pH / ORP meter CP-250


The 250 series features a converter with built-in cleaning timer for practical use of functions without modification. A separate timer unit is unnecessary when used in combination with a cleaning unit thereby providing total cost-down operation.


  • Common pH / ORP meter
  • One-touch calibration simply by immersing the electrode in standard solution and pressing the CAL key
  • Electrode characteristic quality determined automatically
  • Compatible with 5 types of temperature compensation elements
  • Utilizes large customized LCD
  • Can be combined with cleaning device
  • Built-in cleaning unit control function

Manufactured by HORIBA Advanced Techno




Measuring system

pH: Glass electrode measurement method
ORP: Metal electrode measurement method

Measurement range

pH: 0.00 14.00
ORP: ± 2000 mV


pH ± 0.05
ORP ± 5 mV

Transmission output range

pH : 0.00 14.00 0.00 10.00 0.00 8.00 2.00 12.00 3.00 11.00 4.00 14.00 4.00 10.00 0.00 14.00 (Approved range)
*Note 1: ORP: ± 1400 mV ± 1000 mV ± 700 mV ± 350 mV - 1000 0 mV 0 1000 mV 2000 mV 0 700 mV (Changeable with internal DIG switch)

Contact output

Number of contacts: 3 Contact output for cleaning (CLN)
Contact form: Semiconductor (SSA) Relay, 1a
Contact capacity: A C200 V 1 A (Alternating current load)
Contact function: Electromagnetic drive for cleaning Warning contact output (RLY1)
Contact form: Relay contact, 1a (No-voltage contact) Contact capacity: AC 250 V 2 A (Resistance load)
Contact function: Upper limit warning, lower limit warning
Possible to select one function from above (Changeable with DIP switch) Warning contact output (RLY2)
Contact form: Relay contact, 1c (No-voltage contact)
Contact capacity: AC 250 V 3 A (Resistance load)
Contact form: Upper limit warning, lower limit warning, CLN synchronization (Synchronized with contact output for cleaning) Abnormal warning output
Possible to select one function from above (Changeable with DIP switch)

Contact input

Number of contacts: 1
Contact form: Relay contact, 1a (No-voltage contact) Contact function: External input for cleaning operation
Select one function from among the following;
(1) "OR" operation with internal cleaning timer (Operates together with external output)
(2) "AND" operation with internal cleaning timer (Operates only within external input range)
(3) Internal cleaning timer synchronized to external input
(4) Internal cleaning timer disabled
(5) External input disabled

Transmission output

DC 4 20 mA Input / output isolated, Maximum load resistance 600 Ω Linearity 0.5 % FS

Control operation

Proportional time sharing ON / OFF Control: Upper limit operation (H) and lower limit operation (L) (Changeable with internal DIP switch)
Upper / lower limit setting range: pH meter 0.00 14.00 pH
ORP meter ± 2000 mV
Control width: pH meter 0.01 4.00 pH (± 2.00 pH)
ORP meter 1 999 mV (± 499 mV)

Calibration function

pH meter 2-point automatic calibration or manual calibration (Changeable with DIP switch)
2-point automatic calibration: Automatic determination of standard solution type Potential stability automatically determined
Standard solution type pH 4, 7, and 9 (JIS)
Standard solution combination (pH 4, 7) (pH 7, 9)
Manual calibration: Standard solution type
Discretionary: 2 pH or higher difference ORP meter
Sensitivity calibration range 50.0 150.0 %

Additional function

Each error message type
1. Calibration error (Asymmetrical potential, sensitivity, response speed anomaly, standard solution anomaly)
2. Electrode diagnostic error Temperature sensor short, Temperature sensor tripped
3. Measurement out-of-range error Full scale over / under Alarm ON extension Extension time setting: 0 15 (minutes)
Cleaning timer settings
Cleaning cycle setting: 1 48 (hours)
Cleaning time setting: 0.1 20.0 (minutes)
Standby time after cleaning: 0.1 10.0 (minutes) Transmission output form setting when in hold due to calibration or cleaning Continuous, Hold (Previous value hold, Arbitrary hold) (Changeable with DIP switch)
Dumping factor (Response time depends on average number of movements)
Setting function
Setting time: 1 50 times (0 20 seconds) Fixed period nozzle cleaning operation setting For each prescribed time period, cleaning is conducted at short intervals to prevent dirt from sticking to the nozzle. (5-second interval for 1-hour cycle : Hold operation is disabled for this operation.) (Changeable with DIP switch)
Measured value shift function Setting range : pH: ± 2.00 pH ORP: ± 200 mV Transmission output hold arbitrary setting Setting range : Within measurement range

Temperature compensation element

500 Ω (25 °C) Other Compatible with 6.8 kΩ (25 °C), 350 Ω (25 °C), 1 kΩ (0 °C), or 10 kΩ (25 °C) (Changeable with internal DIG switch)

Temperature compensation range

0 100 °C) (For pH meter)

Ambient temperature & humidity

-5 50 °C, Less than 85 % RH


AC 100 115 V 50 / 60 Hz 7 VA or AC 200 240 V 50 / 60 Hz 7 VA (Depends on setting)


Outside equipment: JIS C0920 Protection class: 3 (Rain-proof type)
Installation procedure: 50 A pole or wall surface installation
Case: Aluminum alloy casting (Paint color: DIC G-262 or equivalent)
Full cover: Polycarbonate (Resin color: DIC G-262 or equivalent)
Hood: SUS304 (Paint color: DIC G-262 or equivalent, or DIC PART2 2600 or equivalent)
Mount fittings: SUS304

External dimensions

222 (W) x 180 (H) x 155 (D) (Mount fittings and protrusion not included)


Approx. 4 kg

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