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Q45P/R pH/ORP Monitor


Sealed Reference System, for Longer Sensor Life!

Measurement and control of pH is important in a wide variety of industries. Water and wastewater, boiler feed water, high purity water, food processing wash water, chemical plant cooling water, and many other aqueous systems require reliable pH monitoring. ATI’s Model Q45P pH water quality monitor provides the combination of durability, accuracy, and versatility required for virtually any pH monitoring or control application. The Model Q45R provides the same reliable monitoring for Oxidation- Reduction Potential (ORP) applications.
A Blast of Air Keeps the Auto-Clean Sensor Clean!
ATI provides the ideal answer for automatic pH or ORP sensor cleaning. Employing a unique “air-blast” cleaning method, sensors can be cleaned as often as necessary without operator attention. Pulses of pressurized air delivered through a nozzle at the tip of the sensor remove accumulated solids from critical sensing surfaces, resulting in accurate and reliable measurements.


There is no single pH sensor that fits every application. Sensors designed for harsh environments do not necessarily work as well in high purity water. Understanding the difference between various sensor types will help you choose the best sensor for your application.
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 inside the sensor body filled with an electrolyte and electrically connected to the outside solution through one or more porous reference junctions. The glass electrode is in direct contact with the measured solution.
      Submersible Sensor    
        Twist-Lock Sensors    
     Sealed Acrylic Flowcell  
Conventional sensors are a good alternative for clean water applications with conductivity above about 50 microsiemens (μS). They typically provide an operating life of 1-3 years depending on the application and are relatively inexpensive. They are available in submersible or in-line versions and a clear flowcell is also available. Maximum cable length is 25 feet (7.7 m) for this type of sensor. A preamplifier in a NEMA 4X enclosure is available for applications requiring longer distances between the sensor and monitor.


In this type of sensor, the silver/silver chloride reference element has been replaced by a pH sensitive glass electrode identical to the measuring electrode. This second glass electrode is housed in a chamber filled with pH 7 buffer which provides a stable reference. A high surface area reference junction electrically connects this reference system to the pH measuring element. The result is that pH is measured by the voltage difference between the two pH sensitive glass elements.
Differential pH sensors are the best choice for demanding applications such as wastewater, plating baths, aggressive industrial process water, or higher temperature applications. They are especially good in applications containing sulfur compounds that tend to poison the silver/silver chloride reference element found in conventional sensors. Because they are designed with replaceable reference junctions and have internal preamplifiers, these sensors tend to significantly outlast conventional sensors.


Sensor Options

Choice of either “differential” or “conventional” pH sensors. Differential sensors provide reliable, long lasting service in demanding applications while conventional sensors provide a lower cost alternative for clean water applications.


Automatic “Air Blast” sensor cleaning system available for reducing maintenance in applications where sensor fouling is a problem.


Automatic buffer recognition simplifies calibration.

AC Power Options

Power options include 115/230 VAC.

Analog Output Options

Two isolated 4-20 mA outputs are standard. Default setting provides analog outputs for pH/ORP and temperature.

PID Output

Standard PID control function assignable to one analog output.

Relay Contacts

Two SPDT relays are standard, with relay functions programmable for alarm, control, or trouble indication.

Flexible Mounting

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

Clear Display

Back-lit large LCD display provides clear visibility in any lighting conditions. A scrolling second line on the display provides additional information and programming prompts.