Q45P/R pH/ORP Transmitter

Q45P/R pH/ORP transmitter is useful for monitoring requiring a 2-wire transmitter or battery-operated instrument. The Q45P/R transmitter provides durability, accuracy, and versatility for virtually any pH or ORP monitoring applications



Q45P/R pH/ORP Transmitter:

The Q45P/R pH/ORP Transmitter is the ideal choice for pH or ORP monitoring applications. The Q45 system provides the accuracy, versatility, and durability required for virtually any pH or ORP monitoring system. The transmitter is available in two types: pH or ORP, which can be selected when ordering.

The Q45P/R transmitters use differential type sensors designed for long life in demanding applications. Differential sensors are well-suited for applications that quickly poison conventional pH or ORP sensors, and are easily serviced. A variety of sensor styles is available to meet the need of almost any applications.

 There are 3 Power Options to choose from on Q45P/R Transmitter:

     -12-24 VDC, 2-Wire (single output only)

     -Portable Battery with two 0-2.5 V Outputs

     -External 5-17 VDC with two 0-2.5 V Outputs


Q45P/R Features:

     -Loop or Battery-Operated Power Options

     -Differential Sensors for long operating life

     -Submersion, In-Line, or Sanitary-Style Sensors

     -Clear Display -Large, easy-to-read LCD display.

     -Special High Purity sensor option

     -Adapts to Conventional pH or ORP sensors

     -Flexible Mounting - NEMA 4X (IP-66) enclosure is suitable for wall or pipe mounting.

Q45P/R pH/ORP Transmitter Specifications:

Sensor Type

pH: Series Q25P Differential or Conventional types

ORP: Series Q25R Differential or Conventional types

Display Range

pH: 0.00 - 14.00 ORP: -1000 to +2000 mv


0.02 pH or 2 mv


0.01 pH or 1 mv


0.01 pH or 1 mv

Analog Output

2-Wire unit: Single 4-20 mA DC, 450 ohms maximum

Battery unit: Two 0-2.5 VDC, 50K ohms minimum

External DC: Two 0-2.5 VDC, 50K ohms minimum

Power Requirements  

2-Wire unit: 17-30 VDC, 25 mA maximum

Battery unit: 2 AA Alkaline batteries

External DC: 5-17 VDC, 10 mA maximum

Output Isolation

600 V Galvanic isolation


NEMA 4X (IP-66) Polycarbonate, V-0 flammability


2-Wire of External DC Unit: 1lb. (0.45 Kg) 
Battery Unit: 2 lbs. (0.9 Kg)


CE marked to BS EN 61326-1:2006 Standard 
UL and CSA General Purpose


4.4”H x 4.4”W x 3.5”D (111 x 111 x 90 mm)

Mounting Options

Wall or pipe mounting bracket supplied

Conduit Entry

Two PG-9 cord grips, 0.16-0.31” diameter cable

Ambient Temperature

Operating: -40° to + 60°C 
Storage: -40° to + 70°C

Ambient Humidity

0-95%, Non-condensing


      -Auto-Clean systems are supplied with one package of pH 4 buffer and one package of pH 7 buffer for calibration, one o-ring kit, and 30 feet (or 60 feet) of air tubing.

      -For 115mm x 115mm panel mount, select Option 05-0068. For ½ DIN panel mount, select Option 07-0201.

      -Pipe mount requires two 2” U-bolts (47-0005).

Sensor Options:

Conventional Sensor

The most widely used pH sensors contain a hydrogen ion sensitive glass measuring electrode and a silver/silver chloride reference element. The reference element is sealed in the sensor which is filled with an electrolyte and electrically connected to the outside solution through porous junctions. The glass electrode is in direct contact with measured solution.

Conventional sensors are good for clean water applications and typically have an operating life of 1-3 years. They are relatively inexpensive and are available in submersible or inline versions.


Differential Sensor

Differential sensors have a pH sensitive glass electrode (identical to the measuring electrode) rather than the silver/silver chloride element of conventional sensors. The second glass electrode is housed in a chamber filled with pH 7 buffer. A high surface area junction connects the buffer system to the pH measuring element. The pH is then measured by calculating the voltage difference between the two glass electrodes.

Differential sensors are the best option for demanding applications like wastewater, plating baths, industrial process water, or high temperature applications. They are also good in applications containing sulfur as sulfur compounds destroy the silver/silver chloride component of conventional sensors. Differential sensors are much longer lasting.


ORP Calibration:

Product Range Price
ORP Calibration Kit
ORP Calibration Kit
Pocket Pro ORP Tester
Pocket Pro ORP Tester
±999 mV
ORP Calibration Kit

ORP Calibration Kit



View Details
Pocket Pro ORP Tester

Pocket Pro ORP Tester



±999 mV
View Details



Q45P/R pH/ORP Transmitter Brochure

Q45P pH Transmitter Typical Specs

Q45R ORP Transmitter Typical Specs




More Information
Manufacturer ATI
Call For Price Yes
Gas PH
4-20 mA Output Yes
Relays 2 Alarm Relays + 2 Control Relays
Voltage Output None
Power Requirements 12-24 VDC, Battery, external 5-17 VDC
Datalogging No
Warranty 1 Year
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