH.
| pH Range | 2.00 to 13.00 |
|---|---|
| Temperature Range | 0 to 50°C |
| pH Accuracy | ±0.03 pH |
| Temperature Accuracy | ±0.5°C |
| Liquid Junction | Sleeve type |
| Internal Solution | 3.3 mol/L KCl, refillable |
| Probe Size | Ø12 × 156 mm |
| Cable | 1 m standard; optional longer lengths available |
640S-2 Immersion Probe
The 640S-2 has a waterproof probe construction and can be immersed in tanks or other suitable liquid samples.
| pH Range | 2.00 to 13.00 |
|---|---|
| Temperature Range | 0 to 50°C |
| pH Accuracy | ±0.03 pH |
| Temperature Accuracy | ±0.5°C |
| Liquid Junction | Ceramic type |
| Internal Solution | 3.3 mol/L KCl, non-refillable |
| Probe Size | Approx. Ø34 × 147 mm |
| Cable | 3 m standard; optional longer lengths available |
640S-3 High-Alkali Probe
The 640S-3 extends the pH range to 14.00 and is intended for suitable high-alkali liquid measurements.
| pH Range | 2.00 to 14.00 |
|---|---|
| Temperature Range | 0 to 50°C |
| pH Accuracy | ±0.03 pH |
| Temperature Accuracy | ±0.5°C |
| Liquid Junction | Sleeve type |
| Internal Solution | 3.3 mol/L KCl, refillable |
| Probe Size | Ø12 × 159 mm |
640S-4 Flat-Surface Probe
The 640S-4 is designed for pH measurement of suitable flat surfaces such as leaves, skins and cut fruit surfaces.
| pH Range | 2.00 to 13.00 |
|---|---|
| pH Accuracy | ±0.03 pH |
| Operating Temperature | 15 to 50°C |
| Temperature Compensation | No built-in temperature sensor |
| Liquid Junction | Sleeve type |
| Internal Solution | 3.3 mol/L KCl, refillable |
640S-5 Test-Tube Probe
The 640S-5 has a slender measuring section for insertion into test tubes and other narrow sample containers.
| pH Range | 2.00 to 13.00 |
|---|---|
| pH Accuracy | ±0.03 pH |
| Operating Temperature | 10 to 50°C |
| Temperature Compensation | No built-in temperature sensor |
| Measuring Section | Ø6 × 190 mm |
| Overall Probe Length | Approx. 270 mm |
640S-6 Minute-Amount Probe
The 640S-6 is designed for very small samples such as a small droplet where a conventional pH electrode is too large.
| pH Range | 2.00 to 13.00 |
|---|---|
| pH Accuracy | ±0.03 pH |
| Operating Temperature | 10 to 50°C |
| Temperature Compensation | No built-in temperature sensor |
| Measuring Section | Ø3 × 50 mm |
| Overall Probe Length | Approx. 148 mm |
Probe Selection by Application
| Measurement Requirement | Probe |
|---|---|
| Standard general liquid measurement | PHP-31 or 640S-1 |
| Probe immersed into a tank | 640S-2 |
| Higher-alkalinity samples | 640S-3 |
| Flat or cut surface | 640S-4 |
| Narrow test tube | 640S-5 |
| Very small sample volume | 640S-6 |
Automatic Temperature Compensation
Automatic temperature compensation is available when the connected probe contains a compatible temperature sensor.
PHP-31, 640S-1, 640S-2 and 640S-3 provide temperature measurement together with pH measurement.
The 640S-4, 640S-5 and 640S-6 do not contain a temperature sensor, so automatic temperature compensation is not available from those probes alone.
Sensor Sensitivity Display
The SK-650PH includes a sensor sensitivity display that helps indicate the condition of the connected pH electrode.
This can be used as a guide when deciding whether electrode cleaning, maintenance or replacement may be required.
Data Memory and PC Output
Up to 99 readings can be stored in the meter for later review. Stored pH data include the data number, pH value, temperature and time.
The SK-650PH also provides RS-232C output. An optional RS-232C cable is required for connection to a computer.
Standard Solutions
| Cat. No. | Standard Solution |
|---|---|
| 6401-10 | pH 4.01 phthalate solution, 500 mL |
| 6402-10 | pH 6.86 neutral phosphate solution, 500 mL |
| 6404-10 | pH 9.18 borate solution, 500 mL |
| 6403-10 | pH 10.01 carbonate solution, 500 mL |
Typical Applications
- Laboratory pH measurement
- General liquid testing
- Industrial sample testing
- Research and development
- Water and solution checks
- Quality-control laboratories
- Tank measurements with immersion probe
- Flat-surface pH measurements
- Small-volume samples
- Test-tube measurements
Before Selecting a Probe
Confirm the following:
- Expected pH range
- Sample type and chemical compatibility
- Liquid, surface or very small sample measurement
- Need for automatic temperature compensation
- Required immersion depth
- Required cable length
- Whether the sample requires a specialised electrode
The SK-650PH meter itself has a display range of 0.00 to 14.00 pH, but the actual measuring range and accuracy depend on the connected probe.
Calibration Note
Sato lists calibration service as available for the SK-650PH. JCSS-accredited calibration is not available for this model. Suitability for regulated, certification or transaction applications should therefore be confirmed according to the user's measurement requirements.
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